Re: [PATCH 3/3] signal: do_sigtimedwait() needsretarget_shared_pending()

From: Matt Fleming
Date: Tue Apr 26 2011 - 06:42:58 EST


On Sat, 23 Apr 2011 20:00:00 +0200
Oleg Nesterov <oleg@xxxxxxxxxx> wrote:

> do_sigtimedwait() changes current->blocked and thus it needs
> set_current_bloked()->retarget_shared_pending().

If you do another version of this patch could you fix up the function
names in the commit log, s/set_current_bloked/set_current_blocked/ ? Or
maybe Andrew can fix it up if he pulls them into -mm.

> We could use set_current_bloked() directly. It is fine to change
> ->real_blocked from all-zeroes to ->blocked and vice versa lockless,
> but this is not immediately clear, looks racy, and needs a huge
> comment to explain why this is correct.
>
> To keep the things simple this patch adds the new static helper,
> __set_task_blocked() which should be called with ->siglock held. This
> way we can change both ->real_blocked and ->blocked atomically under
> ->siglock as the current code does. This is more understandable.
>
> Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>

Reviewed-by: Matt Fleming <matt.fleming@xxxxxxxxxxxxxxx>

--
Matt Fleming, Intel Open Source Technology Center
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