Messages in this thread | | | Date | Tue, 30 Apr 2013 18:38:17 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 09/10] sigtimedwait: use freezable blocking call |
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On 04/29, Colin Cross wrote: > > Avoid waking up every thread sleeping in a sigtimedwait call during > suspend and resume by calling a freezable blocking call.
This doesn't explain why do want this change...
OK, probably to avoid -EAGAIN from sigtimedwait() if the freezer wakes up the caller.
> --- a/kernel/signal.c > +++ b/kernel/signal.c > @@ -2845,7 +2845,7 @@ int do_sigtimedwait(const sigset_t *which, siginfo_t *info, > recalc_sigpending(); > spin_unlock_irq(&tsk->sighand->siglock); > > - timeout = schedule_timeout_interruptible(timeout); > + timeout = freezable_schedule_timeout_interruptible(timeout);
And I guess freezable_schedule_timeout_interruptible() is added by http://marc.info/?l=linux-kernel&m=136727195719575 ...
+#define freezable_schedule_timeout_interruptible(timeout) \ +({ \ + long __retval; \ + freezer_do_not_count(); \ + __retval = schedule_timeout_interruptible(timeout); \ + freezer_count(); \ + __retval; \ +})
How this can help?
The task will be interrupted anyway and the syscall will return -EAGAIN, this only changes the time when try_to_freeze() is called.
For what? The task will call do_signal/try_to_freeze really "soon".
Confused...
Oleg.
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