From: Martin Fuzzey <mfuzzey@parkeon.com>
To: "Luis R. Rodriguez" <mcgrof@kernel.org>,
linux-fsdevel@vger.kernel.org, Alan Cox <alan@linux.intel.com>,
"Ted Ts'o" <tytso@mit.edu>, Andy Lutomirski <luto@kernel.org>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>,
Linux API <linux-api@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Greg KH <gregkh@linuxfoundation.org>,
Daniel Wagner <wagi@monom.org>,
David Woodhouse <dwmw2@infradead.org>,
jewalt@lgsinnovations.com, rafal@milecki.pl,
Arend Van Spriel <arend.vanspriel@broadcom.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
"Li, Yi" <yi1.li@linux.intel.com>,
atull@opensource.altera.com,
Moritz Fischer <moritz.fischer@ettus.com>,
Petr Mladek <pmladek@suse.com>,
Johannes Berg <johannes.berg@intel.com>,
Emmanuel Grumbach <emmanuel.grumbach@intel.com>,
Luca Coelho <luciano.coelho@intel.com>,
Kalle Valo <kvalo@codeaurora.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Kees Cook <keescook@chromium.org>,
AKASHI Takahiro <takahiro.akashi@linaro.org>,
David Howells <dhowells@redhat.com>,
Peter Jones <pjones@redhat.com>,
Hans de Goede <hdegoede@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] firmware: fix sending -ERESTARTSYS due to signal on fallback
Date: Wed, 7 Jun 2017 19:54:34 +0200 [thread overview]
Message-ID: <59383DDA.3040702@parkeon.com> (raw)
In-Reply-To: <20170607170858.GK27288@wotan.suse.de>
On 07/06/17 19:08, Luis R. Rodriguez wrote:
> On Thu, May 25, 2017 at 10:28:38AM +0200, Fuzzey, Martin wrote:
>> 1) Android init calls write() on the sysfs file
>> 2) The sysfs .store() callback registered by a driver is called
>> 3) The driver calls request_firmware()
>> 4) request_firmware() sends the firmware load request to userspace and
>> calls wait_for_completion_interruptible()
> Martin, just for completeness on documenting on the commit log of the next
> swait proposed fix for this -- what signal did the process get from which you
> note the child dies below ? Exactly what in Android sent this signal ?
Android didn't send the signal, the kernel did (SIGCHLD).
Like this:
1) Android init (pid=1) fork()s (say pid=42) [this child process is
totally unrelated to firmware loading]
2) Android init (pid=1) does a write() on a (driver custom) sysfs file
which ends up calling request_firmware() kernel side
3) The firmware loading fallback mechanism is used, the request is sent
to userspace and pid 1 waits in the kernel on wait_*
4) before firmware loading completes pid 42 dies (for any reason - in my
case normal termination)
5) Kernel delivers SIGCHLD to pid=1 to tell it a child has died, which
causes -ERESTARTSYS to be returned from wait_*
Martin
next prev parent reply other threads:[~2017-06-07 17:54 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-23 13:16 [PATCH] firmware: request_firmware() should propagate -ERESTARTSYS Martin Fuzzey
2017-05-23 13:31 ` Greg Kroah-Hartman
2017-05-23 14:32 ` Martin Fuzzey
2017-05-23 19:55 ` Luis R. Rodriguez
2017-05-24 20:56 ` Luis R. Rodriguez
2017-05-24 21:40 ` [PATCH v2] firmware: fix sending -ERESTARTSYS due to signal on fallback Luis R. Rodriguez
2017-05-24 22:00 ` Andy Lutomirski
2017-05-24 22:38 ` Luis R. Rodriguez
2017-05-25 4:13 ` Andy Lutomirski
2017-05-25 8:28 ` Fuzzey, Martin
2017-05-26 11:09 ` Eric W. Biederman
2017-05-26 19:46 ` Luis R. Rodriguez
2017-05-26 21:26 ` Dmitry Torokhov
2017-05-26 21:32 ` Luis R. Rodriguez
2017-05-26 21:55 ` Dmitry Torokhov
2017-06-05 20:24 ` Luis R. Rodriguez
2017-06-06 9:04 ` Martin Fuzzey
2017-06-06 16:34 ` Luis R. Rodriguez
2017-06-06 17:52 ` Luis R. Rodriguez
2017-06-06 14:53 ` Alan Cox
2017-06-06 16:47 ` Luis R. Rodriguez
2017-06-06 17:54 ` Luis R. Rodriguez
2017-06-06 22:11 ` Theodore Ts'o
2017-06-07 0:22 ` Luis R. Rodriguez
2017-06-07 4:56 ` Andy Lutomirski
2017-06-07 6:25 ` Dmitry Torokhov
2017-06-07 12:25 ` Alan Cox
2017-06-07 17:15 ` Luis R. Rodriguez
2017-06-09 1:14 ` Andy Lutomirski
2017-06-09 1:33 ` Luis R. Rodriguez
2017-06-09 21:29 ` Luis R. Rodriguez
2017-05-26 19:40 ` Luis R. Rodriguez
2017-05-26 20:23 ` Fuzzey, Martin
2017-05-26 20:52 ` Luis R. Rodriguez
2017-06-07 17:08 ` Luis R. Rodriguez
2017-06-07 17:54 ` Martin Fuzzey [this message]
2017-06-09 1:10 ` Luis R. Rodriguez
2017-06-09 1:57 ` Luis R. Rodriguez
2017-06-09 7:40 ` Martin Fuzzey
2017-06-09 21:12 ` Luis R. Rodriguez
2017-06-09 22:55 ` Luis R. Rodriguez
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