* [PATCH/RFC] signal: Export signal_wake_up_state() to modules
@ 2017-05-05 9:49 Geert Uytterhoeven
2017-05-05 10:07 ` Christoph Hellwig
2017-05-06 19:42 ` Oleg Nesterov
0 siblings, 2 replies; 8+ messages in thread
From: Geert Uytterhoeven @ 2017-05-05 9:49 UTC (permalink / raw)
To: Ingo Molnar, Peter Zijlstra, Oleg Nesterov, Thomas Gleixner
Cc: linux-kernel, linux-spi, Geert Uytterhoeven
When using signal_wake_up() from a loadable kernel module:
ERROR: "signal_wake_up_state" [drivers/spi/spi-sh-msiof.ko] undefined!
Export signal_wake_up_state() to modules to fix this.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
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.
Or is there a better way to abort a completion?
Thanks!
---
kernel/signal.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/signal.c b/kernel/signal.c
index 7e59ebc2c25e669e..f130598acd34f08b 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -660,6 +660,7 @@ void signal_wake_up_state(struct task_struct *t, unsigned int state)
if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
kick_process(t);
}
+EXPORT_SYMBOL_GPL(signal_wake_up_state);
/*
* Remove signals in mask from the pending set and queue.
--
2.7.4
^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH/RFC] signal: Export signal_wake_up_state() to modules
2017-05-05 9:49 [PATCH/RFC] signal: Export signal_wake_up_state() to modules Geert Uytterhoeven
@ 2017-05-05 10:07 ` Christoph Hellwig
2017-05-05 10:13 ` Geert Uytterhoeven
2017-05-06 19:42 ` Oleg Nesterov
1 sibling, 1 reply; 8+ messages in thread
From: Christoph Hellwig @ 2017-05-05 10:07 UTC (permalink / raw)
To: Geert Uytterhoeven
Cc: Ingo Molnar, Peter Zijlstra, Oleg Nesterov, Thomas Gleixner,
linux-kernel, linux-spi
On Fri, May 05, 2017 at 11:49:11AM +0200, Geert Uytterhoeven wrote:
> When using signal_wake_up() from a loadable kernel module:
>
> ERROR: "signal_wake_up_state" [drivers/spi/spi-sh-msiof.ko] undefined!
>
> Export signal_wake_up_state() to modules to fix this.
Or rever the commit that added the users. This doesn't look like
functionality a driver should use..
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH/RFC] signal: Export signal_wake_up_state() to modules
2017-05-05 10:07 ` Christoph Hellwig
@ 2017-05-05 10:13 ` Geert Uytterhoeven
2017-05-05 11:08 ` Geert Uytterhoeven
0 siblings, 1 reply; 8+ messages in thread
From: Geert Uytterhoeven @ 2017-05-05 10:13 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Geert Uytterhoeven, Ingo Molnar, Peter Zijlstra, Oleg Nesterov,
Thomas Gleixner, linux-kernel, linux-spi
Hi Christoph,
On Fri, May 5, 2017 at 12:07 PM, Christoph Hellwig <hch@infradead.org> wrote:
> On Fri, May 05, 2017 at 11:49:11AM +0200, Geert Uytterhoeven wrote:
>> When using signal_wake_up() from a loadable kernel module:
>>
>> ERROR: "signal_wake_up_state" [drivers/spi/spi-sh-msiof.ko] undefined!
>>
>> Export signal_wake_up_state() to modules to fix this.
>
> Or rever the commit that added the users. This doesn't look like
That commit is not yet applied.
> functionality a driver should use..
OK.
Then, do you have any advise on how to properly abort a completion?
Thanks!
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH/RFC] signal: Export signal_wake_up_state() to modules
2017-05-05 10:13 ` Geert Uytterhoeven
@ 2017-05-05 11:08 ` Geert Uytterhoeven
2017-05-05 11:22 ` Christoph Hellwig
0 siblings, 1 reply; 8+ messages in thread
From: Geert Uytterhoeven @ 2017-05-05 11:08 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Geert Uytterhoeven, Ingo Molnar, Peter Zijlstra, Oleg Nesterov,
Thomas Gleixner, linux-kernel, linux-spi
On Fri, May 5, 2017 at 12:13 PM, Geert Uytterhoeven
<geert@linux-m68k.org> wrote:
> On Fri, May 5, 2017 at 12:07 PM, Christoph Hellwig <hch@infradead.org> wrote:
>> On Fri, May 05, 2017 at 11:49:11AM +0200, Geert Uytterhoeven wrote:
>>> When using signal_wake_up() from a loadable kernel module:
>>>
>>> ERROR: "signal_wake_up_state" [drivers/spi/spi-sh-msiof.ko] undefined!
>>>
>>> Export signal_wake_up_state() to modules to fix this.
>>
>> Or rever the commit that added the users. This doesn't look like
>
> That commit is not yet applied.
>
>> functionality a driver should use..
>
> OK.
>
> Then, do you have any advise on how to properly abort a completion?
Of course I can add a flag to indicate abortion, and just call complete_all(),
but IMHO that's a bit silly, given wait_for_completion_interruptible() already
provides this side channel information through -ERESTARTSYS.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH/RFC] signal: Export signal_wake_up_state() to modules
2017-05-05 11:08 ` Geert Uytterhoeven
@ 2017-05-05 11:22 ` Christoph Hellwig
2017-05-05 11:35 ` Geert Uytterhoeven
0 siblings, 1 reply; 8+ messages in thread
From: Christoph Hellwig @ 2017-05-05 11:22 UTC (permalink / raw)
To: Geert Uytterhoeven
Cc: Christoph Hellwig, Geert Uytterhoeven, Ingo Molnar,
Peter Zijlstra, Oleg Nesterov, Thomas Gleixner, linux-kernel,
linux-spi
On Fri, May 05, 2017 at 01:08:47PM +0200, Geert Uytterhoeven wrote:
> Of course I can add a flag to indicate abortion, and just call complete_all(),
> but IMHO that's a bit silly, given wait_for_completion_interruptible() already
> provides this side channel information through -ERESTARTSYS.
Even if this was the right channel (which I'm not sure about) it
should be provided as an abstract API operating on the completion.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH/RFC] signal: Export signal_wake_up_state() to modules
2017-05-05 11:22 ` Christoph Hellwig
@ 2017-05-05 11:35 ` Geert Uytterhoeven
0 siblings, 0 replies; 8+ messages in thread
From: Geert Uytterhoeven @ 2017-05-05 11:35 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Geert Uytterhoeven, Ingo Molnar, Peter Zijlstra, Oleg Nesterov,
Thomas Gleixner, linux-kernel, linux-spi
Hi Christoph,
On Fri, May 5, 2017 at 1:22 PM, Christoph Hellwig <hch@infradead.org> wrote:
> On Fri, May 05, 2017 at 01:08:47PM +0200, Geert Uytterhoeven wrote:
>> Of course I can add a flag to indicate abortion, and just call complete_all(),
>> but IMHO that's a bit silly, given wait_for_completion_interruptible() already
>> provides this side channel information through -ERESTARTSYS.
>
> Even if this was the right channel (which I'm not sure about) it
> should be provided as an abstract API operating on the completion.
Hence my other question in the patch comments:
| 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.
Thanks!
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH/RFC] signal: Export signal_wake_up_state() to modules
2017-05-05 9:49 [PATCH/RFC] signal: Export signal_wake_up_state() to modules Geert Uytterhoeven
2017-05-05 10:07 ` Christoph Hellwig
@ 2017-05-06 19:42 ` Oleg Nesterov
2017-05-07 9:47 ` Geert Uytterhoeven
1 sibling, 1 reply; 8+ messages in thread
From: Oleg Nesterov @ 2017-05-06 19:42 UTC (permalink / raw)
To: Geert Uytterhoeven
Cc: Ingo Molnar, Peter Zijlstra, Thomas Gleixner, linux-kernel, linux-spi
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.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH/RFC] signal: Export signal_wake_up_state() to modules
2017-05-06 19:42 ` Oleg Nesterov
@ 2017-05-07 9:47 ` Geert Uytterhoeven
0 siblings, 0 replies; 8+ messages in thread
From: Geert Uytterhoeven @ 2017-05-07 9:47 UTC (permalink / raw)
To: Oleg Nesterov
Cc: Geert Uytterhoeven, Ingo Molnar, Peter Zijlstra, Thomas Gleixner,
linux-kernel, linux-spi
Hi Oleg,
On Sat, May 6, 2017 at 9:42 PM, Oleg Nesterov <oleg@redhat.com> wrote:
> 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.
You mean having my own aborted flag, and calling complete_all()?
> Not to mention that sh_msiof_slave_abort() plays with struct completion
> internals, this doesn't look good too.
One reason to turn it into a generic abort_completion() function...
> Finally, clear_thread_flag(TIF_SIGPENDING) in sh_msiof_wait_for_completion()
> looks wrong. Or it is only for kthreads?
If I don't clear that flag, the next (by the same thread[*])
wait_for_completion_interruptible() will abort immediately.
[*] Typically this is the spi message pump worker.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
^ permalink raw reply [flat|nested] 8+ messages in thread
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2017-05-05 9:49 [PATCH/RFC] signal: Export signal_wake_up_state() to modules Geert Uytterhoeven
2017-05-05 10:07 ` Christoph Hellwig
2017-05-05 10:13 ` Geert Uytterhoeven
2017-05-05 11:08 ` Geert Uytterhoeven
2017-05-05 11:22 ` Christoph Hellwig
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