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Re: [PATCH/RFC] signal: Export signal_wake_up_state() to modules

From Oleg Nesterov <oleg@redhat.com>
Newsgroups linux.kernel
Subject Re: [PATCH/RFC] signal: Export signal_wake_up_state() to modules
Date 2017-05-06 21:50 +0200
Message-ID <tEdSh-3MB-13@gated-at.bofh.it> (permalink)
References <tDI26-8l5-13@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On 05/05, Geert Uytterhoeven wrote:
>
> I'm using signal_wake_up() to abort a task blocked on
> wait_for_completion_interruptible(), cfr. sh_msiof_slave_abort() in
> "spi: sh-msiof: Add slave mode support"
> (http://www.spinics.net/lists/devicetree/msg175575.html).
>
> Is exporting signal_wake_up_state() an acceptable solution?
> Alternatively, I can extract the code to abort an completion into a
> generic abort_completion() function, and export that.

I too do not think this is a good idea... signal_wake_up() or even
set_tsk_thread_flag() should never be used unless you actually send a
signal. Yes, freeze_task() does this too but note that recalc_sigpending()
checks freezing() and in this case we really want the target to enter the
get_signal() path.

And in fact I do not really understand why do you need it, it seems that
you can easily rework this code and avoid this hack.

Not to mention that sh_msiof_slave_abort() plays with struct completion
internals, this doesn't look good too.

Finally, clear_thread_flag(TIF_SIGPENDING) in sh_msiof_wait_for_completion()
looks wrong. Or it is only for kthreads?

Oleg.

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Thread

[PATCH/RFC] signal: Export signal_wake_up_state() to modules Geert Uytterhoeven <geert+renesas@glider.be> - 2017-05-05 11:50 +0200
  Re: [PATCH/RFC] signal: Export signal_wake_up_state() to modules Christoph Hellwig <hch@infradead.org> - 2017-05-05 12:10 +0200
    Re: [PATCH/RFC] signal: Export signal_wake_up_state() to modules Geert Uytterhoeven <geert@linux-m68k.org> - 2017-05-05 12:20 +0200
      Re: [PATCH/RFC] signal: Export signal_wake_up_state() to modules Geert Uytterhoeven <geert@linux-m68k.org> - 2017-05-05 13:10 +0200
        Re: [PATCH/RFC] signal: Export signal_wake_up_state() to modules Christoph Hellwig <hch@infradead.org> - 2017-05-05 13:30 +0200
          Re: [PATCH/RFC] signal: Export signal_wake_up_state() to modules Geert Uytterhoeven <geert@linux-m68k.org> - 2017-05-05 13:40 +0200
  Re: [PATCH/RFC] signal: Export signal_wake_up_state() to modules Oleg Nesterov <oleg@redhat.com> - 2017-05-06 21:50 +0200
    Re: [PATCH/RFC] signal: Export signal_wake_up_state() to modules Geert Uytterhoeven <geert@linux-m68k.org> - 2017-05-08 01:30 +0200

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