thinkpad-acpi: kill hotkey_thread_mutex
thinkpad-acpi: kill hotkey_thread_mutex

hotkey_kthread() does try_to_freeze() under hotkey_thread_mutex.

We can simply kill this mutex, hotkey_poll_stop_sync() does not need to
serialize with hotkey_kthread().  When kthread_stop() returns the thread
is already dead, it called do_exit()->complete_vfork_done().

Reported-by: Artem Savkov <672a66a96f26f23f0031682b30e14c9e2077e238@gmail.com>
Reported-by: Maciej Rutecki <b9fc5ee32e9bcd79c24fe827a77b4d80fdc0a8e2@gmail.com>
Signed-off-by: Oleg Nesterov <20b70f0af00562e63758b9ee42012ecc96c58590@redhat.com>
Acked-by: Henrique de Moraes Holschuh <1416ae054606eb9be8fa0d7696a4ddff667a3601@hmh.eng.br>
Cc: Matthew Garrett <d1dada306f6f6bc535ec5238317ee8d221588a1a@nebula.com>
Cc: "Rafael J. Wysocki" <a11f87183a953ab11f50fbafff689c5a7fa3506c@sisk.pl>
Reviewed-by: Mandeep Singh Baines <19acf4ef1f391f4aab404dc5703cac3632e06f3a@chromium.org>
Cc: Aaron Lu <e835aaae27ef45c770cbc83733586d01aadc3a43@intel.com>
Cc: Tejun Heo <546b05909706652891a87f7bfe385ae147f61f91@kernel.org>
Signed-off-by: Andrew Morton <5c1e68b099950c134891f0b6e179498a8ebe9cf9@linux-foundation.org>
Signed-off-by: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs