path: root/drivers/video/tegra/dc/dc.c
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authorWill Deacon <>2012-08-24 12:36:47 +0000
committerVarun Colbert <>2012-09-10 14:29:16 -0700
commitc56d1413ee5fb5ae24f36e9e7b8e578f3d91db15 (patch)
tree1625266bffc2ba0a267cf8decd7f97af8037c52e /drivers/video/tegra/dc/dc.c
parent12e80cc40856953f48240d4fdb6c2016a0afbdfd (diff)
ARM: 7467/1: mutex: use generic xchg-based implementation for ARMv6+
The open-coded mutex implementation for ARMv6+ cores suffers from a severe lack of barriers, so in the uncontended case we don't actually protect any accesses performed during the critical section. Furthermore, the code is largely a duplication of the ARMv6+ atomic_dec code but optimised to remove a branch instruction, as the mutex fastpath was previously inlined. Now that this is executed out-of-line, we can reuse the atomic access code for the locking (in fact, we use the xchg code as this produces shorter critical sections). This patch uses the generic xchg based implementation for mutexes on ARMv6+, which introduces barriers to the lock/unlock operations and also has the benefit of removing a fair amount of inline assembly code. Change-Id: I58e3ca4d2740a834d30b54fc35742fa2df7792ad Cc: <> : 0bce9c46: mutex: Place lock in contended... Cc: <> Acked-by: Arnd Bergmann <> Acked-by: Nicolas Pitre <> Reported-by: Shan Kang <> Signed-off-by: Will Deacon <> Signed-off-by: Russell King <> Reviewed-on: http://git-master/r/130940 Reviewed-by: Automatic_Commit_Validation_User Reviewed-by: Bharat Nihalani <> Tested-by: Bharat Nihalani <>
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