diff options
| -rw-r--r-- | arch/powerpc/kernel/time.c | 24 |
1 files changed, 15 insertions, 9 deletions
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index 2c8564d54e4..0a8a820672f 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -222,19 +222,28 @@ struct cpu_purr_data { int initialized; /* thread is running */ u64 tb; /* last TB value read */ u64 purr; /* last PURR value read */ - spinlock_t lock; }; +/* + * Each entry in the cpu_purr_data array is manipulated only by its + * "owner" cpu -- usually in the timer interrupt but also occasionally + * in process context for cpu online. As long as cpus do not touch + * each others' cpu_purr_data, disabling local interrupts is + * sufficient to serialize accesses. + */ static DEFINE_PER_CPU(struct cpu_purr_data, cpu_purr_data); static void snapshot_tb_and_purr(void *data) { + unsigned long flags; struct cpu_purr_data *p = &__get_cpu_var(cpu_purr_data); + local_irq_save(flags); p->tb = mftb(); p->purr = mfspr(SPRN_PURR); wmb(); p->initialized = 1; + local_irq_restore(flags); } /* @@ -242,15 +251,14 @@ static void snapshot_tb_and_purr(void *data) */ void snapshot_timebases(void) { - int cpu; - if (!cpu_has_feature(CPU_FTR_PURR)) return; - for_each_possible_cpu(cpu) - spin_lock_init(&per_cpu(cpu_purr_data, cpu).lock); on_each_cpu(snapshot_tb_and_purr, NULL, 0, 1); } +/* + * Must be called with interrupts disabled. + */ void calculate_steal_time(void) { u64 tb, purr; @@ -262,7 +270,6 @@ void calculate_steal_time(void) pme = &per_cpu(cpu_purr_data, smp_processor_id()); if (!pme->initialized) return; /* this can happen in early boot */ - spin_lock(&pme->lock); tb = mftb(); purr = mfspr(SPRN_PURR); stolen = (tb - pme->tb) - (purr - pme->purr); @@ -270,7 +277,6 @@ void calculate_steal_time(void) account_steal_time(current, stolen); pme->tb = tb; pme->purr = purr; - spin_unlock(&pme->lock); } /* @@ -284,12 +290,12 @@ static void snapshot_purr(void) if (!cpu_has_feature(CPU_FTR_PURR)) return; + local_irq_save(flags); pme = &per_cpu(cpu_purr_data, smp_processor_id()); - spin_lock_irqsave(&pme->lock, flags); pme->tb = mftb(); pme->purr = mfspr(SPRN_PURR); pme->initialized = 1; - spin_unlock_irqrestore(&pme->lock, flags); + local_irq_restore(flags); } #endif /* CONFIG_PPC_SPLPAR */ |