From: Martin Fuzzey <mfuzzey@parkeon.com>
To: "Luis R. Rodriguez" <mcgrof@kernel.org>
Cc: Linux FS Devel <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>,
"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: Fri, 9 Jun 2017 09:40:47 +0200 [thread overview]
Message-ID: <593A50FF.40604@parkeon.com> (raw)
In-Reply-To: <CAB=NE6UQZMmLvxTu7RcFHh3neAh+RFpTTFCSwJ8_EsmmtEq94Q@mail.gmail.com>
On 09/06/17 03:57, Luis R. Rodriguez wrote:
> On Thu, Jun 8, 2017 at 6:10 PM, Luis R. Rodriguez <mcgrof@kernel.org> wrote:
>>> 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)
> Martin just to be clear, by "normal case termination" do you mean
> completing successfully ?? Ie the firmware actually did make it onto
> the device ?
The firmware did *not* make it onto the device since the
request_firmware() call returned an error
(the code that would have transfered it to the device is only executed
following a successful request_firmware)
The process that terminates normally is unrelated to firmware loading as
I said above.
The only things that matter are:
- It is a child process of the process that calls request_firmware()
- It terminates *while* the the wait_ is still in progress
Here is a way of reproducing the problem using the test_firmware module
(which I only just saw) on normal linux with no Android or custom driver
#!/bin/sh
set -e
# Make sure the system firmware loader doesn't get in the way
/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 "/some/non/existing/file.bin" > "$DIR"/trigger_request;
If run with the "sleep 2 &" it terminates after 2 seconds
If the sleep is commented it runs for the expected 10 seconds (the
firmware loading timeout)
Since the sleep process is a child of the script process requesting a
firmware load its death causes a SIGCHLD causing request_firmware() to
abort prematurely.
Martin
next prev parent reply other threads:[~2017-06-09 7:40 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
2017-06-09 1:10 ` Luis R. Rodriguez
2017-06-09 1:57 ` Luis R. Rodriguez
2017-06-09 7:40 ` Martin Fuzzey [this message]
2017-06-09 21:12 ` Luis R. Rodriguez
2017-06-09 22:55 ` Luis R. Rodriguez
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