[PATCH] Software suspend and recalc sigpending bug fix

[PATCH] Software suspend and recalc sigpending bug fix

[Kirill Korotaev]

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This patch fixes recalc_sigpending() to work correctly
with tasks which are being freezed. The problem is that
freeze_processes() sets PF_FREEZE and TIF_SIGPENDING
flags on tasks, but recalc_sigpending() called from
e.g. sys_rt_sigtimedwait or any other kernel place
will clear TIF_SIGPENDING due to no pending signals queued
and the tasks won't be freezed until it recieves a real signal
or freezed_processes() fail due to timeout.

Signed-Off-By: Kirill Korotaev <dev@sw.ru>
Signed-Off-By: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>

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--- ./kernel/signal.c.freezesigrec	2005-05-10 16:10:40.000000000 +0400
+++ ./kernel/signal.c	2005-05-10 18:10:08.000000000 +0400
@@ -212,6 +212,7 @@ static inline int has_pending_signals(si
 fastcall void recalc_sigpending_tsk(struct task_struct *t)
 {
 	if (t->signal->group_stop_count > 0 ||
+	    (t->flags&PF_FREEZE) ||
 	    PENDING(&t->pending, &t->blocked) ||
 	    PENDING(&t->signal->shared_pending, &t->blocked))
 		set_tsk_thread_flag(t, TIF_SIGPENDING);

Re: [PATCH] Software suspend and recalc sigpending bug fix

[Pavel Machek]

On St 11-05-05 19:20:47, Kirill Korotaev wrote:
> This patch fixes recalc_sigpending() to work correctly
> with tasks which are being freezed. The problem is that
> freeze_processes() sets PF_FREEZE and TIF_SIGPENDING
> flags on tasks, but recalc_sigpending() called from
> e.g. sys_rt_sigtimedwait or any other kernel place
> will clear TIF_SIGPENDING due to no pending signals queued
> and the tasks won't be freezed until it recieves a real signal
> or freezed_processes() fail due to timeout.
> 
> Signed-Off-By: Kirill Korotaev <dev@sw.ru>
> Signed-Off-By: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>

This should fix our problems with mysqld, right? Yes, patch looks good
(modulo missing whitespace around &)). I'll apply it to my tree. (Or
andrew, if you prefer, just take it...
								Pavel

> --- ./kernel/signal.c.freezesigrec	2005-05-10 16:10:40.000000000 +0400
> +++ ./kernel/signal.c	2005-05-10 18:10:08.000000000 +0400
> @@ -212,6 +212,7 @@ static inline int has_pending_signals(si
>  fastcall void recalc_sigpending_tsk(struct task_struct *t)
>  {
>  	if (t->signal->group_stop_count > 0 ||
> +	    (t->flags&PF_FREEZE) ||
>  	    PENDING(&t->pending, &t->blocked) ||
>  	    PENDING(&t->signal->shared_pending, &t->blocked))
>  		set_tsk_thread_flag(t, TIF_SIGPENDING);


-- 
Boycott Kodak -- for their patent abuse against Java.

Re: [PATCH] Software suspend and recalc sigpending bug fix

[Kirill Korotaev]

>>This patch fixes recalc_sigpending() to work correctly
>>with tasks which are being freezed. The problem is that
>>freeze_processes() sets PF_FREEZE and TIF_SIGPENDING
>>flags on tasks, but recalc_sigpending() called from
>>e.g. sys_rt_sigtimedwait or any other kernel place
>>will clear TIF_SIGPENDING due to no pending signals queued
>>and the tasks won't be freezed until it recieves a real signal
>>or freezed_processes() fail due to timeout.
>>
>>Signed-Off-By: Kirill Korotaev <dev@sw.ru>
>>Signed-Off-By: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
> 
> 
> This should fix our problems with mysqld, right? Yes, patch looks good
> (modulo missing whitespace around &)). I'll apply it to my tree. (Or
> andrew, if you prefer, just take it...

Another cleanup idea in swsusp: it would be nice if all such checks for 
PF_FREEZE were wrapped in inline function 
is_task_freezing()/any_thing_else, to make freeze code disappear when 
CONFIG_PM/CONFIG_SOFTWARE_SUSPEND is off...

Kirill

> 								Pavel
> 
> 
>>--- ./kernel/signal.c.freezesigrec	2005-05-10 16:10:40.000000000 +0400
>>+++ ./kernel/signal.c	2005-05-10 18:10:08.000000000 +0400
>>@@ -212,6 +212,7 @@ static inline int has_pending_signals(si
>> fastcall void recalc_sigpending_tsk(struct task_struct *t)
>> {
>> 	if (t->signal->group_stop_count > 0 ||
>>+	    (t->flags&PF_FREEZE) ||
>> 	    PENDING(&t->pending, &t->blocked) ||
>> 	    PENDING(&t->signal->shared_pending, &t->blocked))
>> 		set_tsk_thread_flag(t, TIF_SIGPENDING);
> 
> 
> 

Re: [PATCH] Software suspend and recalc sigpending bug fix

[Pavel Machek]

On Čt 12-05-05 10:43:51, Kirill Korotaev wrote:
> >>This patch fixes recalc_sigpending() to work correctly
> >>with tasks which are being freezed. The problem is that
> >>freeze_processes() sets PF_FREEZE and TIF_SIGPENDING
> >>flags on tasks, but recalc_sigpending() called from
> >>e.g. sys_rt_sigtimedwait or any other kernel place
> >>will clear TIF_SIGPENDING due to no pending signals queued
> >>and the tasks won't be freezed until it recieves a real signal
> >>or freezed_processes() fail due to timeout.
> >>
> >>Signed-Off-By: Kirill Korotaev <dev@sw.ru>
> >>Signed-Off-By: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
> >
> >
> >This should fix our problems with mysqld, right? Yes, patch looks good
> >(modulo missing whitespace around &)). I'll apply it to my tree. (Or
> >andrew, if you prefer, just take it...
> 
> Another cleanup idea in swsusp: it would be nice if all such checks for 
> PF_FREEZE were wrapped in inline function 
> is_task_freezing()/any_thing_else, to make freeze code disappear when 
> CONFIG_PM/CONFIG_SOFTWARE_SUSPEND is off...

S3 case needs this, too. Nicer solution would be to just define
PF_FREEZE to 0 when it is not needed; but as most hooks are hidden in
try_to_freeze(), anyway, I do not think this is worth it.
								Pavel
-- 
Boycott Kodak -- for their patent abuse against Java.