* [PATCH -mm 6/6] cpu_relax(): ptrace.c coding style fix
@ 2006-06-21 21:00 Andreas Mohr
2006-06-22 14:32 ` Nathan Lynch
2006-06-22 15:08 ` Pavel Machek
0 siblings, 2 replies; 4+ messages in thread
From: Andreas Mohr @ 2006-06-21 21:00 UTC (permalink / raw)
To: Andrew Morton; +Cc: linux-kernel
Fix existing cpu_relax() loop to have proper kernel style.
Tested on 2.6.17-mm1.
Signed-off-by: Andreas Mohr <andi@lisas.de>
diff -urN linux-2.6.17-mm1.orig/kernel/ptrace.c linux-2.6.17-mm1.my/kernel/ptrace.c
--- linux-2.6.17-mm1.orig/kernel/ptrace.c 2006-06-21 14:28:20.000000000 +0200
+++ linux-2.6.17-mm1.my/kernel/ptrace.c 2006-06-21 14:43:24.000000000 +0200
@@ -182,9 +182,8 @@
if (!write_trylock(&tasklist_lock)) {
local_irq_enable();
task_unlock(task);
- do {
+ while (!write_can_lock(&tasklist_lock))
cpu_relax();
- } while (!write_can_lock(&tasklist_lock));
goto repeat;
}
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH -mm 6/6] cpu_relax(): ptrace.c coding style fix
2006-06-21 21:00 [PATCH -mm 6/6] cpu_relax(): ptrace.c coding style fix Andreas Mohr
@ 2006-06-22 14:32 ` Nathan Lynch
2006-06-22 15:53 ` Andreas Mohr
2006-06-22 15:08 ` Pavel Machek
1 sibling, 1 reply; 4+ messages in thread
From: Nathan Lynch @ 2006-06-22 14:32 UTC (permalink / raw)
To: Andreas Mohr; +Cc: Andrew Morton, linux-kernel
Andreas Mohr wrote:
>
> Fix existing cpu_relax() loop to have proper kernel style.
>
...
> @@ -182,9 +182,8 @@
> if (!write_trylock(&tasklist_lock)) {
> local_irq_enable();
> task_unlock(task);
> - do {
> + while (!write_can_lock(&tasklist_lock))
> cpu_relax();
> - } while (!write_can_lock(&tasklist_lock));
This is a change in behavior, not just style. (And there is nothing
wrong with the current style.)
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH -mm 6/6] cpu_relax(): ptrace.c coding style fix
2006-06-22 14:32 ` Nathan Lynch
@ 2006-06-22 15:53 ` Andreas Mohr
0 siblings, 0 replies; 4+ messages in thread
From: Andreas Mohr @ 2006-06-22 15:53 UTC (permalink / raw)
To: Nathan Lynch; +Cc: Andrew Morton, linux-kernel
On Thu, Jun 22, 2006 at 09:32:23AM -0500, Nathan Lynch wrote:
> Andreas Mohr wrote:
> >
> > Fix existing cpu_relax() loop to have proper kernel style.
> >
>
> ...
>
> > @@ -182,9 +182,8 @@
> > if (!write_trylock(&tasklist_lock)) {
> > local_irq_enable();
> > task_unlock(task);
> > - do {
> > + while (!write_can_lock(&tasklist_lock))
> > cpu_relax();
> > - } while (!write_can_lock(&tasklist_lock));
>
> This is a change in behavior, not just style. (And there is nothing
> wrong with the current style.)
Ick, right, this could cause the new state to be visible in the 2nd iteration
only.
Thanks! Discard this change please.
Andreas Mohr
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH -mm 6/6] cpu_relax(): ptrace.c coding style fix
2006-06-21 21:00 [PATCH -mm 6/6] cpu_relax(): ptrace.c coding style fix Andreas Mohr
2006-06-22 14:32 ` Nathan Lynch
@ 2006-06-22 15:08 ` Pavel Machek
1 sibling, 0 replies; 4+ messages in thread
From: Pavel Machek @ 2006-06-22 15:08 UTC (permalink / raw)
To: Andreas Mohr; +Cc: Andrew Morton, linux-kernel
Hi!
> Fix existing cpu_relax() loop to have proper kernel style.
..but you change the code, not its style.
> @@ -182,9 +182,8 @@
> if (!write_trylock(&tasklist_lock)) {
> local_irq_enable();
> task_unlock(task);
> - do {
> + while (!write_can_lock(&tasklist_lock))
> cpu_relax();
> - } while (!write_can_lock(&tasklist_lock));
> goto repeat;
> }
I guess that barrier was needed before write_can_lock can succeed.
=> your version does one unneccessary test.
--
64 bytes from 195.113.31.123: icmp_seq=28 ttl=51 time=448769.1 ms
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2006-06-22 19:05 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2006-06-21 21:00 [PATCH -mm 6/6] cpu_relax(): ptrace.c coding style fix Andreas Mohr
2006-06-22 14:32 ` Nathan Lynch
2006-06-22 15:53 ` Andreas Mohr
2006-06-22 15:08 ` Pavel Machek
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