Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:
 "The main changes in the locking subsystem in this cycle were:

   - Add the Linux Kernel Memory Consistency Model (LKMM) subsystem,
     which is an an array of tools in tools/memory-model/ that formally
     describe the Linux memory coherency model (a.k.a.
     Documentation/memory-barriers.txt), and also produce 'litmus tests'
     in form of kernel code which can be directly executed and tested.

     Here's a high level background article about an earlier version of
     this work on LWN.net:

        https://lwn.net/Articles/718628/

     The design principles:

      "There is reason to believe that Documentation/memory-barriers.txt
       could use some help, and a major purpose of this patch is to
       provide that help in the form of a design-time tool that can
       produce all valid executions of a small fragment of concurrent
       Linux-kernel code, which is called a "litmus test". This tool's
       functionality is roughly similar to a full state-space search.
       Please note that this is a design-time tool, not useful for
       regression testing. However, we hope that the underlying
       Linux-kernel memory model will be incorporated into other tools
       capable of analyzing large bodies of code for regression-testing
       purposes."

     [...]

      "A second tool is klitmus7, which converts litmus tests to
       loadable kernel modules for direct testing. As with herd7, the
       klitmus7 code is freely available from

         http://diy.inria.fr/sources/index.html

       (and via "git" at https://github.com/herd/herdtools7)"

     [...]

     Credits go to:

      "This patch was the result of a most excellent collaboration
       founded by Jade Alglave and also including Alan Stern, Andrea
       Parri, and Luc Maranget."

     ... and to the gents listed in the MAINTAINERS entry:

        LINUX KERNEL MEMORY CONSISTENCY MODEL (LKMM)
        M:      Alan Stern <stern@rowland.harvard.edu>
        M:      Andrea Parri <parri.andrea@gmail.com>
        M:      Will Deacon <will.deacon@arm.com>
        M:      Peter Zijlstra <peterz@infradead.org>
        M:      Boqun Feng <boqun.feng@gmail.com>
        M:      Nicholas Piggin <npiggin@gmail.com>
        M:      David Howells <dhowells@redhat.com>
        M:      Jade Alglave <j.alglave@ucl.ac.uk>
        M:      Luc Maranget <luc.maranget@inria.fr>
        M:      "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>

     The LKMM project already found several bugs in Linux locking
     primitives and improved the understanding and the documentation of
     the Linux memory model all around.

   - Add KASAN instrumentation to atomic APIs (Dmitry Vyukov)

   - Add RWSEM API debugging and reorganize the lock debugging Kconfig
     (Waiman Long)

   - ... misc cleanups and other smaller changes"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (31 commits)
  locking/Kconfig: Restructure the lock debugging menu
  locking/Kconfig: Add LOCK_DEBUGGING_SUPPORT to make it more readable
  locking/rwsem: Add DEBUG_RWSEMS to look for lock/unlock mismatches
  lockdep: Make the lock debug output more useful
  locking/rtmutex: Handle non enqueued waiters gracefully in remove_waiter()
  locking/atomic, asm-generic, x86: Add comments for atomic instrumentation
  locking/atomic, asm-generic: Add KASAN instrumentation to atomic operations
  locking/atomic/x86: Switch atomic.h to use atomic-instrumented.h
  locking/atomic, asm-generic: Add asm-generic/atomic-instrumented.h
  locking/xchg/alpha: Remove superfluous memory barriers from the _local() variants
  tools/memory-model: Finish the removal of rb-dep, smp_read_barrier_depends(), and lockless_dereference()
  tools/memory-model: Add documentation of new litmus test
  tools/memory-model: Remove mention of docker/gentoo image
  locking/memory-barriers: De-emphasize smp_read_barrier_depends() some more
  locking/lockdep: Show unadorned pointers
  mutex: Drop linkage.h from mutex.h
  tools/memory-model: Remove rb-dep, smp_read_barrier_depends, and lockless_dereference
  tools/memory-model: Convert underscores to hyphens
  tools/memory-model: Add a S lock-based external-view litmus test
  tools/memory-model: Add required herd7 version to README file
  ...

Documentation/locking/lockdep-design.txt

@@ -27,7 +27,8 @@ lock-class.
 State
 -----
 
-The validator tracks lock-class usage history into 4n + 1 separate state bits:
+The validator tracks lock-class usage history into 4 * nSTATEs + 1 separate
+state bits:
 
 - 'ever held in STATE context'
 - 'ever held as readlock in STATE context'
@@ -37,7 +38,6 @@ The validator tracks lock-class usage history into 4n + 1 separate state bits:
 Where STATE can be either one of (kernel/locking/lockdep_states.h)
  - hardirq
  - softirq
- - reclaim_fs
 
 - 'ever used'                                       [ == !unused        ]
 
@@ -169,6 +169,53 @@ Note: When changing code to use the _nested() primitives, be careful and
 check really thoroughly that the hierarchy is correctly mapped; otherwise
 you can get false positives or false negatives.
 
+Annotations
+-----------
+
+Two constructs can be used to annotate and check where and if certain locks
+must be held: lockdep_assert_held*(&lock) and lockdep_*pin_lock(&lock).
+
+As the name suggests, lockdep_assert_held* family of macros assert that a
+particular lock is held at a certain time (and generate a WARN() otherwise).
+This annotation is largely used all over the kernel, e.g. kernel/sched/
+core.c
+
+  void update_rq_clock(struct rq *rq)
+  {
+	s64 delta;
+
+	lockdep_assert_held(&rq->lock);
+	[...]
+  }
+
+where holding rq->lock is required to safely update a rq's clock.
+
+The other family of macros is lockdep_*pin_lock(), which is admittedly only
+used for rq->lock ATM. Despite their limited adoption these annotations
+generate a WARN() if the lock of interest is "accidentally" unlocked. This turns
+out to be especially helpful to debug code with callbacks, where an upper
+layer assumes a lock remains taken, but a lower layer thinks it can maybe drop
+and reacquire the lock ("unwittingly" introducing races). lockdep_pin_lock()
+returns a 'struct pin_cookie' that is then used by lockdep_unpin_lock() to check
+that nobody tampered with the lock, e.g. kernel/sched/sched.h
+
+  static inline void rq_pin_lock(struct rq *rq, struct rq_flags *rf)
+  {
+	rf->cookie = lockdep_pin_lock(&rq->lock);
+	[...]
+  }
+
+  static inline void rq_unpin_lock(struct rq *rq, struct rq_flags *rf)
+  {
+	[...]
+	lockdep_unpin_lock(&rq->lock, rf->cookie);
+  }
+
+While comments about locking requirements might provide useful information,
+the runtime checks performed by annotations are invaluable when debugging
+locking problems and they carry the same level of details when inspecting
+code.  Always prefer annotations when in doubt!
+
 Proof of 100% correctness:
 --------------------------
 

Documentation/memory-barriers.txt

@@ -14,7 +14,11 @@ DISCLAIMER
 This document is not a specification; it is intentionally (for the sake of
 brevity) and unintentionally (due to being human) incomplete. This document is
 meant as a guide to using the various memory barriers provided by Linux, but
-in case of any doubt (and there are many) please ask.
+in case of any doubt (and there are many) please ask.  Some doubts may be
+resolved by referring to the formal memory consistency model and related
+documentation at tools/memory-model/.  Nevertheless, even this memory
+model should be viewed as the collective opinion of its maintainers rather
+than as an infallible oracle.
 
 To repeat, this document is not a specification of what Linux expects from
 hardware.
@@ -48,7 +52,7 @@ CONTENTS
 
      - Varieties of memory barrier.
      - What may not be assumed about memory barriers?
-     - Data dependency barriers.
+     - Data dependency barriers (historical).
      - Control dependencies.
      - SMP barrier pairing.
      - Examples of memory barrier sequences.
@@ -399,7 +403,7 @@ Memory barriers come in four basic varieties:
      where two loads are performed such that the second depends on the result
      of the first (eg: the first load retrieves the address to which the second
      load will be directed), a data dependency barrier would be required to
-     make sure that the target of the second load is updated before the address
+     make sure that the target of the second load is updated after the address
      obtained by the first load is accessed.
 
      A data dependency barrier is a partial ordering on interdependent loads
@@ -550,8 +554,15 @@ There are certain things that the Linux kernel memory barriers do not guarantee:
 	    Documentation/DMA-API.txt
 
 
-DATA DEPENDENCY BARRIERS
-------------------------
+DATA DEPENDENCY BARRIERS (HISTORICAL)
+-------------------------------------
+
+As of v4.15 of the Linux kernel, an smp_read_barrier_depends() was
+added to READ_ONCE(), which means that about the only people who
+need to pay attention to this section are those working on DEC Alpha
+architecture-specific code and those working on READ_ONCE() itself.
+For those who need it, and for those who are interested in the history,
+here is the story of data-dependency barriers.
 
 The usage requirements of data dependency barriers are a little subtle, and
 it's not always obvious that they're needed.  To illustrate, consider the
@@ -2839,8 +2850,9 @@ as that committed on CPU 1.
 
 
 To intervene, we need to interpolate a data dependency barrier or a read
-barrier between the loads.  This will force the cache to commit its coherency
-queue before processing any further requests:
+barrier between the loads (which as of v4.15 is supplied unconditionally
+by the READ_ONCE() macro).  This will force the cache to commit its
+coherency queue before processing any further requests:
 
 	CPU 1		CPU 2		COMMENT
 	===============	===============	=======================================
@@ -2869,8 +2881,8 @@ Other CPUs may also have split caches, but must coordinate between the various
 cachelets for normal memory accesses.  The semantics of the Alpha removes the
 need for hardware coordination in the absence of memory barriers, which
 permitted Alpha to sport higher CPU clock rates back in the day.  However,
-please note that smp_read_barrier_depends() should not be used except in
-Alpha arch-specific code and within the READ_ONCE() macro.
+please note that (again, as of v4.15) smp_read_barrier_depends() should not
+be used except in Alpha arch-specific code and within the READ_ONCE() macro.
 
 
 CACHE COHERENCY VS DMA
@@ -3035,7 +3047,9 @@ the data dependency barrier really becomes necessary as this synchronises both
 caches with the memory coherence system, thus making it seem like pointer
 changes vs new data occur in the right order.
 
-The Alpha defines the Linux kernel's memory barrier model.
+The Alpha defines the Linux kernel's memory model, although as of v4.15
+the Linux kernel's addition of smp_read_barrier_depends() to READ_ONCE()
+greatly reduced Alpha's impact on the memory model.
 
 See the subsection on "Cache Coherency" above.
 

MAINTAINERS

@@ -8162,6 +8162,24 @@ M:	Kees Cook <keescook@chromium.org>
 S:	Maintained
 F:	drivers/misc/lkdtm*
 
+LINUX KERNEL MEMORY CONSISTENCY MODEL (LKMM)
+M:	Alan Stern <stern@rowland.harvard.edu>
+M:	Andrea Parri <parri.andrea@gmail.com>
+M:	Will Deacon <will.deacon@arm.com>
+M:	Peter Zijlstra <peterz@infradead.org>
+M:	Boqun Feng <boqun.feng@gmail.com>
+M:	Nicholas Piggin <npiggin@gmail.com>
+M:	David Howells <dhowells@redhat.com>
+M:	Jade Alglave <j.alglave@ucl.ac.uk>
+M:	Luc Maranget <luc.maranget@inria.fr>
+M:	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
+R:	Akira Yokosawa <akiyks@gmail.com>
+L:	linux-kernel@vger.kernel.org
+S:	Supported
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
+F:	tools/memory-model/
+F:	Documentation/memory-barriers.txt
+
 LINUX SECURITY MODULE (LSM) FRAMEWORK
 M:	Chris Wright <chrisw@sous-sol.org>
 L:	linux-security-module@vger.kernel.org

arch/alpha/include/asm/cmpxchg.h

@@ -38,19 +38,31 @@
 #define ____cmpxchg(type, args...)	__cmpxchg ##type(args)
 #include <asm/xchg.h>
 
+/*
+ * The leading and the trailing memory barriers guarantee that these
+ * operations are fully ordered.
+ */
 #define xchg(ptr, x)							\
 ({									\
+	__typeof__(*(ptr)) __ret;					\
 	__typeof__(*(ptr)) _x_ = (x);					\
-	(__typeof__(*(ptr))) __xchg((ptr), (unsigned long)_x_,		\
-				 sizeof(*(ptr)));			\
+	smp_mb();							\
+	__ret = (__typeof__(*(ptr)))					\
+		__xchg((ptr), (unsigned long)_x_, sizeof(*(ptr)));	\
+	smp_mb();							\
+	__ret;								\
 })
 
 #define cmpxchg(ptr, o, n)						\
 ({									\
+	__typeof__(*(ptr)) __ret;					\
 	__typeof__(*(ptr)) _o_ = (o);					\
 	__typeof__(*(ptr)) _n_ = (n);					\
-	(__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_,	\
-				    (unsigned long)_n_,	sizeof(*(ptr)));\
+	smp_mb();							\
+	__ret = (__typeof__(*(ptr))) __cmpxchg((ptr),			\
+		(unsigned long)_o_, (unsigned long)_n_, sizeof(*(ptr)));\
+	smp_mb();							\
+	__ret;								\
 })
 
 #define cmpxchg64(ptr, o, n)						\

arch/alpha/include/asm/xchg.h

@@ -12,10 +12,6 @@
  * Atomic exchange.
  * Since it can be used to implement critical sections
  * it must clobber "memory" (also for interrupts in UP).
- *
- * The leading and the trailing memory barriers guarantee that these
- * operations are fully ordered.
- *
  */
 
 static inline unsigned long
@@ -23,7 +19,6 @@ ____xchg(_u8, volatile char *m, unsigned long val)
 {
 	unsigned long ret, tmp, addr64;
 
-	smp_mb();
 	__asm__ __volatile__(
 	"	andnot	%4,7,%3\n"
 	"	insbl	%1,%4,%1\n"
@@ -38,7 +33,6 @@ ____xchg(_u8, volatile char *m, unsigned long val)
 	".previous"
 	: "=&r" (ret), "=&r" (val), "=&r" (tmp), "=&r" (addr64)
 	: "r" ((long)m), "1" (val) : "memory");
-	smp_mb();
 
 	return ret;
 }
@@ -48,7 +42,6 @@ ____xchg(_u16, volatile short *m, unsigned long val)
 {
 	unsigned long ret, tmp, addr64;
 
-	smp_mb();
 	__asm__ __volatile__(
 	"	andnot	%4,7,%3\n"
 	"	inswl	%1,%4,%1\n"
@@ -63,7 +56,6 @@ ____xchg(_u16, volatile short *m, unsigned long val)
 	".previous"
 	: "=&r" (ret), "=&r" (val), "=&r" (tmp), "=&r" (addr64)
 	: "r" ((long)m), "1" (val) : "memory");
-	smp_mb();
 
 	return ret;
 }
@@ -73,7 +65,6 @@ ____xchg(_u32, volatile int *m, unsigned long val)
 {
 	unsigned long dummy;
 
-	smp_mb();
 	__asm__ __volatile__(
 	"1:	ldl_l %0,%4\n"
 	"	bis $31,%3,%1\n"
@@ -84,7 +75,6 @@ ____xchg(_u32, volatile int *m, unsigned long val)
 	".previous"
 	: "=&r" (val), "=&r" (dummy), "=m" (*m)
 	: "rI" (val), "m" (*m) : "memory");
-	smp_mb();
 
 	return val;
 }
@@ -94,7 +84,6 @@ ____xchg(_u64, volatile long *m, unsigned long val)
 {
 	unsigned long dummy;
 
-	smp_mb();
 	__asm__ __volatile__(
 	"1:	ldq_l %0,%4\n"
 	"	bis $31,%3,%1\n"
@@ -105,7 +94,6 @@ ____xchg(_u64, volatile long *m, unsigned long val)
 	".previous"
 	: "=&r" (val), "=&r" (dummy), "=m" (*m)
 	: "rI" (val), "m" (*m) : "memory");
-	smp_mb();
 
 	return val;
 }
@@ -135,13 +123,6 @@ ____xchg(, volatile void *ptr, unsigned long x, int size)
  * Atomic compare and exchange.  Compare OLD with MEM, if identical,
  * store NEW in MEM.  Return the initial value in MEM.  Success is
  * indicated by comparing RETURN with OLD.
- *
- * The leading and the trailing memory barriers guarantee that these
- * operations are fully ordered.
- *
- * The trailing memory barrier is placed in SMP unconditionally, in
- * order to guarantee that dependency ordering is preserved when a
- * dependency is headed by an unsuccessful operation.
  */
 
 static inline unsigned long
@@ -149,7 +130,6 @@ ____cmpxchg(_u8, volatile char *m, unsigned char old, unsigned char new)
 {
 	unsigned long prev, tmp, cmp, addr64;
 
-	smp_mb();
 	__asm__ __volatile__(
 	"	andnot	%5,7,%4\n"
 	"	insbl	%1,%5,%1\n"
@@ -167,7 +147,6 @@ ____cmpxchg(_u8, volatile char *m, unsigned char old, unsigned char new)
 	".previous"
 	: "=&r" (prev), "=&r" (new), "=&r" (tmp), "=&r" (cmp), "=&r" (addr64)
 	: "r" ((long)m), "Ir" (old), "1" (new) : "memory");
-	smp_mb();
 
 	return prev;
 }
@@ -177,7 +156,6 @@ ____cmpxchg(_u16, volatile short *m, unsigned short old, unsigned short new)
 {
 	unsigned long prev, tmp, cmp, addr64;
 
-	smp_mb();
 	__asm__ __volatile__(
 	"	andnot	%5,7,%4\n"
 	"	inswl	%1,%5,%1\n"
@@ -195,7 +173,6 @@ ____cmpxchg(_u16, volatile short *m, unsigned short old, unsigned short new)
 	".previous"
 	: "=&r" (prev), "=&r" (new), "=&r" (tmp), "=&r" (cmp), "=&r" (addr64)
 	: "r" ((long)m), "Ir" (old), "1" (new) : "memory");
-	smp_mb();
 
 	return prev;
 }
@@ -205,7 +182,6 @@ ____cmpxchg(_u32, volatile int *m, int old, int new)
 {
 	unsigned long prev, cmp;
 
-	smp_mb();
 	__asm__ __volatile__(
 	"1:	ldl_l %0,%5\n"
 	"	cmpeq %0,%3,%1\n"
@@ -219,7 +195,6 @@ ____cmpxchg(_u32, volatile int *m, int old, int new)
 	".previous"
 	: "=&r"(prev), "=&r"(cmp), "=m"(*m)
 	: "r"((long) old), "r"(new), "m"(*m) : "memory");
-	smp_mb();
 
 	return prev;
 }
@@ -229,7 +204,6 @@ ____cmpxchg(_u64, volatile long *m, unsigned long old, unsigned long new)
 {
 	unsigned long prev, cmp;
 
-	smp_mb();
 	__asm__ __volatile__(
 	"1:	ldq_l %0,%5\n"
 	"	cmpeq %0,%3,%1\n"
@@ -243,7 +217,6 @@ ____cmpxchg(_u64, volatile long *m, unsigned long old, unsigned long new)
 	".previous"
 	: "=&r"(prev), "=&r"(cmp), "=m"(*m)
 	: "r"((long) old), "r"(new), "m"(*m) : "memory");
-	smp_mb();
 
 	return prev;
 }

arch/x86/include/asm/atomic.h

@@ -17,36 +17,40 @@
 #define ATOMIC_INIT(i)	{ (i) }
 
 /**
- * atomic_read - read atomic variable
+ * arch_atomic_read - read atomic variable
  * @v: pointer of type atomic_t
  *
  * Atomically reads the value of @v.
  */
-static __always_inline int atomic_read(const atomic_t *v)
+static __always_inline int arch_atomic_read(const atomic_t *v)
 {
+	/*
+	 * Note for KASAN: we deliberately don't use READ_ONCE_NOCHECK() here,
+	 * it's non-inlined function that increases binary size and stack usage.
+	 */
 	return READ_ONCE((v)->counter);
 }
 
 /**
- * atomic_set - set atomic variable
+ * arch_atomic_set - set atomic variable
  * @v: pointer of type atomic_t
  * @i: required value
  *
  * Atomically sets the value of @v to @i.
  */
-static __always_inline void atomic_set(atomic_t *v, int i)
+static __always_inline void arch_atomic_set(atomic_t *v, int i)
 {
 	WRITE_ONCE(v->counter, i);
 }
 
 /**
- * atomic_add - add integer to atomic variable
+ * arch_atomic_add - add integer to atomic variable
  * @i: integer value to add
  * @v: pointer of type atomic_t
  *
  * Atomically adds @i to @v.
  */
-static __always_inline void atomic_add(int i, atomic_t *v)
+static __always_inline void arch_atomic_add(int i, atomic_t *v)
 {
 	asm volatile(LOCK_PREFIX "addl %1,%0"
 		     : "+m" (v->counter)
@@ -54,13 +58,13 @@ static __always_inline void atomic_add(int i, atomic_t *v)
 }
 
 /**
- * atomic_sub - subtract integer from atomic variable
+ * arch_atomic_sub - subtract integer from atomic variable
  * @i: integer value to subtract
  * @v: pointer of type atomic_t
  *
  * Atomically subtracts @i from @v.
  */
-static __always_inline void atomic_sub(int i, atomic_t *v)
+static __always_inline void arch_atomic_sub(int i, atomic_t *v)
 {
 	asm volatile(LOCK_PREFIX "subl %1,%0"
 		     : "+m" (v->counter)
@@ -68,7 +72,7 @@ static __always_inline void atomic_sub(int i, atomic_t *v)
 }
 
 /**
- * atomic_sub_and_test - subtract value from variable and test result
+ * arch_atomic_sub_and_test - subtract value from variable and test result
  * @i: integer value to subtract
  * @v: pointer of type atomic_t
  *
@@ -76,63 +80,63 @@ static __always_inline void atomic_sub(int i, atomic_t *v)
  * true if the result is zero, or false for all
  * other cases.
  */
-static __always_inline bool atomic_sub_and_test(int i, atomic_t *v)
+static __always_inline bool arch_atomic_sub_and_test(int i, atomic_t *v)
 {
 	GEN_BINARY_RMWcc(LOCK_PREFIX "subl", v->counter, "er", i, "%0", e);
 }
 
 /**
- * atomic_inc - increment atomic variable
+ * arch_atomic_inc - increment atomic variable
  * @v: pointer of type atomic_t
  *
  * Atomically increments @v by 1.
  */
-static __always_inline void atomic_inc(atomic_t *v)
+static __always_inline void arch_atomic_inc(atomic_t *v)
 {
 	asm volatile(LOCK_PREFIX "incl %0"
 		     : "+m" (v->counter));
 }
 
 /**
- * atomic_dec - decrement atomic variable
+ * arch_atomic_dec - decrement atomic variable
  * @v: pointer of type atomic_t
  *
  * Atomically decrements @v by 1.
  */
-static __always_inline void atomic_dec(atomic_t *v)
+static __always_inline void arch_atomic_dec(atomic_t *v)
 {
 	asm volatile(LOCK_PREFIX "decl %0"
 		     : "+m" (v->counter));
 }
 
 /**
- * atomic_dec_and_test - decrement and test
+ * arch_atomic_dec_and_test - decrement and test
  * @v: pointer of type atomic_t
  *
  * Atomically decrements @v by 1 and
  * returns true if the result is 0, or false for all other
  * cases.
  */
-static __always_inline bool atomic_dec_and_test(atomic_t *v)
+static __always_inline bool arch_atomic_dec_and_test(atomic_t *v)
 {
 	GEN_UNARY_RMWcc(LOCK_PREFIX "decl", v->counter, "%0", e);
 }
 
 /**
- * atomic_inc_and_test - increment and test
+ * arch_atomic_inc_and_test - increment and test
  * @v: pointer of type atomic_t
  *
  * Atomically increments @v by 1
  * and returns true if the result is zero, or false for all
  * other cases.
  */
-static __always_inline bool atomic_inc_and_test(atomic_t *v)
+static __always_inline bool arch_atomic_inc_and_test(atomic_t *v)
 {
 	GEN_UNARY_RMWcc(LOCK_PREFIX "incl", v->counter, "%0", e);
 }
 
 /**
- * atomic_add_negative - add and test if negative
+ * arch_atomic_add_negative - add and test if negative
  * @i: integer value to add
  * @v: pointer of type atomic_t
  *
@@ -140,65 +144,65 @@ static __always_inline bool atomic_inc_and_test(atomic_t *v)
  * if the result is negative, or false when
  * result is greater than or equal to zero.
  */
-static __always_inline bool atomic_add_negative(int i, atomic_t *v)
+static __always_inline bool arch_atomic_add_negative(int i, atomic_t *v)
 {
 	GEN_BINARY_RMWcc(LOCK_PREFIX "addl", v->counter, "er", i, "%0", s);
 }
 
 /**
- * atomic_add_return - add integer and return
+ * arch_atomic_add_return - add integer and return
  * @i: integer value to add
  * @v: pointer of type atomic_t
  *
  * Atomically adds @i to @v and returns @i + @v
  */
-static __always_inline int atomic_add_return(int i, atomic_t *v)
+static __always_inline int arch_atomic_add_return(int i, atomic_t *v)
 {
 	return i + xadd(&v->counter, i);
 }
 
 /**
- * atomic_sub_return - subtract integer and return
+ * arch_atomic_sub_return - subtract integer and return
  * @v: pointer of type atomic_t
  * @i: integer value to subtract
  *
  * Atomically subtracts @i from @v and returns @v - @i
  */
-static __always_inline int atomic_sub_return(int i, atomic_t *v)
+static __always_inline int arch_atomic_sub_return(int i, atomic_t *v)
 {
-	return atomic_add_return(-i, v);
+	return arch_atomic_add_return(-i, v);
 }
 
-#define atomic_inc_return(v)  (atomic_add_return(1, v))
-#define atomic_dec_return(v)  (atomic_sub_return(1, v))
+#define arch_atomic_inc_return(v)  (arch_atomic_add_return(1, v))
+#define arch_atomic_dec_return(v)  (arch_atomic_sub_return(1, v))
 
-static __always_inline int atomic_fetch_add(int i, atomic_t *v)
+static __always_inline int arch_atomic_fetch_add(int i, atomic_t *v)
 {
 	return xadd(&v->counter, i);
 }
 
-static __always_inline int atomic_fetch_sub(int i, atomic_t *v)
+static __always_inline int arch_atomic_fetch_sub(int i, atomic_t *v)
 {
 	return xadd(&v->counter, -i);
 }
 
-static __always_inline int atomic_cmpxchg(atomic_t *v, int old, int new)
+static __always_inline int arch_atomic_cmpxchg(atomic_t *v, int old, int new)
 {
-	return cmpxchg(&v->counter, old, new);
+	return arch_cmpxchg(&v->counter, old, new);
 }
 
-#define atomic_try_cmpxchg atomic_try_cmpxchg
-static __always_inline bool atomic_try_cmpxchg(atomic_t *v, int *old, int new)
+#define arch_atomic_try_cmpxchg arch_atomic_try_cmpxchg
+static __always_inline bool arch_atomic_try_cmpxchg(atomic_t *v, int *old, int new)
 {
 	return try_cmpxchg(&v->counter, old, new);
 }
 
-static inline int atomic_xchg(atomic_t *v, int new)
+static inline int arch_atomic_xchg(atomic_t *v, int new)
 {
 	return xchg(&v->counter, new);
 }
 
-static inline void atomic_and(int i, atomic_t *v)
+static inline void arch_atomic_and(int i, atomic_t *v)
 {
 	asm volatile(LOCK_PREFIX "andl %1,%0"
 			: "+m" (v->counter)
@@ -206,16 +210,16 @@ static inline void atomic_and(int i, atomic_t *v)
 			: "memory");
 }
 
-static inline int atomic_fetch_and(int i, atomic_t *v)
+static inline int arch_atomic_fetch_and(int i, atomic_t *v)
 {
-	int val = atomic_read(v);
+	int val = arch_atomic_read(v);
 
-	do { } while (!atomic_try_cmpxchg(v, &val, val & i));
+	do { } while (!arch_atomic_try_cmpxchg(v, &val, val & i));
 
 	return val;
 }
 
-static inline void atomic_or(int i, atomic_t *v)
+static inline void arch_atomic_or(int i, atomic_t *v)
 {
 	asm volatile(LOCK_PREFIX "orl %1,%0"
 			: "+m" (v->counter)
@@ -223,16 +227,16 @@ static inline void atomic_or(int i, atomic_t *v)
 			: "memory");
 }
 
-static inline int atomic_fetch_or(int i, atomic_t *v)
+static inline int arch_atomic_fetch_or(int i, atomic_t *v)
 {
-	int val = atomic_read(v);
+	int val = arch_atomic_read(v);
 
-	do { } while (!atomic_try_cmpxchg(v, &val, val | i));
+	do { } while (!arch_atomic_try_cmpxchg(v, &val, val | i));
 
 	return val;
 }
 
-static inline void atomic_xor(int i, atomic_t *v)
+static inline void arch_atomic_xor(int i, atomic_t *v)
 {
 	asm volatile(LOCK_PREFIX "xorl %1,%0"
 			: "+m" (v->counter)
@@ -240,17 +244,17 @@ static inline void atomic_xor(int i, atomic_t *v)
 			: "memory");
 }
 
-static inline int atomic_fetch_xor(int i, atomic_t *v)
+static inline int arch_atomic_fetch_xor(int i, atomic_t *v)
 {
-	int val = atomic_read(v);
+	int val = arch_atomic_read(v);
 
-	do { } while (!atomic_try_cmpxchg(v, &val, val ^ i));
+	do { } while (!arch_atomic_try_cmpxchg(v, &val, val ^ i));
 
 	return val;
 }
 
 /**
- * __atomic_add_unless - add unless the number is already a given value
+ * __arch_atomic_add_unless - add unless the number is already a given value
  * @v: pointer of type atomic_t
  * @a: the amount to add to v...
  * @u: ...unless v is equal to u.
@@ -258,14 +262,14 @@ static inline int atomic_fetch_xor(int i, atomic_t *v)
  * Atomically adds @a to @v, so long as @v was not already @u.
  * Returns the old value of @v.
  */
-static __always_inline int __atomic_add_unless(atomic_t *v, int a, int u)
+static __always_inline int __arch_atomic_add_unless(atomic_t *v, int a, int u)
 {
-	int c = atomic_read(v);
+	int c = arch_atomic_read(v);
 
 	do {
 		if (unlikely(c == u))
 			break;
-	} while (!atomic_try_cmpxchg(v, &c, c + a));
+	} while (!arch_atomic_try_cmpxchg(v, &c, c + a));
 
 	return c;
 }
@@ -276,4 +280,6 @@ static __always_inline int __atomic_add_unless(atomic_t *v, int a, int u)
 # include <asm/atomic64_64.h>
 #endif
 
+#include <asm-generic/atomic-instrumented.h>
+
 #endif /* _ASM_X86_ATOMIC_H */

arch/x86/include/asm/atomic64_64.h

@@ -11,37 +11,37 @@
 #define ATOMIC64_INIT(i)	{ (i) }
 
 /**
- * atomic64_read - read atomic64 variable
+ * arch_atomic64_read - read atomic64 variable
  * @v: pointer of type atomic64_t
  *
  * Atomically reads the value of @v.
  * Doesn't imply a read memory barrier.
  */
-static inline long atomic64_read(const atomic64_t *v)
+static inline long arch_atomic64_read(const atomic64_t *v)
 {
 	return READ_ONCE((v)->counter);
 }
 
 /**
- * atomic64_set - set atomic64 variable
+ * arch_atomic64_set - set atomic64 variable
  * @v: pointer to type atomic64_t
  * @i: required value
  *
  * Atomically sets the value of @v to @i.
  */
-static inline void atomic64_set(atomic64_t *v, long i)
+static inline void arch_atomic64_set(atomic64_t *v, long i)
 {
 	WRITE_ONCE(v->counter, i);
 }
 
 /**
- * atomic64_add - add integer to atomic64 variable
+ * arch_atomic64_add - add integer to atomic64 variable
  * @i: integer value to add
  * @v: pointer to type atomic64_t
  *
  * Atomically adds @i to @v.
  */
-static __always_inline void atomic64_add(long i, atomic64_t *v)
+static __always_inline void arch_atomic64_add(long i, atomic64_t *v)
 {
 	asm volatile(LOCK_PREFIX "addq %1,%0"
 		     : "=m" (v->counter)
@@ -49,13 +49,13 @@ static __always_inline void atomic64_add(long i, atomic64_t *v)
 }
 
 /**
- * atomic64_sub - subtract the atomic64 variable
+ * arch_atomic64_sub - subtract the atomic64 variable
  * @i: integer value to subtract
  * @v: pointer to type atomic64_t
  *
  * Atomically subtracts @i from @v.
  */
-static inline void atomic64_sub(long i, atomic64_t *v)
+static inline void arch_atomic64_sub(long i, atomic64_t *v)
 {
 	asm volatile(LOCK_PREFIX "subq %1,%0"
 		     : "=m" (v->counter)
@@ -63,7 +63,7 @@ static inline void atomic64_sub(long i, atomic64_t *v)
 }
 
 /**
- * atomic64_sub_and_test - subtract value from variable and test result
+ * arch_atomic64_sub_and_test - subtract value from variable and test result
  * @i: integer value to subtract
  * @v: pointer to type atomic64_t
  *
@@ -71,18 +71,18 @@ static inline void atomic64_sub(long i, atomic64_t *v)
  * true if the result is zero, or false for all
  * other cases.
  */
-static inline bool atomic64_sub_and_test(long i, atomic64_t *v)
+static inline bool arch_atomic64_sub_and_test(long i, atomic64_t *v)
 {
 	GEN_BINARY_RMWcc(LOCK_PREFIX "subq", v->counter, "er", i, "%0", e);
 }
 
 /**
- * atomic64_inc - increment atomic64 variable
+ * arch_atomic64_inc - increment atomic64 variable
  * @v: pointer to type atomic64_t
  *
  * Atomically increments @v by 1.
  */
-static __always_inline void atomic64_inc(atomic64_t *v)
+static __always_inline void arch_atomic64_inc(atomic64_t *v)
 {
 	asm volatile(LOCK_PREFIX "incq %0"
 		     : "=m" (v->counter)
@@ -90,12 +90,12 @@ static __always_inline void atomic64_inc(atomic64_t *v)
 }
 
 /**
- * atomic64_dec - decrement atomic64 variable
+ * arch_atomic64_dec - decrement atomic64 variable
  * @v: pointer to type atomic64_t
  *
  * Atomically decrements @v by 1.
  */
-static __always_inline void atomic64_dec(atomic64_t *v)
+static __always_inline void arch_atomic64_dec(atomic64_t *v)
 {
 	asm volatile(LOCK_PREFIX "decq %0"
 		     : "=m" (v->counter)
@@ -103,33 +103,33 @@ static __always_inline void atomic64_dec(atomic64_t *v)
 }
 
 /**
- * atomic64_dec_and_test - decrement and test
+ * arch_atomic64_dec_and_test - decrement and test
  * @v: pointer to type atomic64_t
  *
  * Atomically decrements @v by 1 and
  * returns true if the result is 0, or false for all other
  * cases.
  */
-static inline bool atomic64_dec_and_test(atomic64_t *v)
+static inline bool arch_atomic64_dec_and_test(atomic64_t *v)
 {
 	GEN_UNARY_RMWcc(LOCK_PREFIX "decq", v->counter, "%0", e);
 }
 
 /**
- * atomic64_inc_and_test - increment and test
+ * arch_atomic64_inc_and_test - increment and test
  * @v: pointer to type atomic64_t
  *
  * Atomically increments @v by 1
  * and returns true if the result is zero, or false for all
  * other cases.
  */
-static inline bool atomic64_inc_and_test(atomic64_t *v)
+static inline bool arch_atomic64_inc_and_test(atomic64_t *v)
 {
 	GEN_UNARY_RMWcc(LOCK_PREFIX "incq", v->counter, "%0", e);
 }
 
 /**
- * atomic64_add_negative - add and test if negative
+ * arch_atomic64_add_negative - add and test if negative
  * @i: integer value to add
  * @v: pointer to type atomic64_t
  *
@@ -137,59 +137,59 @@ static inline bool atomic64_inc_and_test(atomic64_t *v)
  * if the result is negative, or false when
  * result is greater than or equal to zero.
  */
-static inline bool atomic64_add_negative(long i, atomic64_t *v)
+static inline bool arch_atomic64_add_negative(long i, atomic64_t *v)
 {
 	GEN_BINARY_RMWcc(LOCK_PREFIX "addq", v->counter, "er", i, "%0", s);
 }
 
 /**
- * atomic64_add_return - add and return
+ * arch_atomic64_add_return - add and return
  * @i: integer value to add
  * @v: pointer to type atomic64_t
  *
  * Atomically adds @i to @v and returns @i + @v
  */
-static __always_inline long atomic64_add_return(long i, atomic64_t *v)
+static __always_inline long arch_atomic64_add_return(long i, atomic64_t *v)
 {
 	return i + xadd(&v->counter, i);
 }
 
-static inline long atomic64_sub_return(long i, atomic64_t *v)
+static inline long arch_atomic64_sub_return(long i, atomic64_t *v)
 {
-	return atomic64_add_return(-i, v);
+	return arch_atomic64_add_return(-i, v);
 }
 
-static inline long atomic64_fetch_add(long i, atomic64_t *v)
+static inline long arch_atomic64_fetch_add(long i, atomic64_t *v)
 {
 	return xadd(&v->counter, i);
 }
 
-static inline long atomic64_fetch_sub(long i, atomic64_t *v)
+static inline long arch_atomic64_fetch_sub(long i, atomic64_t *v)
 {
 	return xadd(&v->counter, -i);
 }
 
-#define atomic64_inc_return(v)  (atomic64_add_return(1, (v)))
-#define atomic64_dec_return(v)  (atomic64_sub_return(1, (v)))
+#define arch_atomic64_inc_return(v)  (arch_atomic64_add_return(1, (v)))
+#define arch_atomic64_dec_return(v)  (arch_atomic64_sub_return(1, (v)))
 
-static inline long atomic64_cmpxchg(atomic64_t *v, long old, long new)
+static inline long arch_atomic64_cmpxchg(atomic64_t *v, long old, long new)
 {
-	return cmpxchg(&v->counter, old, new);
+	return arch_cmpxchg(&v->counter, old, new);
 }
 
-#define atomic64_try_cmpxchg atomic64_try_cmpxchg
-static __always_inline bool atomic64_try_cmpxchg(atomic64_t *v, s64 *old, long new)
+#define arch_atomic64_try_cmpxchg arch_atomic64_try_cmpxchg
+static __always_inline bool arch_atomic64_try_cmpxchg(atomic64_t *v, s64 *old, long new)
 {
 	return try_cmpxchg(&v->counter, old, new);
 }
 
-static inline long atomic64_xchg(atomic64_t *v, long new)
+static inline long arch_atomic64_xchg(atomic64_t *v, long new)
 {
 	return xchg(&v->counter, new);
 }
 
 /**
- * atomic64_add_unless - add unless the number is a given value
+ * arch_atomic64_add_unless - add unless the number is a given value
  * @v: pointer of type atomic64_t
  * @a: the amount to add to v...
  * @u: ...unless v is equal to u.
@@ -197,37 +197,37 @@ static inline long atomic64_xchg(atomic64_t *v, long new)
  * Atomically adds @a to @v, so long as it was not @u.
  * Returns the old value of @v.
  */
-static inline bool atomic64_add_unless(atomic64_t *v, long a, long u)
+static inline bool arch_atomic64_add_unless(atomic64_t *v, long a, long u)
 {
-	s64 c = atomic64_read(v);
+	s64 c = arch_atomic64_read(v);
 	do {
 		if (unlikely(c == u))
 			return false;
-	} while (!atomic64_try_cmpxchg(v, &c, c + a));
+	} while (!arch_atomic64_try_cmpxchg(v, &c, c + a));
 	return true;
 }
 
-#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)
+#define arch_atomic64_inc_not_zero(v) arch_atomic64_add_unless((v), 1, 0)
 
 /*
- * atomic64_dec_if_positive - decrement by 1 if old value positive
+ * arch_atomic64_dec_if_positive - decrement by 1 if old value positive
  * @v: pointer of type atomic_t
  *
  * The function returns the old value of *v minus 1, even if
  * the atomic variable, v, was not decremented.
  */
-static inline long atomic64_dec_if_positive(atomic64_t *v)
+static inline long arch_atomic64_dec_if_positive(atomic64_t *v)
 {
-	s64 dec, c = atomic64_read(v);
+	s64 dec, c = arch_atomic64_read(v);
 	do {
 		dec = c - 1;
 		if (unlikely(dec < 0))
 			break;
-	} while (!atomic64_try_cmpxchg(v, &c, dec));
+	} while (!arch_atomic64_try_cmpxchg(v, &c, dec));
 	return dec;
 }
 
-static inline void atomic64_and(long i, atomic64_t *v)
+static inline void arch_atomic64_and(long i, atomic64_t *v)
 {
 	asm volatile(LOCK_PREFIX "andq %1,%0"
 			: "+m" (v->counter)
@@ -235,16 +235,16 @@ static inline void atomic64_and(long i, atomic64_t *v)
 			: "memory");
 }
 
-static inline long atomic64_fetch_and(long i, atomic64_t *v)
+static inline long arch_atomic64_fetch_and(long i, atomic64_t *v)
 {
-	s64 val = atomic64_read(v);
+	s64 val = arch_atomic64_read(v);
 
 	do {
-	} while (!atomic64_try_cmpxchg(v, &val, val & i));
+	} while (!arch_atomic64_try_cmpxchg(v, &val, val & i));
 	return val;
 }
 
-static inline void atomic64_or(long i, atomic64_t *v)
+static inline void arch_atomic64_or(long i, atomic64_t *v)
 {
 	asm volatile(LOCK_PREFIX "orq %1,%0"
 			: "+m" (v->counter)
@@ -252,16 +252,16 @@ static inline void atomic64_or(long i, atomic64_t *v)
 			: "memory");
 }
 
-static inline long atomic64_fetch_or(long i, atomic64_t *v)
+static inline long arch_atomic64_fetch_or(long i, atomic64_t *v)
 {
-	s64 val = atomic64_read(v);
+	s64 val = arch_atomic64_read(v);
 
 	do {
-	} while (!atomic64_try_cmpxchg(v, &val, val | i));
+	} while (!arch_atomic64_try_cmpxchg(v, &val, val | i));
 	return val;
 }
 
-static inline void atomic64_xor(long i, atomic64_t *v)
+static inline void arch_atomic64_xor(long i, atomic64_t *v)
 {
 	asm volatile(LOCK_PREFIX "xorq %1,%0"
 			: "+m" (v->counter)
@@ -269,12 +269,12 @@ static inline void atomic64_xor(long i, atomic64_t *v)
 			: "memory");
 }
 
-static inline long atomic64_fetch_xor(long i, atomic64_t *v)
+static inline long arch_atomic64_fetch_xor(long i, atomic64_t *v)
 {
-	s64 val = atomic64_read(v);
+	s64 val = arch_atomic64_read(v);
 
 	do {
-	} while (!atomic64_try_cmpxchg(v, &val, val ^ i));
+	} while (!arch_atomic64_try_cmpxchg(v, &val, val ^ i));
 	return val;
 }
 

arch/x86/include/asm/cmpxchg.h

@@ -145,13 +145,13 @@ extern void __add_wrong_size(void)
 # include <asm/cmpxchg_64.h>
 #endif
 
-#define cmpxchg(ptr, old, new)						\
+#define arch_cmpxchg(ptr, old, new)					\
 	__cmpxchg(ptr, old, new, sizeof(*(ptr)))
 
-#define sync_cmpxchg(ptr, old, new)					\
+#define arch_sync_cmpxchg(ptr, old, new)				\
 	__sync_cmpxchg(ptr, old, new, sizeof(*(ptr)))
 
-#define cmpxchg_local(ptr, old, new)					\
+#define arch_cmpxchg_local(ptr, old, new)				\
 	__cmpxchg_local(ptr, old, new, sizeof(*(ptr)))
 
 
@@ -250,10 +250,10 @@ extern void __add_wrong_size(void)
 	__ret;								\
 })
 
-#define cmpxchg_double(p1, p2, o1, o2, n1, n2) \
+#define arch_cmpxchg_double(p1, p2, o1, o2, n1, n2) \
 	__cmpxchg_double(LOCK_PREFIX, p1, p2, o1, o2, n1, n2)
 
-#define cmpxchg_double_local(p1, p2, o1, o2, n1, n2) \
+#define arch_cmpxchg_double_local(p1, p2, o1, o2, n1, n2) \
 	__cmpxchg_double(, p1, p2, o1, o2, n1, n2)
 
 #endif	/* ASM_X86_CMPXCHG_H */

arch/x86/include/asm/cmpxchg_32.h

@@ -36,10 +36,10 @@ static inline void set_64bit(volatile u64 *ptr, u64 value)
 }
 
 #ifdef CONFIG_X86_CMPXCHG64
-#define cmpxchg64(ptr, o, n)						\
+#define arch_cmpxchg64(ptr, o, n)					\
 	((__typeof__(*(ptr)))__cmpxchg64((ptr), (unsigned long long)(o), \
 					 (unsigned long long)(n)))
-#define cmpxchg64_local(ptr, o, n)					\
+#define arch_cmpxchg64_local(ptr, o, n)					\
 	((__typeof__(*(ptr)))__cmpxchg64_local((ptr), (unsigned long long)(o), \
 					       (unsigned long long)(n)))
 #endif
@@ -76,7 +76,7 @@ static inline u64 __cmpxchg64_local(volatile u64 *ptr, u64 old, u64 new)
  * to simulate the cmpxchg8b on the 80386 and 80486 CPU.
  */
 
-#define cmpxchg64(ptr, o, n)					\
+#define arch_cmpxchg64(ptr, o, n)				\
 ({								\
 	__typeof__(*(ptr)) __ret;				\
 	__typeof__(*(ptr)) __old = (o);				\
@@ -93,7 +93,7 @@ static inline u64 __cmpxchg64_local(volatile u64 *ptr, u64 old, u64 new)
 	__ret; })
 
 
-#define cmpxchg64_local(ptr, o, n)				\
+#define arch_cmpxchg64_local(ptr, o, n)				\
 ({								\
 	__typeof__(*(ptr)) __ret;				\
 	__typeof__(*(ptr)) __old = (o);				\

arch/x86/include/asm/cmpxchg_64.h

@@ -7,13 +7,13 @@ static inline void set_64bit(volatile u64 *ptr, u64 val)
 	*ptr = val;
 }
 
-#define cmpxchg64(ptr, o, n)						\
+#define arch_cmpxchg64(ptr, o, n)					\
 ({									\
 	BUILD_BUG_ON(sizeof(*(ptr)) != 8);				\
 	cmpxchg((ptr), (o), (n));					\
 })
 
-#define cmpxchg64_local(ptr, o, n)					\
+#define arch_cmpxchg64_local(ptr, o, n)					\
 ({									\
 	BUILD_BUG_ON(sizeof(*(ptr)) != 8);				\
 	cmpxchg_local((ptr), (o), (n));					\

include/linux/mutex.h

@@ -14,7 +14,6 @@
 #include <asm/current.h>
 #include <linux/list.h>
 #include <linux/spinlock_types.h>
-#include <linux/linkage.h>
 #include <linux/lockdep.h>
 #include <linux/atomic.h>
 #include <asm/processor.h>

kernel/locking/lockdep.c

@@ -556,9 +556,9 @@ static void print_lock(struct held_lock *hlock)
 		return;
 	}
 
+	printk(KERN_CONT "%p", hlock->instance);
 	print_lock_name(lock_classes + class_idx - 1);
-	printk(KERN_CONT ", at: [<%p>] %pS\n",
-		(void *)hlock->acquire_ip, (void *)hlock->acquire_ip);
+	printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip);
 }
 
 static void lockdep_print_held_locks(struct task_struct *curr)
@@ -808,7 +808,7 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
 	if (verbose(class)) {
 		graph_unlock();
 
-		printk("\nnew class %p: %s", class->key, class->name);
+		printk("\nnew class %px: %s", class->key, class->name);
 		if (class->name_version > 1)
 			printk(KERN_CONT "#%d", class->name_version);
 		printk(KERN_CONT "\n");
@@ -1407,7 +1407,7 @@ static void print_lock_class_header(struct lock_class *class, int depth)
 	}
 	printk("%*s }\n", depth, "");
 
-	printk("%*s ... key      at: [<%p>] %pS\n",
+	printk("%*s ... key      at: [<%px>] %pS\n",
 		depth, "", class->key, class->key);
 }
 
@@ -2340,7 +2340,7 @@ static inline int lookup_chain_cache_add(struct task_struct *curr,
 
 		if (very_verbose(class)) {
 			printk("\nhash chain already cached, key: "
-					"%016Lx tail class: [%p] %s\n",
+					"%016Lx tail class: [%px] %s\n",
 					(unsigned long long)chain_key,
 					class->key, class->name);
 		}
@@ -2349,7 +2349,7 @@ static inline int lookup_chain_cache_add(struct task_struct *curr,
 	}
 
 	if (very_verbose(class)) {
-		printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
+		printk("\nnew hash chain, key: %016Lx tail class: [%px] %s\n",
 			(unsigned long long)chain_key, class->key, class->name);
 	}
 
@@ -2676,16 +2676,16 @@ check_usage_backwards(struct task_struct *curr, struct held_lock *this,
 void print_irqtrace_events(struct task_struct *curr)
 {
 	printk("irq event stamp: %u\n", curr->irq_events);
-	printk("hardirqs last  enabled at (%u): [<%p>] %pS\n",
+	printk("hardirqs last  enabled at (%u): [<%px>] %pS\n",
 		curr->hardirq_enable_event, (void *)curr->hardirq_enable_ip,
 		(void *)curr->hardirq_enable_ip);
-	printk("hardirqs last disabled at (%u): [<%p>] %pS\n",
+	printk("hardirqs last disabled at (%u): [<%px>] %pS\n",
 		curr->hardirq_disable_event, (void *)curr->hardirq_disable_ip,
 		(void *)curr->hardirq_disable_ip);
-	printk("softirqs last  enabled at (%u): [<%p>] %pS\n",
+	printk("softirqs last  enabled at (%u): [<%px>] %pS\n",
 		curr->softirq_enable_event, (void *)curr->softirq_enable_ip,
 		(void *)curr->softirq_enable_ip);
-	printk("softirqs last disabled at (%u): [<%p>] %pS\n",
+	printk("softirqs last disabled at (%u): [<%px>] %pS\n",
 		curr->softirq_disable_event, (void *)curr->softirq_disable_ip,
 		(void *)curr->softirq_disable_ip);
 }
@@ -3207,7 +3207,7 @@ static void __lockdep_init_map(struct lockdep_map *lock, const char *name,
 	 * Sanity check, the lock-class key must be persistent:
 	 */
 	if (!static_obj(key)) {
-		printk("BUG: key %p not in .data!\n", key);
+		printk("BUG: key %px not in .data!\n", key);
 		/*
 		 * What it says above ^^^^^, I suggest you read it.
 		 */
@@ -3322,7 +3322,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 	}
 	atomic_inc((atomic_t *)&class->ops);
 	if (very_verbose(class)) {
-		printk("\nacquire class [%p] %s", class->key, class->name);
+		printk("\nacquire class [%px] %s", class->key, class->name);
 		if (class->name_version > 1)
 			printk(KERN_CONT "#%d", class->name_version);
 		printk(KERN_CONT "\n");
@@ -4376,7 +4376,7 @@ print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
 	pr_warn("WARNING: held lock freed!\n");
 	print_kernel_ident();
 	pr_warn("-------------------------\n");
-	pr_warn("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
+	pr_warn("%s/%d is freeing memory %px-%px, with a lock still held there!\n",
 		curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
 	print_lock(hlock);
 	lockdep_print_held_locks(curr);

kernel/locking/rtmutex.c

@@ -1268,7 +1268,6 @@ rt_mutex_slowlock(struct rt_mutex *lock, int state,
 
 	if (unlikely(ret)) {
 		__set_current_state(TASK_RUNNING);
-		if (rt_mutex_has_waiters(lock))
 		remove_waiter(lock, &waiter);
 		rt_mutex_handle_deadlock(ret, chwalk, &waiter);
 	}

kernel/locking/rtmutex_common.h

@@ -52,12 +52,13 @@ static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
 static inline struct rt_mutex_waiter *
 rt_mutex_top_waiter(struct rt_mutex *lock)
 {
-	struct rt_mutex_waiter *w;
+	struct rb_node *leftmost = rb_first_cached(&lock->waiters);
+	struct rt_mutex_waiter *w = NULL;
 
-	w = rb_entry(lock->waiters.rb_leftmost,
-		     struct rt_mutex_waiter, tree_entry);
+	if (leftmost) {
+		w = rb_entry(leftmost, struct rt_mutex_waiter, tree_entry);
 		BUG_ON(w->lock != lock);
-
+	}
 	return w;
 }
 

kernel/locking/rwsem.c

@@ -117,6 +117,7 @@ EXPORT_SYMBOL(down_write_trylock);
 void up_read(struct rw_semaphore *sem)
 {
 	rwsem_release(&sem->dep_map, 1, _RET_IP_);
+	DEBUG_RWSEMS_WARN_ON(sem->owner != RWSEM_READER_OWNED);
 
 	__up_read(sem);
 }
@@ -129,6 +130,7 @@ EXPORT_SYMBOL(up_read);
 void up_write(struct rw_semaphore *sem)
 {
 	rwsem_release(&sem->dep_map, 1, _RET_IP_);
+	DEBUG_RWSEMS_WARN_ON(sem->owner != current);
 
 	rwsem_clear_owner(sem);
 	__up_write(sem);
@@ -142,6 +144,7 @@ EXPORT_SYMBOL(up_write);
 void downgrade_write(struct rw_semaphore *sem)
 {
 	lock_downgrade(&sem->dep_map, _RET_IP_);
+	DEBUG_RWSEMS_WARN_ON(sem->owner != current);
 
 	rwsem_set_reader_owned(sem);
 	__downgrade_write(sem);
@@ -211,6 +214,7 @@ EXPORT_SYMBOL(down_write_killable_nested);
 
 void up_read_non_owner(struct rw_semaphore *sem)
 {
+	DEBUG_RWSEMS_WARN_ON(sem->owner != RWSEM_READER_OWNED);
 	__up_read(sem);
 }
 

kernel/locking/rwsem.h

@@ -16,6 +16,12 @@
  */
 #define RWSEM_READER_OWNED	((struct task_struct *)1UL)
 
+#ifdef CONFIG_DEBUG_RWSEMS
+# define DEBUG_RWSEMS_WARN_ON(c)	DEBUG_LOCKS_WARN_ON(c)
+#else
+# define DEBUG_RWSEMS_WARN_ON(c)
+#endif
+
 #ifdef CONFIG_RWSEM_SPIN_ON_OWNER
 /*
  * All writes to owner are protected by WRITE_ONCE() to make sure that
@@ -41,7 +47,7 @@ static inline void rwsem_set_reader_owned(struct rw_semaphore *sem)
 	 * do a write to the rwsem cacheline when it is really necessary
 	 * to minimize cacheline contention.
 	 */
-	if (sem->owner != RWSEM_READER_OWNED)
+	if (READ_ONCE(sem->owner) != RWSEM_READER_OWNED)
 		WRITE_ONCE(sem->owner, RWSEM_READER_OWNED);
 }
 

lib/Kconfig.debug

@@ -1034,69 +1034,20 @@ config DEBUG_PREEMPT
 
 menu "Lock Debugging (spinlocks, mutexes, etc...)"
 
-config DEBUG_RT_MUTEXES
-	bool "RT Mutex debugging, deadlock detection"
-	depends on DEBUG_KERNEL && RT_MUTEXES
-	help
-	 This allows rt mutex semantics violations and rt mutex related
-	 deadlocks (lockups) to be detected and reported automatically.
-
-config DEBUG_SPINLOCK
-	bool "Spinlock and rw-lock debugging: basic checks"
-	depends on DEBUG_KERNEL
-	select UNINLINE_SPIN_UNLOCK
-	help
-	  Say Y here and build SMP to catch missing spinlock initialization
-	  and certain other kinds of spinlock errors commonly made.  This is
-	  best used in conjunction with the NMI watchdog so that spinlock
-	  deadlocks are also debuggable.
-
-config DEBUG_MUTEXES
-	bool "Mutex debugging: basic checks"
-	depends on DEBUG_KERNEL
-	help
-	 This feature allows mutex semantics violations to be detected and
-	 reported.
-
-config DEBUG_WW_MUTEX_SLOWPATH
-	bool "Wait/wound mutex debugging: Slowpath testing"
-	depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
-	select DEBUG_LOCK_ALLOC
-	select DEBUG_SPINLOCK
-	select DEBUG_MUTEXES
-	help
-	 This feature enables slowpath testing for w/w mutex users by
-	 injecting additional -EDEADLK wound/backoff cases. Together with
-	 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
-	 will test all possible w/w mutex interface abuse with the
-	 exception of simply not acquiring all the required locks.
-	 Note that this feature can introduce significant overhead, so
-	 it really should not be enabled in a production or distro kernel,
-	 even a debug kernel.  If you are a driver writer, enable it.  If
-	 you are a distro, do not.
-
-config DEBUG_LOCK_ALLOC
-	bool "Lock debugging: detect incorrect freeing of live locks"
-	depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
-	select DEBUG_SPINLOCK
-	select DEBUG_MUTEXES
-	select DEBUG_RT_MUTEXES if RT_MUTEXES
-	select LOCKDEP
-	help
-	 This feature will check whether any held lock (spinlock, rwlock,
-	 mutex or rwsem) is incorrectly freed by the kernel, via any of the
-	 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
-	 vfree(), etc.), whether a live lock is incorrectly reinitialized via
-	 spin_lock_init()/mutex_init()/etc., or whether there is any lock
-	 held during task exit.
+config LOCK_DEBUGGING_SUPPORT
+	bool
+	depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
+	default y
 
 config PROVE_LOCKING
 	bool "Lock debugging: prove locking correctness"
-	depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
+	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
 	select LOCKDEP
 	select DEBUG_SPINLOCK
 	select DEBUG_MUTEXES
 	select DEBUG_RT_MUTEXES if RT_MUTEXES
+	select DEBUG_RWSEMS if RWSEM_SPIN_ON_OWNER
+	select DEBUG_WW_MUTEX_SLOWPATH
 	select DEBUG_LOCK_ALLOC
 	select TRACE_IRQFLAGS
 	default n
@@ -1134,20 +1085,9 @@ config PROVE_LOCKING
 
 	 For more details, see Documentation/locking/lockdep-design.txt.
 
-config LOCKDEP
-	bool
-	depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
-	select STACKTRACE
-	select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE && !X86
-	select KALLSYMS
-	select KALLSYMS_ALL
-
-config LOCKDEP_SMALL
-	bool
-
 config LOCK_STAT
 	bool "Lock usage statistics"
-	depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
+	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
 	select LOCKDEP
 	select DEBUG_SPINLOCK
 	select DEBUG_MUTEXES
@@ -1167,6 +1107,80 @@ config LOCK_STAT
 	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
 	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
 
+config DEBUG_RT_MUTEXES
+	bool "RT Mutex debugging, deadlock detection"
+	depends on DEBUG_KERNEL && RT_MUTEXES
+	help
+	 This allows rt mutex semantics violations and rt mutex related
+	 deadlocks (lockups) to be detected and reported automatically.
+
+config DEBUG_SPINLOCK
+	bool "Spinlock and rw-lock debugging: basic checks"
+	depends on DEBUG_KERNEL
+	select UNINLINE_SPIN_UNLOCK
+	help
+	  Say Y here and build SMP to catch missing spinlock initialization
+	  and certain other kinds of spinlock errors commonly made.  This is
+	  best used in conjunction with the NMI watchdog so that spinlock
+	  deadlocks are also debuggable.
+
+config DEBUG_MUTEXES
+	bool "Mutex debugging: basic checks"
+	depends on DEBUG_KERNEL
+	help
+	 This feature allows mutex semantics violations to be detected and
+	 reported.
+
+config DEBUG_WW_MUTEX_SLOWPATH
+	bool "Wait/wound mutex debugging: Slowpath testing"
+	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
+	select DEBUG_LOCK_ALLOC
+	select DEBUG_SPINLOCK
+	select DEBUG_MUTEXES
+	help
+	 This feature enables slowpath testing for w/w mutex users by
+	 injecting additional -EDEADLK wound/backoff cases. Together with
+	 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
+	 will test all possible w/w mutex interface abuse with the
+	 exception of simply not acquiring all the required locks.
+	 Note that this feature can introduce significant overhead, so
+	 it really should not be enabled in a production or distro kernel,
+	 even a debug kernel.  If you are a driver writer, enable it.  If
+	 you are a distro, do not.
+
+config DEBUG_RWSEMS
+	bool "RW Semaphore debugging: basic checks"
+	depends on DEBUG_KERNEL && RWSEM_SPIN_ON_OWNER
+	help
+	  This debugging feature allows mismatched rw semaphore locks and unlocks
+	  to be detected and reported.
+
+config DEBUG_LOCK_ALLOC
+	bool "Lock debugging: detect incorrect freeing of live locks"
+	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
+	select DEBUG_SPINLOCK
+	select DEBUG_MUTEXES
+	select DEBUG_RT_MUTEXES if RT_MUTEXES
+	select LOCKDEP
+	help
+	 This feature will check whether any held lock (spinlock, rwlock,
+	 mutex or rwsem) is incorrectly freed by the kernel, via any of the
+	 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
+	 vfree(), etc.), whether a live lock is incorrectly reinitialized via
+	 spin_lock_init()/mutex_init()/etc., or whether there is any lock
+	 held during task exit.
+
+config LOCKDEP
+	bool
+	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
+	select STACKTRACE
+	select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE && !X86
+	select KALLSYMS
+	select KALLSYMS_ALL
+
+config LOCKDEP_SMALL
+	bool
+
 config DEBUG_LOCKDEP
 	bool "Lock dependency engine debugging"
 	depends on DEBUG_KERNEL && LOCKDEP

tools/memory-model/Documentation/cheatsheet.txt

+                                  Prior Operation     Subsequent Operation
+                                  ---------------  ---------------------------
+                               C  Self  R  W  RWM  Self  R  W  DR  DW  RMW  SV
+                              --  ----  -  -  ---  ----  -  -  --  --  ---  --
+
+Store, e.g., WRITE_ONCE()            Y                                       Y
+Load, e.g., READ_ONCE()              Y                          Y   Y        Y
+Unsuccessful RMW operation           Y                          Y   Y        Y
+rcu_dereference()                    Y                          Y   Y        Y
+Successful *_acquire()               R                   Y  Y   Y   Y    Y   Y
+Successful *_release()         C        Y  Y    Y     W                      Y
+smp_rmb()                               Y       R        Y      Y        R
+smp_wmb()                                  Y    W           Y       Y    W
+smp_mb() & synchronize_rcu()  CP        Y  Y    Y        Y  Y   Y   Y    Y
+Successful full non-void RMW  CP     Y  Y  Y    Y     Y  Y  Y   Y   Y    Y   Y
+smp_mb__before_atomic()       CP        Y  Y    Y        a  a   a   a    Y
+smp_mb__after_atomic()        CP        a  a    Y        Y  Y   Y   Y
+
+
+Key:	C:	Ordering is cumulative
+	P:	Ordering propagates
+	R:	Read, for example, READ_ONCE(), or read portion of RMW
+	W:	Write, for example, WRITE_ONCE(), or write portion of RMW
+	Y:	Provides ordering
+	a:	Provides ordering given intervening RMW atomic operation
+	DR:	Dependent read (address dependency)
+	DW:	Dependent write (address, data, or control dependency)
+	RMW:	Atomic read-modify-write operation
+	SV	Same-variable access

tools/memory-model/Documentation/references.txt

+This document provides background reading for memory models and related
+tools.  These documents are aimed at kernel hackers who are interested
+in memory models.
+
+
+Hardware manuals and models
+===========================
+
+o	SPARC International Inc. (Ed.). 1994. "The SPARC Architecture
+	Reference Manual Version 9". SPARC International Inc.
+
+o	Compaq Computer Corporation (Ed.). 2002. "Alpha Architecture
+	Reference Manual".  Compaq Computer Corporation.
+
+o	Intel Corporation (Ed.). 2002. "A Formal Specification of Intel
+	Itanium Processor Family Memory Ordering". Intel Corporation.
+
+o	Intel Corporation (Ed.). 2002. "Intel 64 and IA-32 Architectures
+	Software Developer’s Manual". Intel Corporation.
+
+o	Peter Sewell, Susmit Sarkar, Scott Owens, Francesco Zappa Nardelli,
+	and Magnus O. Myreen. 2010. "x86-TSO: A Rigorous and Usable
+	Programmer's Model for x86 Multiprocessors". Commun. ACM 53, 7
+	(July, 2010), 89-97. http://doi.acm.org/10.1145/1785414.1785443
+
+o	IBM Corporation (Ed.). 2009. "Power ISA Version 2.06". IBM
+	Corporation.
+
+o	ARM Ltd. (Ed.). 2009. "ARM Barrier Litmus Tests and Cookbook".
+	ARM Ltd.
+
+o	Susmit Sarkar, Peter Sewell, Jade Alglave, Luc Maranget, and
+	Derek Williams.  2011. "Understanding POWER Multiprocessors". In
+	Proceedings of the 32Nd ACM SIGPLAN Conference on Programming
+	Language Design and Implementation (PLDI ’11). ACM, New York,
+	NY, USA, 175–186.
+
+o	Susmit Sarkar, Kayvan Memarian, Scott Owens, Mark Batty,
+	Peter Sewell, Luc Maranget, Jade Alglave, and Derek Williams.
+	2012. "Synchronising C/C++ and POWER". In Proceedings of the 33rd
+	ACM SIGPLAN Conference on Programming Language Design and
+	Implementation (PLDI '12). ACM, New York, NY, USA, 311-322.
+
+o	ARM Ltd. (Ed.). 2014. "ARM Architecture Reference Manual (ARMv8,
+	for ARMv8-A architecture profile)". ARM Ltd.
+
+o	Imagination Technologies, LTD. 2015. "MIPS(R) Architecture
+	For Programmers, Volume II-A: The MIPS64(R) Instruction,
+	Set Reference Manual". Imagination Technologies,
+	LTD. https://imgtec.com/?do-download=4302.
+
+o	Shaked Flur, Kathryn E. Gray, Christopher Pulte, Susmit
+	Sarkar, Ali Sezgin, Luc Maranget, Will Deacon, and Peter
+	Sewell. 2016. "Modelling the ARMv8 Architecture, Operationally:
+	Concurrency and ISA". In Proceedings of the 43rd Annual ACM
+	SIGPLAN-SIGACT Symposium on Principles of Programming Languages
+	(POPL ’16). ACM, New York, NY, USA, 608–621.
+
+o	Shaked Flur, Susmit Sarkar, Christopher Pulte, Kyndylan Nienhuis,
+	Luc Maranget, Kathryn E. Gray, Ali Sezgin, Mark Batty, and Peter
+	Sewell. 2017. "Mixed-size Concurrency: ARM, POWER, C/C++11,
+	and SC". In Proceedings of the 44th ACM SIGPLAN Symposium on
+	Principles of Programming Languages (POPL 2017). ACM, New York,
+	NY, USA, 429–442.
+
+
+Linux-kernel memory model
+=========================
+
+o	Andrea Parri, Alan Stern, Luc Maranget, Paul E. McKenney,
+	and Jade Alglave.  2017. "A formal model of
+	Linux-kernel memory ordering - companion webpage".
+	http://moscova.inria.fr/∼maranget/cats7/linux/. (2017). [Online;
+	accessed 30-January-2017].
+
+o	Jade Alglave, Luc Maranget, Paul E. McKenney, Andrea Parri, and
+	Alan Stern.  2017.  "A formal kernel memory-ordering model (part 1)"
+	Linux Weekly News.  https://lwn.net/Articles/718628/
+
+o	Jade Alglave, Luc Maranget, Paul E. McKenney, Andrea Parri, and
+	Alan Stern.  2017.  "A formal kernel memory-ordering model (part 2)"
+	Linux Weekly News.  https://lwn.net/Articles/720550/
+
+
+Memory-model tooling
+====================
+
+o	Daniel Jackson. 2002. "Alloy: A Lightweight Object Modelling
+	Notation". ACM Trans. Softw. Eng. Methodol. 11, 2 (April 2002),
+	256–290. http://doi.acm.org/10.1145/505145.505149
+
+o	Jade Alglave, Luc Maranget, and Michael Tautschnig. 2014. "Herding
+	Cats: Modelling, Simulation, Testing, and Data Mining for Weak
+	Memory". ACM Trans. Program. Lang. Syst. 36, 2, Article 7 (July
+	2014), 7:1–7:74 pages.
+
+o	Jade Alglave, Patrick Cousot, and Luc Maranget. 2016. "Syntax and
+	semantics of the weak consistency model specification language
+	cat". CoRR abs/1608.07531 (2016). http://arxiv.org/abs/1608.07531
+
+
+Memory-model comparisons
+========================
+
+o	Paul E. McKenney, Ulrich Weigand, Andrea Parri, and Boqun
+	Feng. 2016. "Linux-Kernel Memory Model". (6 June 2016).
+	http://open-std.org/JTC1/SC22/WG21/docs/papers/2016/p0124r2.html.

tools/memory-model/README

+		=====================================
+		LINUX KERNEL MEMORY CONSISTENCY MODEL
+		=====================================
+
+============
+INTRODUCTION
+============
+
+This directory contains the memory consistency model (memory model, for
+short) of the Linux kernel, written in the "cat" language and executable
+by the externally provided "herd7" simulator, which exhaustively explores
+the state space of small litmus tests.
+
+In addition, the "klitmus7" tool (also externally provided) may be used
+to convert a litmus test to a Linux kernel module, which in turn allows
+that litmus test to be exercised within the Linux kernel.
+
+
+============
+REQUIREMENTS
+============
+
+Version 7.48 of the "herd7" and "klitmus7" tools must be downloaded
+separately:
+
+  https://github.com/herd/herdtools7
+
+See "herdtools7/INSTALL.md" for installation instructions.
+
+
+==================
+BASIC USAGE: HERD7
+==================
+
+The memory model is used, in conjunction with "herd7", to exhaustively
+explore the state space of small litmus tests.
+
+For example, to run SB+mbonceonces.litmus against the memory model:
+
+  $ herd7 -conf linux-kernel.cfg litmus-tests/SB+mbonceonces.litmus
+
+Here is the corresponding output:
+
+  Test SB+mbonceonces Allowed
+  States 3
+  0:r0=0; 1:r0=1;
+  0:r0=1; 1:r0=0;
+  0:r0=1; 1:r0=1;
+  No
+  Witnesses
+  Positive: 0 Negative: 3
+  Condition exists (0:r0=0 /\ 1:r0=0)
+  Observation SB+mbonceonces Never 0 3
+  Time SB+mbonceonces 0.01
+  Hash=d66d99523e2cac6b06e66f4c995ebb48
+
+The "Positive: 0 Negative: 3" and the "Never 0 3" each indicate that
+this litmus test's "exists" clause can not be satisfied.
+
+See "herd7 -help" or "herdtools7/doc/" for more information.
+
+
+=====================
+BASIC USAGE: KLITMUS7
+=====================
+
+The "klitmus7" tool converts a litmus test into a Linux kernel module,
+which may then be loaded and run.
+
+For example, to run SB+mbonceonces.litmus against hardware:
+
+  $ mkdir mymodules
+  $ klitmus7 -o mymodules litmus-tests/SB+mbonceonces.litmus
+  $ cd mymodules ; make
+  $ sudo sh run.sh
+
+The corresponding output includes:
+
+  Test SB+mbonceonces Allowed
+  Histogram (3 states)
+  644580  :>0:r0=1; 1:r0=0;
+  644328  :>0:r0=0; 1:r0=1;
+  711092  :>0:r0=1; 1:r0=1;
+  No
+  Witnesses
+  Positive: 0, Negative: 2000000
+  Condition exists (0:r0=0 /\ 1:r0=0) is NOT validated
+  Hash=d66d99523e2cac6b06e66f4c995ebb48
+  Observation SB+mbonceonces Never 0 2000000
+  Time SB+mbonceonces 0.16
+
+The "Positive: 0 Negative: 2000000" and the "Never 0 2000000" indicate
+that during two million trials, the state specified in this litmus
+test's "exists" clause was not reached.
+
+And, as with "herd7", please see "klitmus7 -help" or "herdtools7/doc/"
+for more information.
+
+
+====================
+DESCRIPTION OF FILES
+====================
+
+Documentation/cheatsheet.txt
+	Quick-reference guide to the Linux-kernel memory model.
+
+Documentation/explanation.txt
+	Describes the memory model in detail.
+
+Documentation/recipes.txt
+	Lists common memory-ordering patterns.
+
+Documentation/references.txt
+	Provides background reading.
+
+linux-kernel.bell
+	Categorizes the relevant instructions, including memory
+	references, memory barriers, atomic read-modify-write operations,
+	lock acquisition/release, and RCU operations.
+
+	More formally, this file (1) lists the subtypes of the various
+	event types used by the memory model and (2) performs RCU
+	read-side critical section nesting analysis.
+
+linux-kernel.cat
+	Specifies what reorderings are forbidden by memory references,
+	memory barriers, atomic read-modify-write operations, and RCU.
+
+	More formally, this file specifies what executions are forbidden
+	by the memory model.  Allowed executions are those which
+	satisfy the model's "coherence", "atomic", "happens-before",
+	"propagation", and "rcu" axioms, which are defined in the file.
+
+linux-kernel.cfg
+	Convenience file that gathers the common-case herd7 command-line
+	arguments.
+
+linux-kernel.def
+	Maps from C-like syntax to herd7's internal litmus-test
+	instruction-set architecture.
+
+litmus-tests
+	Directory containing a few representative litmus tests, which
+	are listed in litmus-tests/README.  A great deal more litmus
+	tests are available at https://github.com/paulmckrcu/litmus.
+
+lock.cat
+	Provides a front-end analysis of lock acquisition and release,
+	for example, associating a lock acquisition with the preceding
+	and following releases and checking for self-deadlock.
+
+	More formally, this file defines a performance-enhanced scheme
+	for generation of the possible reads-from and coherence order
+	relations on the locking primitives.
+
+README
+	This file.
+
+
+===========
+LIMITATIONS
+===========
+
+The Linux-kernel memory model has the following limitations:
+
+1.	Compiler optimizations are not modeled.  Of course, the use
+	of READ_ONCE() and WRITE_ONCE() limits the compiler's ability
+	to optimize, but there is Linux-kernel code that uses bare C
+	memory accesses.  Handling this code is on the to-do list.
+	For more information, see Documentation/explanation.txt (in
+	particular, the "THE PROGRAM ORDER RELATION: po AND po-loc"
+	and "A WARNING" sections).
+
+2.	Multiple access sizes for a single variable are not supported,
+	and neither are misaligned or partially overlapping accesses.
+
+3.	Exceptions and interrupts are not modeled.  In some cases,
+	this limitation can be overcome by modeling the interrupt or
+	exception with an additional process.
+
+4.	I/O such as MMIO or DMA is not supported.
+
+5.	Self-modifying code (such as that found in the kernel's
+	alternatives mechanism, function tracer, Berkeley Packet Filter
+	JIT compiler, and module loader) is not supported.
+
+6.	Complete modeling of all variants of atomic read-modify-write
+	operations, locking primitives, and RCU is not provided.
+	For example, call_rcu() and rcu_barrier() are not supported.
+	However, a substantial amount of support is provided for these
+	operations, as shown in the linux-kernel.def file.
+
+The "herd7" tool has some additional limitations of its own, apart from
+the memory model:
+
+1.	Non-trivial data structures such as arrays or structures are
+	not supported.	However, pointers are supported, allowing trivial
+	linked lists to be constructed.
+
+2.	Dynamic memory allocation is not supported, although this can
+	be worked around in some cases by supplying multiple statically
+	allocated variables.
+
+Some of these limitations may be overcome in the future, but others are
+more likely to be addressed by incorporating the Linux-kernel memory model
+into other tools.

tools/memory-model/linux-kernel.bell

+// SPDX-License-Identifier: GPL-2.0+
+(*
+ * Copyright (C) 2015 Jade Alglave <j.alglave@ucl.ac.uk>,
+ * Copyright (C) 2016 Luc Maranget <luc.maranget@inria.fr> for Inria
+ * Copyright (C) 2017 Alan Stern <stern@rowland.harvard.edu>,
+ *                    Andrea Parri <parri.andrea@gmail.com>
+ *
+ * An earlier version of this file appears in the companion webpage for
+ * "Frightening small children and disconcerting grown-ups: Concurrency
+ * in the Linux kernel" by Alglave, Maranget, McKenney, Parri, and Stern,
+ * which is to appear in ASPLOS 2018.
+ *)
+
+"Linux-kernel memory consistency model"
+
+enum Accesses = 'once (*READ_ONCE,WRITE_ONCE,ACCESS_ONCE*) ||
+		'release (*smp_store_release*) ||
+		'acquire (*smp_load_acquire*) ||
+		'noreturn (* R of non-return RMW *)
+instructions R[{'once,'acquire,'noreturn}]
+instructions W[{'once,'release}]
+instructions RMW[{'once,'acquire,'release}]
+
+enum Barriers = 'wmb (*smp_wmb*) ||
+		'rmb (*smp_rmb*) ||
+		'mb (*smp_mb*) ||
+		'rcu-lock (*rcu_read_lock*)  ||
+		'rcu-unlock (*rcu_read_unlock*) ||
+		'sync-rcu (*synchronize_rcu*) ||
+		'before-atomic (*smp_mb__before_atomic*) ||
+		'after-atomic (*smp_mb__after_atomic*) ||
+		'after-spinlock (*smp_mb__after_spinlock*)
+instructions F[Barriers]
+
+(* Compute matching pairs of nested Rcu-lock and Rcu-unlock *)
+let matched = let rec
+	    unmatched-locks = Rcu-lock \ domain(matched)
+	and unmatched-unlocks = Rcu-unlock \ range(matched)
+	and unmatched = unmatched-locks | unmatched-unlocks
+	and unmatched-po = [unmatched] ; po ; [unmatched]
+	and unmatched-locks-to-unlocks =
+		[unmatched-locks] ; po ; [unmatched-unlocks]
+	and matched = matched | (unmatched-locks-to-unlocks \
+		(unmatched-po ; unmatched-po))
+	in matched
+
+(* Validate nesting *)
+flag ~empty Rcu-lock \ domain(matched) as unbalanced-rcu-locking
+flag ~empty Rcu-unlock \ range(matched) as unbalanced-rcu-locking
+
+(* Outermost level of nesting only *)
+let crit = matched \ (po^-1 ; matched ; po^-1)