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| author | Ingo Molnar <mingo@elte.hu> | 2009-07-03 08:29:51 -0500 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2009-07-20 15:45:38 +0200 |
| commit | 15868172b33ea9006afd98b0089e5b4fdb3da2c7 (patch) | |
| tree | b866796f58f99db77a7e72c2b17871cdd970c2d9 /include/linux/percpu.h | |
| parent | 78af08d90b8f745044b1274430bc4bc6b2b27aca (diff) | |
| download | lwn-15868172b33ea9006afd98b0089e5b4fdb3da2c7.tar.gz lwn-15868172b33ea9006afd98b0089e5b4fdb3da2c7.zip | |
percpu: add percpu locked infrastructure
RT needs per cpu data structures protected by per cpu locks instead of
disabling preemption. Add the infrastructure for per cpu locked data.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'include/linux/percpu.h')
| -rw-r--r-- | include/linux/percpu.h | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/include/linux/percpu.h b/include/linux/percpu.h index 26fd9d12f050..39c4f01d2cd4 100644 --- a/include/linux/percpu.h +++ b/include/linux/percpu.h @@ -32,6 +32,29 @@ &__get_cpu_var(var); })) #define put_cpu_var(var) preempt_enable() +/* + * Per-CPU data structures with an additional lock - useful for + * PREEMPT_RT code that wants to reschedule but also wants + * per-CPU data structures. + * + * 'cpu' gets updated with the CPU the task is currently executing on. + * + * NOTE: on normal !PREEMPT_RT kernels these per-CPU variables + * are the same as the normal per-CPU variables, so there no + * runtime overhead. + */ +#define get_cpu_var_locked(var, cpuptr) \ +(*({ \ + int __cpu = raw_smp_processor_id(); \ + \ + *(cpuptr) = __cpu; \ + spin_lock(&__get_cpu_lock(var, __cpu)); \ + &__get_cpu_var_locked(var, __cpu); \ +})) + +#define put_cpu_var_locked(var, cpu) \ + do { (void)cpu; spin_unlock(&__get_cpu_lock(var, cpu)); } while (0) + #ifdef CONFIG_SMP #ifdef CONFIG_HAVE_DYNAMIC_PER_CPU_AREA |