Commit ec332cd3 authored by Robert Love's avatar Robert Love Committed by Linus Torvalds

[PATCH] Re: [PATCH] Preemptible Kernel for 2.5

On Sat, 2002-02-09 at 01:43, Linus Torvalds wrote:

> That will clean up all your issues with header file ordering.

You are right, it did.  I removed all the sched.h dependencies and this
reduced the size of the patch greatly.  I now use current_thread_info()
and none of the header or include hackery from before.  I've tested this
with and without preemption enabled with success.

I appreciate your help with this.

Again, this is a minimal i386-only patch.  I have other arches,
documentation, etc.  Patch against 2.5.4-pre5.  Enjoy,

	Robert Love
parent d7b65475
......@@ -25,6 +25,16 @@ CONFIG_SMP
If you don't know what to do here, say N.
CONFIG_PREEMPT
This option reduces the latency of the kernel when reacting to
real-time or interactive events by allowing a low priority process to
be preempted even if it is in kernel mode executing a system call.
This allows applications to run more reliably even when the system is
under load.
Say Y here if you are building a kernel for a desktop, embedded
or real-time system. Say N if you are unsure.
CONFIG_X86
This is Linux's home port. Linux was originally native to the Intel
386, and runs on all the later x86 processors including the Intel
......
......@@ -167,6 +167,7 @@ fi
bool 'Math emulation' CONFIG_MATH_EMULATION
bool 'MTRR (Memory Type Range Register) support' CONFIG_MTRR
bool 'Symmetric multi-processing support' CONFIG_SMP
bool 'Preemptible Kernel' CONFIG_PREEMPT
if [ "$CONFIG_SMP" != "y" ]; then
bool 'Local APIC support on uniprocessors' CONFIG_X86_UP_APIC
dep_bool 'IO-APIC support on uniprocessors' CONFIG_X86_UP_IOAPIC $CONFIG_X86_UP_APIC
......@@ -180,9 +181,12 @@ else
bool 'Multiquad NUMA system' CONFIG_MULTIQUAD
fi
if [ "$CONFIG_SMP" = "y" -a "$CONFIG_X86_CMPXCHG" = "y" ]; then
if [ "$CONFIG_SMP" = "y" -o "$CONFIG_PREEMPT" = "y" ]; then
if [ "$CONFIG_X86_CMPXCHG" = "y" ]; then
define_bool CONFIG_HAVE_DEC_LOCK y
fi
fi
endmenu
mainmenu_option next_comment
......
......@@ -69,6 +69,37 @@ IF_MASK = 0x00000200
NT_MASK = 0x00004000
VM_MASK = 0x00020000
/* These are offsets into the irq_stat structure
* There is one per cpu and it is aligned to 32
* byte boundry (we put that here as a shift count)
*/
irq_array_shift = CONFIG_X86_L1_CACHE_SHIFT
irq_stat_local_irq_count = 4
irq_stat_local_bh_count = 8
#ifdef CONFIG_SMP
#define GET_CPU_INDX movl TI_CPU(%ebx),%eax; \
shll $irq_array_shift,%eax
#define GET_CURRENT_CPU_INDX GET_THREAD_INFO(%ebx); \
GET_CPU_INDX
#define CPU_INDX (,%eax)
#else
#define GET_CPU_INDX
#define GET_CURRENT_CPU_INDX GET_THREAD_INFO(%ebx)
#define CPU_INDX
#endif
#ifdef CONFIG_PREEMPT
#define preempt_stop cli
#define init_ret_intr \
cli; \
decl TI_PRE_COUNT(%ebx);
#else
#define preempt_stop
#define init_ret_intr
#define resume_kernel restore_all
#endif
#define SAVE_ALL \
cld; \
pushl %es; \
......@@ -176,11 +207,12 @@ ENTRY(ret_from_fork)
ALIGN
ENTRY(ret_from_intr)
GET_THREAD_INFO(%ebx)
init_ret_intr
ret_from_exception:
movl EFLAGS(%esp),%eax # mix EFLAGS and CS
movb CS(%esp),%al
testl $(VM_MASK | 3),%eax
jz restore_all # returning to kernel-space or vm86-space
jz resume_kernel # returning to kernel or vm86-space
ENTRY(resume_userspace)
cli # make sure we don't miss an interrupt setting need_resched
# or sigpending between sampling and the iret
......@@ -189,6 +221,22 @@ ENTRY(resume_userspace)
jne work_pending
jmp restore_all
#ifdef CONFIG_PREEMPT
ENTRY(resume_kernel)
cmpl $0,TI_PRE_COUNT(%ebx)
jnz restore_all
movl TI_FLAGS(%ebx),%ecx
testb $_TIF_NEED_RESCHED,%cl
jz restore_all
movl SYMBOL_NAME(irq_stat)+irq_stat_local_bh_count CPU_INDX,%ecx
addl SYMBOL_NAME(irq_stat)+irq_stat_local_irq_count CPU_INDX,%ecx
jnz restore_all
incl TI_PRE_COUNT(%ebx)
sti
call SYMBOL_NAME(preempt_schedule)
jmp ret_from_intr
#endif
# system call handler stub
ALIGN
ENTRY(system_call)
......@@ -302,6 +350,7 @@ error_code:
GET_THREAD_INFO(%ebx)
call *%edi
addl $8,%esp
preempt_stop
jmp ret_from_exception
ENTRY(coprocessor_error)
......@@ -321,12 +370,14 @@ ENTRY(device_not_available)
movl %cr0,%eax
testl $0x4,%eax # EM (math emulation bit)
jne device_not_available_emulate
preempt_stop
call SYMBOL_NAME(math_state_restore)
jmp ret_from_exception
device_not_available_emulate:
pushl $0 # temporary storage for ORIG_EIP
call SYMBOL_NAME(math_emulate)
addl $4,%esp
preempt_stop
jmp ret_from_exception
ENTRY(debug)
......
......@@ -10,6 +10,7 @@
#include <linux/config.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <asm/processor.h>
#include <asm/i387.h>
#include <asm/math_emu.h>
......@@ -63,6 +64,7 @@ void save_init_fpu( struct task_struct *tsk )
void kernel_fpu_begin(void)
{
preempt_disable();
if (test_thread_flag(TIF_USEDFPU)) {
__save_init_fpu(current);
return;
......
......@@ -497,7 +497,7 @@ void smp_migrate_task(int cpu, task_t *p)
/*
* The target CPU will unlock the migration spinlock:
*/
spin_lock(&migration_lock);
_raw_spin_lock(&migration_lock);
new_task = p;
send_IPI_mask(1 << cpu, TASK_MIGRATION_VECTOR);
}
......@@ -511,7 +511,7 @@ asmlinkage void smp_task_migration_interrupt(void)
ack_APIC_irq();
p = new_task;
spin_unlock(&migration_lock);
_raw_spin_unlock(&migration_lock);
sched_task_migrated(p);
}
/*
......
......@@ -710,6 +710,8 @@ asmlinkage void do_spurious_interrupt_bug(struct pt_regs * regs,
*
* Careful.. There are problems with IBM-designed IRQ13 behaviour.
* Don't touch unless you *really* know how it works.
*
* Must be called with kernel preemption disabled.
*/
asmlinkage void math_state_restore(struct pt_regs regs)
{
......
......@@ -420,8 +420,8 @@ static int exec_mmap(void)
active_mm = current->active_mm;
current->mm = mm;
current->active_mm = mm;
task_unlock(current);
activate_mm(active_mm, mm);
task_unlock(current);
mm_release();
if (old_mm) {
if (active_mm != old_mm) BUG();
......
......@@ -36,6 +36,8 @@ typedef struct {
#define synchronize_irq() barrier()
#define release_irqlock(cpu) do { } while (0)
#else
#include <asm/atomic.h>
......
......@@ -88,6 +88,7 @@ static inline void *kmap_atomic(struct page *page, enum km_type type)
enum fixed_addresses idx;
unsigned long vaddr;
preempt_disable();
if (page < highmem_start_page)
return page_address(page);
......@@ -109,8 +110,10 @@ static inline void kunmap_atomic(void *kvaddr, enum km_type type)
unsigned long vaddr = (unsigned long) kvaddr;
enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
if (vaddr < FIXADDR_START) // FIXME
if (vaddr < FIXADDR_START) { // FIXME
preempt_enable();
return;
}
if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx))
BUG();
......@@ -122,6 +125,8 @@ static inline void kunmap_atomic(void *kvaddr, enum km_type type)
pte_clear(kmap_pte-idx);
__flush_tlb_one(vaddr);
#endif
preempt_enable();
}
#endif /* __KERNEL__ */
......
......@@ -96,6 +96,18 @@ extern char _stext, _etext;
#define __STR(x) #x
#define STR(x) __STR(x)
#define GET_THREAD_INFO \
"movl $-8192, %ebx\n\t" \
"andl %esp, %ebx\n\t"
#ifdef CONFIG_PREEMPT
#define BUMP_LOCK_COUNT \
GET_THREAD_INFO \
"incl 16(%ebx)\n\t"
#else
#define BUMP_LOCK_COUNT
#endif
#define SAVE_ALL \
"cld\n\t" \
"pushl %es\n\t" \
......@@ -109,7 +121,8 @@ extern char _stext, _etext;
"pushl %ebx\n\t" \
"movl $" STR(__KERNEL_DS) ",%edx\n\t" \
"movl %edx,%ds\n\t" \
"movl %edx,%es\n\t"
"movl %edx,%es\n\t" \
BUMP_LOCK_COUNT
#define IRQ_NAME2(nr) nr##_interrupt(void)
#define IRQ_NAME(nr) IRQ_NAME2(IRQ##nr)
......
......@@ -12,6 +12,7 @@
#define __ASM_I386_I387_H
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <asm/processor.h>
#include <asm/sigcontext.h>
#include <asm/user.h>
......@@ -24,7 +25,7 @@ extern void save_init_fpu( struct task_struct *tsk );
extern void restore_fpu( struct task_struct *tsk );
extern void kernel_fpu_begin(void);
#define kernel_fpu_end() stts()
#define kernel_fpu_end() do { stts(); preempt_enable(); } while(0)
#define unlazy_fpu( tsk ) do { \
......
......@@ -75,20 +75,26 @@ static inline pgd_t *get_pgd_fast(void)
{
unsigned long *ret;
preempt_disable();
if ((ret = pgd_quicklist) != NULL) {
pgd_quicklist = (unsigned long *)(*ret);
ret[0] = 0;
pgtable_cache_size--;
} else
preempt_enable();
} else {
preempt_enable();
ret = (unsigned long *)get_pgd_slow();
}
return (pgd_t *)ret;
}
static inline void free_pgd_fast(pgd_t *pgd)
{
preempt_disable();
*(unsigned long *)pgd = (unsigned long) pgd_quicklist;
pgd_quicklist = (unsigned long *) pgd;
pgtable_cache_size++;
preempt_enable();
}
static inline void free_pgd_slow(pgd_t *pgd)
......@@ -119,19 +125,23 @@ static inline pte_t *pte_alloc_one_fast(struct mm_struct *mm,
{
unsigned long *ret;
preempt_disable();
if ((ret = (unsigned long *)pte_quicklist) != NULL) {
pte_quicklist = (unsigned long *)(*ret);
ret[0] = ret[1];
pgtable_cache_size--;
}
preempt_enable();
return (pte_t *)ret;
}
static inline void pte_free_fast(pte_t *pte)
{
preempt_disable();
*(unsigned long *)pte = (unsigned long) pte_quicklist;
pte_quicklist = (unsigned long *) pte;
pgtable_cache_size++;
preempt_enable();
}
static __inline__ void pte_free_slow(pte_t *pte)
......
......@@ -10,7 +10,15 @@
extern spinlock_t kernel_flag;
#ifdef CONFIG_SMP
#define kernel_locked() spin_is_locked(&kernel_flag)
#else
#ifdef CONFIG_PREEMPT
#define kernel_locked() preempt_get_count()
#else
#define kernel_locked() 1
#endif
#endif
/*
* Release global kernel lock and global interrupt lock
......@@ -43,6 +51,11 @@ do { \
*/
static __inline__ void lock_kernel(void)
{
#ifdef CONFIG_PREEMPT
if (current->lock_depth == -1)
spin_lock(&kernel_flag);
++current->lock_depth;
#else
#if 1
if (!++current->lock_depth)
spin_lock(&kernel_flag);
......@@ -55,6 +68,7 @@ static __inline__ void lock_kernel(void)
:"=m" (__dummy_lock(&kernel_flag)),
"=m" (current->lock_depth));
#endif
#endif
}
static __inline__ void unlock_kernel(void)
......
......@@ -5,9 +5,9 @@
#include <asm/hardirq.h>
#define __cpu_bh_enable(cpu) \
do { barrier(); local_bh_count(cpu)--; } while (0)
do { barrier(); local_bh_count(cpu)--; preempt_enable(); } while (0)
#define cpu_bh_disable(cpu) \
do { local_bh_count(cpu)++; barrier(); } while (0)
do { preempt_disable(); local_bh_count(cpu)++; barrier(); } while (0)
#define local_bh_disable() cpu_bh_disable(smp_processor_id())
#define __local_bh_enable() __cpu_bh_enable(smp_processor_id())
......@@ -22,7 +22,7 @@
* If you change the offsets in irq_stat then you have to
* update this code as well.
*/
#define local_bh_enable() \
#define _local_bh_enable() \
do { \
unsigned int *ptr = &local_bh_count(smp_processor_id()); \
\
......@@ -45,4 +45,6 @@ do { \
/* no registers clobbered */ ); \
} while (0)
#define local_bh_enable() do { _local_bh_enable(); preempt_enable(); } while (0)
#endif /* __ASM_SOFTIRQ_H */
......@@ -77,7 +77,7 @@ typedef struct {
:"=m" (lock->lock) : : "memory"
static inline void spin_unlock(spinlock_t *lock)
static inline void _raw_spin_unlock(spinlock_t *lock)
{
#if SPINLOCK_DEBUG
if (lock->magic != SPINLOCK_MAGIC)
......@@ -97,7 +97,7 @@ static inline void spin_unlock(spinlock_t *lock)
:"=q" (oldval), "=m" (lock->lock) \
:"0" (oldval) : "memory"
static inline void spin_unlock(spinlock_t *lock)
static inline void _raw_spin_unlock(spinlock_t *lock)
{
char oldval = 1;
#if SPINLOCK_DEBUG
......@@ -113,7 +113,7 @@ static inline void spin_unlock(spinlock_t *lock)
#endif
static inline int spin_trylock(spinlock_t *lock)
static inline int _raw_spin_trylock(spinlock_t *lock)
{
char oldval;
__asm__ __volatile__(
......@@ -123,7 +123,7 @@ static inline int spin_trylock(spinlock_t *lock)
return oldval > 0;
}
static inline void spin_lock(spinlock_t *lock)
static inline void _raw_spin_lock(spinlock_t *lock)
{
#if SPINLOCK_DEBUG
__label__ here;
......@@ -179,7 +179,7 @@ typedef struct {
*/
/* the spinlock helpers are in arch/i386/kernel/semaphore.c */
static inline void read_lock(rwlock_t *rw)
static inline void _raw_read_lock(rwlock_t *rw)
{
#if SPINLOCK_DEBUG
if (rw->magic != RWLOCK_MAGIC)
......@@ -188,7 +188,7 @@ static inline void read_lock(rwlock_t *rw)
__build_read_lock(rw, "__read_lock_failed");
}
static inline void write_lock(rwlock_t *rw)
static inline void _raw_write_lock(rwlock_t *rw)
{
#if SPINLOCK_DEBUG
if (rw->magic != RWLOCK_MAGIC)
......@@ -197,10 +197,10 @@ static inline void write_lock(rwlock_t *rw)
__build_write_lock(rw, "__write_lock_failed");
}
#define read_unlock(rw) asm volatile("lock ; incl %0" :"=m" ((rw)->lock) : : "memory")
#define write_unlock(rw) asm volatile("lock ; addl $" RW_LOCK_BIAS_STR ",%0":"=m" ((rw)->lock) : : "memory")
#define _raw_read_unlock(rw) asm volatile("lock ; incl %0" :"=m" ((rw)->lock) : : "memory")
#define _raw_write_unlock(rw) asm volatile("lock ; addl $" RW_LOCK_BIAS_STR ",%0":"=m" ((rw)->lock) : : "memory")
static inline int write_trylock(rwlock_t *lock)
static inline int _raw_write_trylock(rwlock_t *lock)
{
atomic_t *count = (atomic_t *)lock;
if (atomic_sub_and_test(RW_LOCK_BIAS, count))
......
......@@ -25,6 +25,7 @@ struct thread_info {
struct exec_domain *exec_domain; /* execution domain */
__u32 flags; /* low level flags */
__u32 cpu; /* current CPU */
__s32 preempt_count; /* 0 => preemptable, <0 => BUG */
mm_segment_t addr_limit; /* thread address space:
0-0xBFFFFFFF for user-thead
......@@ -41,7 +42,8 @@ struct thread_info {
#define TI_EXEC_DOMAIN 0x00000004
#define TI_FLAGS 0x00000008
#define TI_CPU 0x0000000C
#define TI_ADDR_LIMIT 0x00000010
#define TI_PRE_COUNT 0x00000010
#define TI_ADDR_LIMIT 0x00000014
#endif
......
......@@ -171,11 +171,11 @@ static inline void br_write_unlock (enum brlock_indices idx)
}
#else
# define br_read_lock(idx) ((void)(idx))
# define br_read_unlock(idx) ((void)(idx))
# define br_write_lock(idx) ((void)(idx))
# define br_write_unlock(idx) ((void)(idx))
#endif
# define br_read_lock(idx) ({ (void)(idx); preempt_disable(); })
# define br_read_unlock(idx) ({ (void)(idx); preempt_enable(); })
# define br_write_lock(idx) ({ (void)(idx); preempt_disable(); })
# define br_write_unlock(idx) ({ (void)(idx); preempt_enable(); })
#endif /* CONFIG_SMP */
/*
* Now enumerate all of the possible sw/hw IRQ protected
......
......@@ -91,6 +91,7 @@ extern unsigned long nr_running(void);
#define TASK_UNINTERRUPTIBLE 2
#define TASK_ZOMBIE 4
#define TASK_STOPPED 8
#define PREEMPT_ACTIVE 0x4000000
#define __set_task_state(tsk, state_value) \
do { (tsk)->state = (state_value); } while (0)
......
......@@ -81,7 +81,9 @@ extern volatile int smp_msg_id;
#define smp_processor_id() 0
#define hard_smp_processor_id() 0
#define smp_threads_ready 1
#ifndef CONFIG_PREEMPT
#define kernel_lock()
#endif
#define cpu_logical_map(cpu) 0
#define cpu_number_map(cpu) 0
#define smp_call_function(func,info,retry,wait) ({ 0; })
......
......@@ -3,7 +3,7 @@
#include <linux/config.h>
#ifndef CONFIG_SMP
#if !defined(CONFIG_SMP) && !defined(CONFIG_PREEMPT)
#define lock_kernel() do { } while(0)
#define unlock_kernel() do { } while(0)
......
......@@ -2,6 +2,10 @@
#define __LINUX_SPINLOCK_H
#include <linux/config.h>
#include <linux/linkage.h>
#include <linux/compiler.h>
#include <linux/thread_info.h>
#include <linux/kernel.h>
/*
* These are the generic versions of the spinlocks and read-write
......@@ -62,8 +66,10 @@
#if (DEBUG_SPINLOCKS < 1)
#ifndef CONFIG_PREEMPT
#define atomic_dec_and_lock(atomic,lock) atomic_dec_and_test(atomic)
#define ATOMIC_DEC_AND_LOCK
#endif
/*
* Your basic spinlocks, allowing only a single CPU anywhere
......@@ -79,11 +85,11 @@
#endif
#define spin_lock_init(lock) do { } while(0)
#define spin_lock(lock) (void)(lock) /* Not "unused variable". */
#define _raw_spin_lock(lock) (void)(lock) /* Not "unused variable". */
#define spin_is_locked(lock) (0)
#define spin_trylock(lock) ({1; })
#define _raw_spin_trylock(lock) ({1; })
#define spin_unlock_wait(lock) do { } while(0)
#define spin_unlock(lock) do { } while(0)
#define _raw_spin_unlock(lock) do { } while(0)
#elif (DEBUG_SPINLOCKS < 2)
......@@ -142,13 +148,79 @@ typedef struct {
#endif
#define rwlock_init(lock) do { } while(0)
#define read_lock(lock) (void)(lock) /* Not "unused variable". */
#define read_unlock(lock) do { } while(0)
#define write_lock(lock) (void)(lock) /* Not "unused variable". */
#define write_unlock(lock) do { } while(0)
#define _raw_read_lock(lock) (void)(lock) /* Not "unused variable". */
#define _raw_read_unlock(lock) do { } while(0)
#define _raw_write_lock(lock) (void)(lock) /* Not "unused variable". */
#define _raw_write_unlock(lock) do { } while(0)
#endif /* !SMP */
#ifdef CONFIG_PREEMPT
asmlinkage void preempt_schedule(void);
#define preempt_get_count() (current_thread_info()->preempt_count)
#define preempt_disable() \
do { \
++current_thread_info()->preempt_count; \
barrier(); \
} while (0)
#define preempt_enable_no_resched() \
do { \
--current_thread_info()->preempt_count; \
barrier(); \
} while (0)
#define preempt_enable() \
do { \
--current_thread_info()->preempt_count; \
barrier(); \
if (unlikely(!(current_thread_info()->preempt_count) && \
test_thread_flag(TIF_NEED_RESCHED))) \
preempt_schedule(); \
} while (0)
#define spin_lock(lock) \
do { \
preempt_disable(); \
_raw_spin_lock(lock); \
} while(0)
#define spin_trylock(lock) ({preempt_disable(); _raw_spin_trylock(lock) ? \
1 : ({preempt_enable(); 0;});})
#define spin_unlock(lock) \
do { \
_raw_spin_unlock(lock); \
preempt_enable(); \
} while (0)
#define read_lock(lock) ({preempt_disable(); _raw_read_lock(lock);})
#define read_unlock(lock) ({_raw_read_unlock(lock); preempt_enable();})
#define write_lock(lock) ({preempt_disable(); _raw_write_lock(lock);})
#define write_unlock(lock) ({_raw_write_unlock(lock); preempt_enable();})
#define write_trylock(lock) ({preempt_disable();_raw_write_trylock(lock) ? \
1 : ({preempt_enable(); 0;});})
#else
#define preempt_get_count() do { } while (0)
#define preempt_disable() do { } while (0)
#define preempt_enable_no_resched() do {} while(0)
#define preempt_enable() do { } while (0)
#define spin_lock(lock) _raw_spin_lock(lock)
#define spin_trylock(lock) _raw_spin_trylock(lock)
#define spin_unlock(lock) _raw_spin_unlock(lock)
#define read_lock(lock) _raw_read_lock(lock)
#define read_unlock(lock) _raw_read_unlock(lock)
#define write_lock(lock) _raw_write_lock(lock)
#define write_unlock(lock) _raw_write_unlock(lock)
#define write_trylock(lock) _raw_write_trylock(lock)
#endif
/* "lock on reference count zero" */
#ifndef ATOMIC_DEC_AND_LOCK
#include <asm/atomic.h>
......
......@@ -390,8 +390,8 @@ static inline void __exit_mm(struct task_struct * tsk)
/* more a memory barrier than a real lock */
task_lock(tsk);
tsk->mm = NULL;
task_unlock(tsk);
enter_lazy_tlb(mm, current, smp_processor_id());
task_unlock(tsk);
mmput(mm);
}
}
......
......@@ -650,6 +650,13 @@ int do_fork(unsigned long clone_flags, unsigned long stack_start,
if (p->binfmt && p->binfmt->module)
__MOD_INC_USE_COUNT(p->binfmt->module);
#ifdef CONFIG_PREEMPT
/*
* schedule_tail drops this_rq()->lock so we compensate with a count
* of 1. Also, we want to start with kernel preemption disabled.
*/
p->thread_info->preempt_count = 1;
#endif
p->did_exec = 0;
p->swappable = 0;
p->state = TASK_UNINTERRUPTIBLE;
......
......@@ -445,6 +445,9 @@ EXPORT_SYMBOL(sleep_on_timeout);
EXPORT_SYMBOL(interruptible_sleep_on);
EXPORT_SYMBOL(interruptible_sleep_on_timeout);
EXPORT_SYMBOL(schedule);
#ifdef CONFIG_PREEMPT
EXPORT_SYMBOL(preempt_schedule);
#endif
EXPORT_SYMBOL(schedule_timeout);
EXPORT_SYMBOL(sys_sched_yield);
EXPORT_SYMBOL(set_user_nice);
......
......@@ -61,10 +61,12 @@ static inline runqueue_t *lock_task_rq(task_t *p, unsigned long *flags)
struct runqueue *__rq;
repeat_lock_task:
preempt_disable();
__rq = task_rq(p);
spin_lock_irqsave(&__rq->lock, *flags);
if (unlikely(__rq != task_rq(p))) {
spin_unlock_irqrestore(&__rq->lock, *flags);
preempt_enable();
goto repeat_lock_task;
}
return __rq;
......@@ -73,6 +75,7 @@ static inline runqueue_t *lock_task_rq(task_t *p, unsigned long *flags)
static inline void unlock_task_rq(runqueue_t *rq, unsigned long *flags)
{
spin_unlock_irqrestore(&rq->lock, *flags);
preempt_enable();
}
/*
* Adding/removing a task to/from a priority array:
......@@ -195,6 +198,7 @@ static inline void resched_task(task_t *p)
#ifdef CONFIG_SMP
int need_resched, nrpolling;
preempt_disable();
/* minimise the chance of sending an interrupt to poll_idle() */
nrpolling = test_tsk_thread_flag(p,TIF_POLLING_NRFLAG);
need_resched = test_and_set_tsk_thread_flag(p,TIF_NEED_RESCHED);
......@@ -202,6 +206,7 @@ static inline void resched_task(task_t *p)
if (!need_resched && !nrpolling && (p->thread_info->cpu != smp_processor_id()))
smp_send_reschedule(p->thread_info->cpu);
preempt_enable();
#else
set_tsk_need_resched(p);
#endif
......@@ -219,6 +224,7 @@ void wait_task_inactive(task_t * p)
runqueue_t *rq;
repeat:
preempt_disable();
rq = task_rq(p);
while (unlikely(rq->curr == p)) {
cpu_relax();
......@@ -227,9 +233,11 @@ void wait_task_inactive(task_t * p)
rq = lock_task_rq(p, &flags);
if (unlikely(rq->curr == p)) {
unlock_task_rq(rq, &flags);
preempt_enable();
goto repeat;
}
unlock_task_rq(rq, &flags);
preempt_enable();
}
/*
......@@ -295,7 +303,10 @@ int wake_up_process(task_t * p)
void wake_up_forked_process(task_t * p)
{
runqueue_t *rq = this_rq();
runqueue_t *rq;
preempt_disable();
rq = this_rq();
p->state = TASK_RUNNING;
if (!rt_task(p)) {
......@@ -308,6 +319,7 @@ void wake_up_forked_process(task_t * p)
p->thread_info->cpu = smp_processor_id();
activate_task(p, rq);
spin_unlock_irq(&rq->lock);
preempt_enable();
}
asmlinkage void schedule_tail(task_t *prev)
......@@ -635,17 +647,31 @@ void scheduling_functions_start_here(void) { }
*/
asmlinkage void schedule(void)
{
task_t *prev = current, *next;
runqueue_t *rq = this_rq();
task_t *prev, *next;
runqueue_t *rq;
prio_array_t *array;
list_t *queue;
int idx;
if (unlikely(in_interrupt()))
BUG();
preempt_disable();
prev = current;
rq = this_rq();
release_kernel_lock(prev, smp_processor_id());
spin_lock_irq(&rq->lock);
#ifdef CONFIG_PREEMPT
/*
* if entering from preempt_schedule, off a kernel preemption,
* go straight to picking the next task.
*/
if (unlikely(preempt_get_count() & PREEMPT_ACTIVE))
goto pick_next_task;
#endif
switch (prev->state) {
case TASK_RUNNING:
prev->sleep_timestamp = jiffies;
......@@ -659,7 +685,7 @@ asmlinkage void schedule(void)
default:
deactivate_task(prev, rq);
}
#if CONFIG_SMP
#if CONFIG_SMP || CONFIG_PREEMPT
pick_next_task:
#endif
if (unlikely(!rq->nr_running)) {
......@@ -707,9 +733,25 @@ asmlinkage void schedule(void)
spin_unlock_irq(&rq->lock);
reacquire_kernel_lock(current);
preempt_enable_no_resched();
return;
}
#ifdef CONFIG_PREEMPT
/*
* this is is the entry point to schedule() from in-kernel preemption.
*/
asmlinkage void preempt_schedule(void)
{
do {
current_thread_info()->preempt_count += PREEMPT_ACTIVE;
schedule();
current_thread_info()->preempt_count -= PREEMPT_ACTIVE;
barrier();
} while (test_thread_flag(TIF_NEED_RESCHED));
}
#endif /* CONFIG_PREEMPT */
/*
* The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
* wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
......@@ -1105,9 +1147,12 @@ asmlinkage long sys_sched_getparam(pid_t pid, struct sched_param *param)
asmlinkage long sys_sched_yield(void)
{
runqueue_t *rq = this_rq();
runqueue_t *rq;
prio_array_t *array;
preempt_disable();
rq = this_rq();
/*
* Decrease the yielding task's priority by one, to avoid
* livelocks. This priority loss is temporary, it's recovered
......@@ -1134,6 +1179,7 @@ asmlinkage long sys_sched_yield(void)
__set_bit(current->prio, array->bitmap);
}
spin_unlock(&rq->lock);
preempt_enable_no_resched();
schedule();
......
......@@ -132,7 +132,7 @@ static struct file_operations socket_file_ops = {
static struct net_proto_family *net_families[NPROTO];
#ifdef CONFIG_SMP
#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
static atomic_t net_family_lockct = ATOMIC_INIT(0);
static spinlock_t net_family_lock = SPIN_LOCK_UNLOCKED;
......
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