Now that all the task runtime clock users are gone, remove the ugly rq->lock usage from perf counters, which solves the nasty deadlock seen when a software task clock counter was read from an NMI overflow context. Signed-off-by: Peter Zijlstra --- include/linux/kernel_stat.h | 2 -- kernel/perf_counter.c | 42 ++++++++++++++++-------------------------- kernel/sched.c | 20 -------------------- 3 files changed, 16 insertions(+), 48 deletions(-) Index: linux-2.6/include/linux/kernel_stat.h =================================================================== --- linux-2.6.orig/include/linux/kernel_stat.h +++ linux-2.6/include/linux/kernel_stat.h @@ -85,8 +85,6 @@ static inline unsigned int kstat_irqs(un /* * Lock/unlock the current runqueue - to extract task statistics: */ -extern void curr_rq_lock_irq_save(unsigned long *flags); -extern void curr_rq_unlock_irq_restore(unsigned long *flags); extern unsigned long long __task_delta_exec(struct task_struct *tsk, int update); extern unsigned long long task_delta_exec(struct task_struct *); Index: linux-2.6/kernel/perf_counter.c =================================================================== --- linux-2.6.orig/kernel/perf_counter.c +++ linux-2.6/kernel/perf_counter.c @@ -172,8 +172,7 @@ static void __perf_counter_remove_from_c if (ctx->task && cpuctx->task_ctx != ctx) return; - curr_rq_lock_irq_save(&flags); - spin_lock(&ctx->lock); + spin_lock_irqsave(&ctx->lock, flags); counter_sched_out(counter, cpuctx, ctx); @@ -198,8 +197,7 @@ static void __perf_counter_remove_from_c perf_max_counters - perf_reserved_percpu); } - spin_unlock(&ctx->lock); - curr_rq_unlock_irq_restore(&flags); + spin_unlock_irqrestore(&ctx->lock, flags); } @@ -319,8 +317,7 @@ static void __perf_counter_disable(void if (ctx->task && cpuctx->task_ctx != ctx) return; - curr_rq_lock_irq_save(&flags); - spin_lock(&ctx->lock); + spin_lock_irqsave(&ctx->lock, flags); /* * If the counter is on, turn it off. @@ -336,8 +333,7 @@ static void __perf_counter_disable(void counter->state = PERF_COUNTER_STATE_OFF; } - spin_unlock(&ctx->lock); - curr_rq_unlock_irq_restore(&flags); + spin_unlock_irqrestore(&ctx->lock, flags); } /* @@ -515,8 +511,7 @@ static void __perf_install_in_context(vo if (ctx->task && cpuctx->task_ctx != ctx) return; - curr_rq_lock_irq_save(&flags); - spin_lock(&ctx->lock); + spin_lock_irqsave(&ctx->lock, flags); update_context_time(ctx); /* @@ -565,8 +560,7 @@ static void __perf_install_in_context(vo unlock: hw_perf_restore(perf_flags); - spin_unlock(&ctx->lock); - curr_rq_unlock_irq_restore(&flags); + spin_unlock_irqrestore(&ctx->lock, flags); } /* @@ -641,8 +635,7 @@ static void __perf_counter_enable(void * if (ctx->task && cpuctx->task_ctx != ctx) return; - curr_rq_lock_irq_save(&flags); - spin_lock(&ctx->lock); + spin_lock_irqsave(&ctx->lock, flags); update_context_time(ctx); counter->prev_state = counter->state; @@ -678,8 +671,7 @@ static void __perf_counter_enable(void * } unlock: - spin_unlock(&ctx->lock); - curr_rq_unlock_irq_restore(&flags); + spin_unlock_irqrestore(&ctx->lock, flags); } /* @@ -971,7 +963,7 @@ int perf_counter_task_disable(void) if (likely(!ctx->nr_counters)) return 0; - curr_rq_lock_irq_save(&flags); + local_irq_save(flags); cpu = smp_processor_id(); perf_counter_task_sched_out(curr, cpu); @@ -992,9 +984,7 @@ int perf_counter_task_disable(void) hw_perf_restore(perf_flags); - spin_unlock(&ctx->lock); - - curr_rq_unlock_irq_restore(&flags); + spin_unlock_irqrestore(&ctx->lock, flags); return 0; } @@ -1011,7 +1001,7 @@ int perf_counter_task_enable(void) if (likely(!ctx->nr_counters)) return 0; - curr_rq_lock_irq_save(&flags); + local_irq_save(flags); cpu = smp_processor_id(); perf_counter_task_sched_out(curr, cpu); @@ -1037,7 +1027,7 @@ int perf_counter_task_enable(void) perf_counter_task_sched_in(curr, cpu); - curr_rq_unlock_irq_restore(&flags); + local_irq_restore(flags); return 0; } @@ -1095,12 +1085,12 @@ static void __read(void *info) struct perf_counter_context *ctx = counter->ctx; unsigned long flags; - curr_rq_lock_irq_save(&flags); + local_irq_save(flags); if (ctx->is_active) update_context_time(ctx); counter->hw_ops->read(counter); update_counter_times(counter); - curr_rq_unlock_irq_restore(&flags); + local_irq_restore(flags); } static u64 perf_counter_read(struct perf_counter *counter) @@ -2890,7 +2880,7 @@ __perf_counter_exit_task(struct task_str * Be careful about zapping the list - IRQ/NMI context * could still be processing it: */ - curr_rq_lock_irq_save(&flags); + local_irq_save(flags); perf_flags = hw_perf_save_disable(); cpuctx = &__get_cpu_var(perf_cpu_context); @@ -2903,7 +2893,7 @@ __perf_counter_exit_task(struct task_str child_ctx->nr_counters--; hw_perf_restore(perf_flags); - curr_rq_unlock_irq_restore(&flags); + local_irq_restore(flags); } parent_counter = child_counter->parent; Index: linux-2.6/kernel/sched.c =================================================================== --- linux-2.6.orig/kernel/sched.c +++ linux-2.6/kernel/sched.c @@ -1004,26 +1004,6 @@ static struct rq *task_rq_lock(struct ta } } -void curr_rq_lock_irq_save(unsigned long *flags) - __acquires(rq->lock) -{ - struct rq *rq; - - local_irq_save(*flags); - rq = cpu_rq(smp_processor_id()); - spin_lock(&rq->lock); -} - -void curr_rq_unlock_irq_restore(unsigned long *flags) - __releases(rq->lock) -{ - struct rq *rq; - - rq = cpu_rq(smp_processor_id()); - spin_unlock(&rq->lock); - local_irq_restore(*flags); -} - void task_rq_unlock_wait(struct task_struct *p) { struct rq *rq = task_rq(p); 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