Will Deacon c14c338cb0 kernel/spinlock.c: add default arch_*_relax definitions for GENERIC_LOCKBREAK ...

When running with GENERIC_LOCKBREAK=y, the locking implementations emit
calls to arch_{read,write,spin}_relax when spinning on a contended lock
in order to allow architectures to favour the CPU owning the lock if
possible.

In reality, everybody apart from PowerPC and S390 just does cpu_relax()
here, so make that the default behaviour and allow it to be overridden
if required.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2013-09-11 15:58:21 -07:00

9.8 KiB

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