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

Pull rseq updates from Ingo Molnar:
 "A cleanup and a fix to comments"

* 'core-rseq-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rseq: Remove superfluous rseq_len from task_struct
  rseq: Clean up comments by reflecting removal of event counter

arch/arm/kernel/signal.c

@@ -549,8 +549,7 @@ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 	int ret;
 
 	/*
-	 * Increment event counter and perform fixup for the pre-signal
-	 * frame.
+	 * Perform fixup for the pre-signal frame.
 	 */
 	rseq_signal_deliver(ksig, regs);
 

arch/x86/kernel/signal.c

@@ -693,10 +693,7 @@ setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
 	sigset_t *set = sigmask_to_save();
 	compat_sigset_t *cset = (compat_sigset_t *) set;
 
-	/*
-	 * Increment event counter and perform fixup for the pre-signal
-	 * frame.
-	 */
+	/* Perform fixup for the pre-signal frame. */
 	rseq_signal_deliver(ksig, regs);
 
 	/* Set up the stack frame */

include/linux/sched.h

@@ -1057,7 +1057,6 @@ struct task_struct {
 
 #ifdef CONFIG_RSEQ
 	struct rseq __user *rseq;
-	u32 rseq_len;
 	u32 rseq_sig;
 	/*
 	 * RmW on rseq_event_mask must be performed atomically
@@ -1855,12 +1854,10 @@ static inline void rseq_fork(struct task_struct *t, unsigned long clone_flags)
 {
 	if (clone_flags & CLONE_THREAD) {
 		t->rseq = NULL;
-		t->rseq_len = 0;
 		t->rseq_sig = 0;
 		t->rseq_event_mask = 0;
 	} else {
 		t->rseq = current->rseq;
-		t->rseq_len = current->rseq_len;
 		t->rseq_sig = current->rseq_sig;
 		t->rseq_event_mask = current->rseq_event_mask;
 	}
@@ -1869,7 +1866,6 @@ static inline void rseq_fork(struct task_struct *t, unsigned long clone_flags)
 static inline void rseq_execve(struct task_struct *t)
 {
 	t->rseq = NULL;
-	t->rseq_len = 0;
 	t->rseq_sig = 0;
 	t->rseq_event_mask = 0;
 }

kernel/rseq.c

@@ -254,8 +254,7 @@ static int rseq_ip_fixup(struct pt_regs *regs)
  * - signal delivery,
  * and return to user-space.
  *
- * This is how we can ensure that the entire rseq critical section,
- * consisting of both the C part and the assembly instruction sequence,
+ * This is how we can ensure that the entire rseq critical section
  * will issue the commit instruction only if executed atomically with
  * respect to other threads scheduled on the same CPU, and with respect
  * to signal handlers.
@@ -314,7 +313,7 @@ SYSCALL_DEFINE4(rseq, struct rseq __user *, rseq, u32, rseq_len,
 		/* Unregister rseq for current thread. */
 		if (current->rseq != rseq || !current->rseq)
 			return -EINVAL;
-		if (current->rseq_len != rseq_len)
+		if (rseq_len != sizeof(*rseq))
 			return -EINVAL;
 		if (current->rseq_sig != sig)
 			return -EPERM;
@@ -322,7 +321,6 @@ SYSCALL_DEFINE4(rseq, struct rseq __user *, rseq, u32, rseq_len,
 		if (ret)
 			return ret;
 		current->rseq = NULL;
-		current->rseq_len = 0;
 		current->rseq_sig = 0;
 		return 0;
 	}
@@ -336,7 +334,7 @@ SYSCALL_DEFINE4(rseq, struct rseq __user *, rseq, u32, rseq_len,
 		 * the provided address differs from the prior
 		 * one.
 		 */
-		if (current->rseq != rseq || current->rseq_len != rseq_len)
+		if (current->rseq != rseq || rseq_len != sizeof(*rseq))
 			return -EINVAL;
 		if (current->rseq_sig != sig)
 			return -EPERM;
@@ -354,7 +352,6 @@ SYSCALL_DEFINE4(rseq, struct rseq __user *, rseq, u32, rseq_len,
 	if (!access_ok(rseq, rseq_len))
 		return -EFAULT;
 	current->rseq = rseq;
-	current->rseq_len = rseq_len;
 	current->rseq_sig = sig;
 	/*
 	 * If rseq was previously inactive, and has just been