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| author | Will Deacon <will.deacon@arm.com> | 2013-09-11 14:23:23 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-09-11 15:58:21 -0700 |
| commit | c14c338cb05c700a260480c197cfd6da8f8b7d2e (patch) | |
| tree | 1c6ed14664b122f57b4a75cfbad02ede7106f285 /kernel | |
| parent | 60c323699bb308404dcb60e8808531e02651578a (diff) | |
| download | op-kernel-dev-c14c338cb05c700a260480c197cfd6da8f8b7d2e.zip op-kernel-dev-c14c338cb05c700a260480c197cfd6da8f8b7d2e.tar.gz | |
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>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/spinlock.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/kernel/spinlock.c b/kernel/spinlock.c index 5cdd806..4b082b5 100644 --- a/kernel/spinlock.c +++ b/kernel/spinlock.c @@ -34,6 +34,20 @@ #else #define raw_read_can_lock(l) read_can_lock(l) #define raw_write_can_lock(l) write_can_lock(l) + +/* + * Some architectures can relax in favour of the CPU owning the lock. + */ +#ifndef arch_read_relax +# define arch_read_relax(l) cpu_relax() +#endif +#ifndef arch_write_relax +# define arch_write_relax(l) cpu_relax() +#endif +#ifndef arch_spin_relax +# define arch_spin_relax(l) cpu_relax() +#endif + /* * We build the __lock_function inlines here. They are too large for * inlining all over the place, but here is only one user per function |
