]> git.proxmox.com Git - mirror_ubuntu-disco-kernel.git/commit
arm64: spinlocks: implement smp_mb__before_spinlock() as smp_mb()
authorWill Deacon <will.deacon@arm.com>
Mon, 5 Sep 2016 10:56:05 +0000 (11:56 +0100)
committerCatalin Marinas <catalin.marinas@arm.com>
Fri, 9 Sep 2016 11:33:48 +0000 (12:33 +0100)
commit872c63fbf9e153146b07f0cece4da0d70b283eeb
tree86880c47da4f3557f5673fdb1cb3e00a660fff7d
parentc6935931c1894ff857616ff8549b61236a19148f
arm64: spinlocks: implement smp_mb__before_spinlock() as smp_mb()

smp_mb__before_spinlock() is intended to upgrade a spin_lock() operation
to a full barrier, such that prior stores are ordered with respect to
loads and stores occuring inside the critical section.

Unfortunately, the core code defines the barrier as smp_wmb(), which
is insufficient to provide the required ordering guarantees when used in
conjunction with our load-acquire-based spinlock implementation.

This patch overrides the arm64 definition of smp_mb__before_spinlock()
to map to a full smp_mb().

Cc: <stable@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Reported-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
arch/arm64/include/asm/spinlock.h