tree e9a28c0a9483efd2985754bd739a10d01040d3df
parent 1b988daf47a7b088afcd486450411f5a1fa98840
author Rodrigo Rivas Costa <rodrigorivascosta@gmail.com> 1552676950 +0100
committer Siarhei Vishniakou <svv@google.com> 1573142549 +0000

UPSTREAM: HID: steam: fix deadlock with input devices.

When using this driver with the wireless dongle and some usermode
program that monitors every input device (acpid, for example), while
another usermode client opens and closes the low-level device
repeadedly, the system eventually deadlocks.

The reason is that steam_input_register_device() must not be called with
the mutex held, because the input subsystem has its own synchronization
that clashes with this one: it is possible that steam_input_open() is
called before input_register_device() returns, and since
steam_input_open() needs to lock the mutex, it deadlocks.

However we must hold the mutex when calling any function that sends
commands to the controller. If not, random commands end up falling fail.

(cherry picked from commit 6b538cc21334b83f09b25dec4aa2d2726bf07ed0 ("HID: steam: fix deadlock with input devices."))
https://github.com/torvalds/linux/commit/6b538cc21334b83f09b25dec4aa2d2726bf07ed0

Bug: 136263708

Reported-by: Simon Gene Gottlieb <simon@gottliebtfreitag.de>
Signed-off-by: Rodrigo Rivas Costa <rodrigorivascosta@gmail.com>
Tested-by: Simon Gene Gottlieb <simon@gottliebtfreitag.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Siarhei Vishniakou <svv@google.com>
Change-Id: Ia0c37b3117dc605a30b2e1fb5030282bf2e11a11