Peter Zijlstra 035688290a locking,qspinlock: Fix spin_is_locked() and spin_unlock_wait() ... commit 54cf809b95 upstream. Similar to commits: 51d7d5205d ("powerpc: Add smp_mb() to arch_spin_is_locked()") d86b8da04d ("arm64: spinlock: serialise spin_unlock_wait against concurrent lockers") qspinlock suffers from the fact that the _Q_LOCKED_VAL store is unordered inside the ACQUIRE of the lock. And while this is not a problem for the regular mutual exclusive critical section usage of spinlocks, it breaks creative locking like: spin_lock(A) spin_lock(B) spin_unlock_wait(B) if (!spin_is_locked(A)) do_something() do_something() In that both CPUs can end up running do_something at the same time, because our _Q_LOCKED_VAL store can drop past the spin_unlock_wait() spin_is_locked() loads (even on x86!!). To avoid making the normal case slower, add smp_mb()s to the less used spin_unlock_wait() / spin_is_locked() side of things to avoid this problem. Reported-and-tested-by: Davidlohr Bueso <dave@stgolabs.net> Reported-by: Giovanni Gherdovich <ggherdovich@suse.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2016-06-01 12:15:53 -07:00
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acpi	Merge branch 'acpi-pci'	2015-11-07 01:30:10 +01:00
asm-generic	locking,qspinlock: Fix spin_is_locked() and spin_unlock_wait()	2016-06-01 12:15:53 -07:00
clocksource
crypto	crypto: af_alg - Allow af_af_alg_release_parent to be called on nokey path	2016-02-17 12:31:03 -08:00
drm	drm: Loongson-3 doesn't fully support wc memory	2016-05-04 14:48:46 -07:00
dt-bindings	ARM: DT updates for v4.4	2015-11-10 15:06:26 -08:00
keys
kvm	KVM: arm/arm64: arch_timer: Preserve physical dist. active state on LR.active	2015-11-24 18:07:40 +01:00
linux	Fix OpenSSH pty regression on close	2016-06-01 12:15:52 -07:00
math-emu
media	videobuf2-core: Check user space planes array in dqbuf	2016-05-04 14:48:50 -07:00
memory
misc
net	net_sched: update hierarchical backlog too	2016-05-18 17:06:39 -07:00
pcmcia
ras
rdma	IB/security: Restrict use of the write() interface	2016-05-04 14:48:48 -07:00
rxrpc
scsi	Merge branch 'mkp-fixes' into fixes	2015-12-03 09:32:33 -08:00
soc	ARM: SoC driver updates for v4.4	2015-11-10 15:00:03 -08:00
sound	ALSA: rawmidi: Make snd_rawmidi_transmit() race-free	2016-02-17 12:30:58 -08:00
target	target: Fix WRITE_SAME/DISCARD conversion to linux 512b sectors	2016-03-09 15:34:51 -08:00
trace	Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux	2015-11-11 09:03:01 -08:00
uapi	uapi glibc compat: fix compile errors when glibc net/if.h included before linux/if.h MIME-Version: 1.0	2016-05-18 17:06:43 -07:00
video	gpu: ipu-v3: drop unused dmfc field from client platform data	2015-11-24 11:30:15 +01:00
xen	xen: Fix page <-> pfn conversion on 32 bit systems	2016-05-11 11:21:14 +02:00
Kbuild