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| author | Josh Triplett <josh@joshtriplett.org> | 2014-04-07 15:39:45 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-04-07 16:36:14 -0700 |
| commit | 64b47e8fdb40a0d46e8cf458dd3e24f8afa073f6 (patch) | |
| tree | 284e2335ba622406f3d3437c2abd416cc8979294 | |
| parent | 188a81409ff7de1c5aae947a96356ddd8ff4aaa3 (diff) | |
| download | linux-stable-64b47e8fdb40a0d46e8cf458dd3e24f8afa073f6.tar.gz linux-stable-64b47e8fdb40a0d46e8cf458dd3e24f8afa073f6.tar.bz2 linux-stable-64b47e8fdb40a0d46e8cf458dd3e24f8afa073f6.zip | |
lglock: map to spinlock when !CONFIG_SMP
When the system has only one CPU, lglock is effectively a spinlock; map
it directly to spinlock to eliminate the indirection and duplicate code.
In addition to removing overhead, this drops 1.6k of code with a
defconfig modified to have !CONFIG_SMP, and 1.1k with a minimal config.
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: David Howells <dhowells@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | include/linux/lglock.h | 16 | ||||
| -rw-r--r-- | kernel/locking/Makefile | 3 |
2 files changed, 18 insertions, 1 deletions
diff --git a/include/linux/lglock.h b/include/linux/lglock.h index 96549abe8842..0081f000e34b 100644 --- a/include/linux/lglock.h +++ b/include/linux/lglock.h @@ -25,6 +25,8 @@ #include <linux/cpu.h> #include <linux/notifier.h> +#ifdef CONFIG_SMP + #ifdef CONFIG_DEBUG_LOCK_ALLOC #define LOCKDEP_INIT_MAP lockdep_init_map #else @@ -57,4 +59,18 @@ void lg_local_unlock_cpu(struct lglock *lg, int cpu); void lg_global_lock(struct lglock *lg); void lg_global_unlock(struct lglock *lg); +#else +/* When !CONFIG_SMP, map lglock to spinlock */ +#define lglock spinlock +#define DEFINE_LGLOCK(name) DEFINE_SPINLOCK(name) +#define DEFINE_STATIC_LGLOCK(name) static DEFINE_SPINLOCK(name) +#define lg_lock_init(lg, name) spin_lock_init(lg) +#define lg_local_lock spin_lock +#define lg_local_unlock spin_unlock +#define lg_local_lock_cpu(lg, cpu) spin_lock(lg) +#define lg_local_unlock_cpu(lg, cpu) spin_unlock(lg) +#define lg_global_lock spin_lock +#define lg_global_unlock spin_unlock +#endif + #endif diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile index 306a76b51e0f..b8bdcd4785b7 100644 --- a/kernel/locking/Makefile +++ b/kernel/locking/Makefile @@ -1,5 +1,5 @@ -obj-y += mutex.o semaphore.o rwsem.o lglock.o mcs_spinlock.o +obj-y += mutex.o semaphore.o rwsem.o mcs_spinlock.o ifdef CONFIG_FUNCTION_TRACER CFLAGS_REMOVE_lockdep.o = -pg @@ -14,6 +14,7 @@ ifeq ($(CONFIG_PROC_FS),y) obj-$(CONFIG_LOCKDEP) += lockdep_proc.o endif obj-$(CONFIG_SMP) += spinlock.o +obj-$(CONFIG_SMP) += lglock.o obj-$(CONFIG_PROVE_LOCKING) += spinlock.o obj-$(CONFIG_RT_MUTEXES) += rtmutex.o obj-$(CONFIG_DEBUG_RT_MUTEXES) += rtmutex-debug.o |