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* [PATCH 2/2] kernel/{exit.c, signal.c, power/process.c}: replace !likely(x) by likely(!x)
@ 2008-02-16 15:58 Roel Kluin
  2008-02-16 19:01 ` H. Peter Anvin
  0 siblings, 1 reply; 8+ messages in thread
From: Roel Kluin @ 2008-02-16 15:58 UTC (permalink / raw)
  To: hpa; +Cc: lkml

Not entirely sure who to send this to
---
Replace !likely(x) by likely(!x)

Signed-off-by: Roel Kluin <12o3l@tiscali.nl>
---
diff --git a/kernel/exit.c b/kernel/exit.c
index 506a957..df207fc 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1497,7 +1497,7 @@ repeat:
 				/*
 				 * We don't reap group leaders with subthreads.
 				 */
-				if (!likely(options & WEXITED))
+				if (likely(!(options & WEXITED)))
 					continue;
 				retval = wait_task_zombie(p,
 						(options & WNOWAIT), infop,
@@ -1508,7 +1508,7 @@ repeat:
 				 * exit, stop, or stop and then continue.
 				 */
 				flag = 1;
-				if (!unlikely(options & WCONTINUED))
+				if (unlikely(!(options & WCONTINUED)))
 					continue;
 				retval = wait_task_continued(p,
 						(options & WNOWAIT), infop,
diff --git a/kernel/power/process.c b/kernel/power/process.c
index 7c2118f..b42254b 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -36,7 +36,7 @@ static inline int freezeable(struct task_struct * p)
  */
 static inline void frozen_process(void)
 {
-	if (!unlikely(current->flags & PF_NOFREEZE)) {
+	if (unlikely(!(current->flags & PF_NOFREEZE))) {
 		current->flags |= PF_FROZEN;
 		wmb();
 	}
diff --git a/kernel/signal.c b/kernel/signal.c
index 84917fe..1155e16 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1308,7 +1308,7 @@ int send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
 	 */
 	rcu_read_lock();
 
-	if (!likely(lock_task_sighand(p, &flags))) {
+	if (likely(!lock_task_sighand(p, &flags))) {
 		ret = -1;
 		goto out_err;
 	}
@@ -1548,7 +1548,7 @@ static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
 
 static inline int may_ptrace_stop(void)
 {
-	if (!likely(current->ptrace & PT_PTRACED))
+	if (likely(!(current->ptrace & PT_PTRACED)))
 		return 0;
 	/*
 	 * Are we in the middle of do_coredump?
@@ -1574,7 +1574,7 @@ static int sigkill_pending(struct task_struct *tsk)
 {
 	return ((sigismember(&tsk->pending.signal, SIGKILL) ||
 		 sigismember(&tsk->signal->shared_pending.signal, SIGKILL)) &&
-		!unlikely(sigismember(&tsk->blocked, SIGKILL)));
+		 unlikely(!sigismember(&tsk->blocked, SIGKILL)));
 }
 
 /*
@@ -1625,7 +1625,7 @@ static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
 	spin_unlock_irq(&current->sighand->siglock);
 	try_to_freeze();
 	read_lock(&tasklist_lock);
-	if (!unlikely(killed) && may_ptrace_stop()) {
+	if (unlikely(!killed) && may_ptrace_stop()) {
 		do_notify_parent_cldstop(current, CLD_TRAPPED);
 		read_unlock(&tasklist_lock);
 		schedule();
@@ -1717,7 +1717,7 @@ static int do_signal_stop(int signr)
 	} else {
 		struct task_struct *t;
 
-		if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
+		if (likely(!(sig->flags & SIGNAL_STOP_DEQUEUED)) ||
 		    unlikely(sig->group_exit_task))
 			return 0;
 		/*


^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH 2/2] kernel/{exit.c, signal.c, power/process.c}: replace !likely(x) by likely(!x)
  2008-02-16 15:58 [PATCH 2/2] kernel/{exit.c, signal.c, power/process.c}: replace !likely(x) by likely(!x) Roel Kluin
@ 2008-02-16 19:01 ` H. Peter Anvin
  2008-02-16 19:29   ` Roel Kluin
  2008-02-17  2:33   ` Rene Herman
  0 siblings, 2 replies; 8+ messages in thread
From: H. Peter Anvin @ 2008-02-16 19:01 UTC (permalink / raw)
  To: Roel Kluin; +Cc: lkml

Roel Kluin wrote:
> Not entirely sure who to send this to
> ---
> Replace !likely(x) by likely(!x)

Whoa...

Are you sure this is correct?

!likely(x) is equivalent to unlikely(!x), not the opposite, so this is a 
functional change...

	-hpa

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH 2/2] kernel/{exit.c, signal.c, power/process.c}: replace !likely(x) by likely(!x)
  2008-02-16 19:01 ` H. Peter Anvin
@ 2008-02-16 19:29   ` Roel Kluin
  2008-02-16 19:31     ` H. Peter Anvin
  2008-02-17  2:33   ` Rene Herman
  1 sibling, 1 reply; 8+ messages in thread
From: Roel Kluin @ 2008-02-16 19:29 UTC (permalink / raw)
  To: H. Peter Anvin; +Cc: lkml

H. Peter Anvin wrote:
> Roel Kluin wrote:
>> Not entirely sure who to send this to
>> ---
>> Replace !likely(x) by likely(!x)
> 
> Whoa...
> 
> Are you sure this is correct?
> 
> !likely(x) is equivalent to unlikely(!x), not the opposite, so this is a
> functional change...
> 
>     -hpa
> 
You are right, sorry, Need more caffeine. I will send the right patch later.

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH 2/2] kernel/{exit.c, signal.c, power/process.c}: replace !likely(x) by likely(!x)
  2008-02-16 19:29   ` Roel Kluin
@ 2008-02-16 19:31     ` H. Peter Anvin
  2008-02-16 19:52       ` Roel Kluin
  0 siblings, 1 reply; 8+ messages in thread
From: H. Peter Anvin @ 2008-02-16 19:31 UTC (permalink / raw)
  To: Roel Kluin; +Cc: lkml

Roel Kluin wrote:
> H. Peter Anvin wrote:
>> Roel Kluin wrote:
>>> Not entirely sure who to send this to
>>> ---
>>> Replace !likely(x) by likely(!x)
>> Whoa...
>>
>> Are you sure this is correct?
>>
>> !likely(x) is equivalent to unlikely(!x), not the opposite, so this is a
>> functional change...
>>
> You are right, sorry, Need more caffeine. I will send the right patch later.

Note I didn't say it was wrong, I just wanted a bit more explanation 
about why it's right, if it is.

	-hpa

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH 2/2] kernel/{exit.c, signal.c, power/process.c}: replace !likely(x) by likely(!x)
  2008-02-16 19:31     ` H. Peter Anvin
@ 2008-02-16 19:52       ` Roel Kluin
  0 siblings, 0 replies; 8+ messages in thread
From: Roel Kluin @ 2008-02-16 19:52 UTC (permalink / raw)
  To: H. Peter Anvin; +Cc: lkml

H. Peter Anvin wrote:
> Roel Kluin wrote:
>> H. Peter Anvin wrote:
>>> Roel Kluin wrote:
>>>> Not entirely sure who to send this to
>>>> ---
>>>> Replace !likely(x) by likely(!x)
>>> Whoa...
>>>
>>> Are you sure this is correct?
>>>
>>> !likely(x) is equivalent to unlikely(!x), not the opposite, so this is a
>>> functional change...
>>>
>> You are right, sorry, Need more caffeine. I will send the right patch
>> later.
> 
> Note I didn't say it was wrong, I just wanted a bit more explanation
> about why it's right, if it is.

No, I just wanted to move the '!' within the parentheses, I didn't want
to change semantics. below is how I guess the patch should have been. 
Thanks for your response.
---
Replace !likely(x) by unlikely(!x)

Signed-off-by: Roel Kluin <12o3l@tiscali.nl>
---
diff --git a/kernel/signal.c b/kernel/signal.c
index 84917fe..cf5d45a 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1308,7 +1308,7 @@ int send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
 	 */
 	rcu_read_lock();
 
-	if (!likely(lock_task_sighand(p, &flags))) {
+	if (unlikely(!lock_task_sighand(p, &flags))) {
 		ret = -1;
 		goto out_err;
 	}
@@ -1548,7 +1548,7 @@ static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
 
 static inline int may_ptrace_stop(void)
 {
-	if (!likely(current->ptrace & PT_PTRACED))
+	if (unlikely(!(current->ptrace & PT_PTRACED)))
 		return 0;
 	/*
 	 * Are we in the middle of do_coredump?
@@ -1574,7 +1574,7 @@ static int sigkill_pending(struct task_struct *tsk)
 {
 	return ((sigismember(&tsk->pending.signal, SIGKILL) ||
 		 sigismember(&tsk->signal->shared_pending.signal, SIGKILL)) &&
-		!unlikely(sigismember(&tsk->blocked, SIGKILL)));
+		 likely(!sigismember(&tsk->blocked, SIGKILL)));
 }
 
 /*
@@ -1625,7 +1625,7 @@ static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
 	spin_unlock_irq(&current->sighand->siglock);
 	try_to_freeze();
 	read_lock(&tasklist_lock);
-	if (!unlikely(killed) && may_ptrace_stop()) {
+	if (likely(!killed) && may_ptrace_stop()) {
 		do_notify_parent_cldstop(current, CLD_TRAPPED);
 		read_unlock(&tasklist_lock);
 		schedule();
@@ -1717,8 +1717,8 @@ static int do_signal_stop(int signr)
 	} else {
 		struct task_struct *t;
 
-		if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
-		    unlikely(sig->group_exit_task))
+		if (unlikely(!(sig->flags & SIGNAL_STOP_DEQUEUED) ||
+		    sig->group_exit_task))
 			return 0;
 		/*
 		 * There is no group stop already in progress.


^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH 2/2] kernel/{exit.c, signal.c, power/process.c}: replace !likely(x) by likely(!x)
  2008-02-16 19:01 ` H. Peter Anvin
  2008-02-16 19:29   ` Roel Kluin
@ 2008-02-17  2:33   ` Rene Herman
  2008-02-17  3:56     ` H. Peter Anvin
  1 sibling, 1 reply; 8+ messages in thread
From: Rene Herman @ 2008-02-17  2:33 UTC (permalink / raw)
  To: H. Peter Anvin; +Cc: Roel Kluin, lkml

On 16-02-08 20:01, H. Peter Anvin wrote:
> Roel Kluin wrote:
>> Not entirely sure who to send this to
>> ---
>> Replace !likely(x) by likely(!x)
> 
> Whoa...
> 
> Are you sure this is correct?
> 
> !likely(x) is equivalent to unlikely(!x)

Not with respect to its value I believe? likely(x) == !!(x), and 
unlikely(!x) == !!(!x) = !x, so conditions work out differently?

> not the opposite, so this is a functional change...

Rene.

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH 2/2] kernel/{exit.c, signal.c, power/process.c}: replace !likely(x) by likely(!x)
  2008-02-17  2:33   ` Rene Herman
@ 2008-02-17  3:56     ` H. Peter Anvin
  2008-02-17  4:16       ` Rene Herman
  0 siblings, 1 reply; 8+ messages in thread
From: H. Peter Anvin @ 2008-02-17  3:56 UTC (permalink / raw)
  To: Rene Herman; +Cc: Roel Kluin, lkml

Rene Herman wrote:
> On 16-02-08 20:01, H. Peter Anvin wrote:
>> Roel Kluin wrote:
>>> Not entirely sure who to send this to
>>> ---
>>> Replace !likely(x) by likely(!x)
>>
>> Whoa...
>>
>> Are you sure this is correct?
>>
>> !likely(x) is equivalent to unlikely(!x)
> 
> Not with respect to its value I believe? likely(x) == !!(x), and 
> unlikely(!x) == !!(!x) = !x, so conditions work out differently?

You missed one ! sign:

!likely(x) == !!!(x) == unlikely(!x) == !!(!(x))

	-hpa

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH 2/2] kernel/{exit.c, signal.c, power/process.c}: replace !likely(x) by likely(!x)
  2008-02-17  3:56     ` H. Peter Anvin
@ 2008-02-17  4:16       ` Rene Herman
  0 siblings, 0 replies; 8+ messages in thread
From: Rene Herman @ 2008-02-17  4:16 UTC (permalink / raw)
  To: H. Peter Anvin; +Cc: Roel Kluin, lkml

On 17-02-08 04:56, H. Peter Anvin wrote:

> Rene Herman wrote:
>> On 16-02-08 20:01, H. Peter Anvin wrote:
>>> Roel Kluin wrote:
>>>> Not entirely sure who to send this to
>>>> ---
>>>> Replace !likely(x) by likely(!x)
>>>
>>> Whoa...
>>>
>>> Are you sure this is correct?
>>>
>>> !likely(x) is equivalent to unlikely(!x)
>>
>> Not with respect to its value I believe? likely(x) == !!(x), and 
>> unlikely(!x) == !!(!x) = !x, so conditions work out differently?
> 
> You missed one ! sign:
> 
> !likely(x) == !!!(x) == unlikely(!x) == !!(!(x))

Yup, sorry, misread.

Rene.

^ permalink raw reply	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2008-02-17  4:14 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2008-02-16 15:58 [PATCH 2/2] kernel/{exit.c, signal.c, power/process.c}: replace !likely(x) by likely(!x) Roel Kluin
2008-02-16 19:01 ` H. Peter Anvin
2008-02-16 19:29   ` Roel Kluin
2008-02-16 19:31     ` H. Peter Anvin
2008-02-16 19:52       ` Roel Kluin
2008-02-17  2:33   ` Rene Herman
2008-02-17  3:56     ` H. Peter Anvin
2008-02-17  4:16       ` Rene Herman

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