futex: Fix OWNER_DEAD fixup
authorPeter Zijlstra <peterz@infradead.org>
Mon, 22 Jan 2018 10:39:47 +0000 (11:39 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sat, 3 Feb 2018 16:38:47 +0000 (17:38 +0100)
commitd383a4277b75f3305d78006bb8de673cd17d04a5
treeb894e024202fc59f674e01e14345a1d8c10886f4
parent6c70076667f246dc200c7a3e9aeabd2f8f388416
futex: Fix OWNER_DEAD fixup

commit a97cb0e7b3f4c6297fd857055ae8e895f402f501 upstream.

Both Geert and DaveJ reported that the recent futex commit:

  c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")

introduced a problem with setting OWNER_DEAD. We set the bit on an
uninitialized variable and then entirely optimize it away as a
dead-store.

Move the setting of the bit to where it is more useful.

Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@us.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
Link: http://lkml.kernel.org/r/20180122103947.GD2228@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Ozkan Sezer <sezeroz@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kernel/futex.c