From: Martin Fuzzey <mfuzzey@parkeon.com>
To: "Luis R. Rodriguez" <mcgrof@kernel.org>, gregkh@linuxfoundation.org
Cc: ebiederm@xmission.com, dmitry.torokhov@gmail.com, wagi@monom.org,
dwmw2@infradead.org, jewalt@lgsinnovations.com, rafal@milecki.pl,
arend.vanspriel@broadcom.com, rjw@rjwysocki.net,
yi1.li@linux.intel.com, atull@kernel.org,
moritz.fischer@ettus.com, pmladek@suse.com,
johannes.berg@intel.com, emmanuel.grumbach@intel.com,
luciano.coelho@intel.com, kvalo@codeaurora.org, luto@kernel.org,
torvalds@linux-foundation.org, keescook@chromium.org,
takahiro.akashi@linaro.org, dhowells@redhat.com,
pjones@redhat.com, hdegoede@redhat.com, alan@linux.intel.com,
tytso@mit.edu, mtk.manpages@gmail.com,
paul.gortmaker@windriver.com, mtosatti@redhat.com,
mawilcox@microsoft.com, linux-api@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/4] firmware: fix fallback mechanism by ignoring SIGCHLD
Date: Thu, 15 Jun 2017 09:49:18 +0200 [thread overview]
Message-ID: <59423BFE.3060405@parkeon.com> (raw)
In-Reply-To: <20170614222017.14653-1-mcgrof@kernel.org>
On 15/06/17 00:20, Luis R. Rodriguez wrote:
> Martin reported an issue with Android where if sysfs is used to trigger a sync
> fw load which *relies* on the fallback mechanism and a background job completes
> while the trigger is ongoing in the foreground it will immediately fail the fw
> request. The issue can be observed in this simple test script using the
> test_firmware driver:
>
> set -e
> /etc/init.d/udev stop
> modprobe test_firmware
> DIR=/sys/devices/virtual/misc/test_firmware
> echo 10 >/sys/class/firmware/timeout
> sleep 2 &
> echo -n "does-not-exist-file.bin" > "$DIR"/trigger_request
>
> The background sleep triggers the SIGCHLD signal and we fail the firmware
> request on the fallback mechanism. This was due to the type of wait used which
> ...
>
> Note that although I *feared* this might implicate any use of non-killable waits
> on other system calls, such as finit_module(), initial testing confirms this to
> not be the case. For instance replacing the echo with modprobe on a module
> which does the same on init does not present the same issues. This could be due
> to the special SA_RESTART flag case on write() as noted above and sysfs...
> however, its not perfectly clear yet to me.
>
>
The reason the problem does not occur with modprobe is that in that case
the processes triggering the firmware load
(modprobe) and the process dying (sleep) are *siblings* rather than
father and child.
So the modprobe process does *not* receive a SIGCHLD when its' *brother*
dies.
echo is a shell built-in so the process triggering the firmware load
(the shell) and the process dying (sleep) *are* father and child.
Martin
next prev parent reply other threads:[~2017-06-15 7:49 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-14 22:20 [PATCH 0/4] firmware: fix fallback mechanism by ignoring SIGCHLD Luis R. Rodriguez
2017-06-14 22:20 ` [PATCH 1/4] test_firmware: add test case for SIGCHLD on sync fallback Luis R. Rodriguez
2017-06-14 22:20 ` [PATCH 2/4] swait: add the missing killable swaits Luis R. Rodriguez
[not found] ` <20170614222017.14653-3-mcgrof-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2017-06-29 12:54 ` Greg KH
[not found] ` <20170629125402.GH26046-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
2017-06-29 13:05 ` Thomas Gleixner
2017-06-29 13:35 ` Greg KH
2017-06-29 13:46 ` Thomas Gleixner
2017-06-29 16:13 ` Linus Torvalds
2017-06-29 16:31 ` Matthew Wilcox
2017-06-29 17:29 ` Luis R. Rodriguez
2017-06-29 17:40 ` Davidlohr Bueso
2017-06-29 17:57 ` Linus Torvalds
2017-06-29 18:33 ` Davidlohr Bueso
[not found] ` <20170629183339.GD3954-3dK4OQgjB4rH06JGZaSw0A@public.gmane.org>
2017-06-29 18:59 ` Linus Torvalds
[not found] ` <CA+55aFz8Mhx+A-g-5yOG-O1ZLRUR_fpeeA4iBNGH8EnDBZEdpA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-06-29 19:40 ` Luis R. Rodriguez
2017-06-29 19:44 ` Luis R. Rodriguez
[not found] ` <20170629194455.GR21846-B4tOwbsTzaBolqkO4TVVkw@public.gmane.org>
2017-06-29 20:58 ` Jakub Kicinski
2017-06-29 22:50 ` Luis R. Rodriguez
2017-06-29 22:53 ` Jakub Kicinski
2017-06-29 23:00 ` Luis R. Rodriguez
2017-06-29 23:06 ` Jakub Kicinski
[not found] ` <20170629225003.GU21846-B4tOwbsTzaBolqkO4TVVkw@public.gmane.org>
2017-07-12 21:33 ` Luis R. Rodriguez
[not found] ` <20170629194015.GQ21846-B4tOwbsTzaBolqkO4TVVkw@public.gmane.org>
2017-06-29 20:57 ` Linus Torvalds
2017-07-05 2:06 ` Davidlohr Bueso
[not found] ` <20170705020635.GD11168-3dK4OQgjB4rH06JGZaSw0A@public.gmane.org>
2017-07-07 19:58 ` Linus Torvalds
2017-07-07 22:27 ` Davidlohr Bueso
2017-07-07 22:48 ` Linus Torvalds
2017-06-29 19:15 ` Marcelo Tosatti
[not found] ` <20170629191506.GB12368-I4X2Mt4zSy4@public.gmane.org>
2017-06-30 4:03 ` Linus Torvalds
2017-06-30 11:55 ` Marcelo Tosatti
2017-06-30 11:57 ` Marcelo Tosatti
2017-06-30 17:30 ` Krister Johansen
2017-06-14 22:20 ` [PATCH 3/4] firmware: avoid invalid fallback aborts by using killable swait Luis R. Rodriguez
2017-06-14 22:20 ` [PATCH 4/4] firmware: send -EINTR on signal abort on fallback mechanism Luis R. Rodriguez
2017-06-15 7:49 ` Martin Fuzzey [this message]
[not found] ` <20170614222017.14653-1-mcgrof-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2017-06-26 21:19 ` [PATCH 0/4] firmware: fix fallback mechanism by ignoring SIGCHLD Luis R. Rodriguez
2017-06-29 15:14 ` Greg KH
[not found] ` <20170629151442.GA4880-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
2017-06-29 17:29 ` Luis R. Rodriguez
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