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perf_counter: remove rq->lock usage

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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 <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094518.531137582@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-04-06 11:45:12 +02:00 committed by Ingo Molnar
parent a39d6f2556
commit 849691a6cd
3 changed files with 16 additions and 48 deletions
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2
include/linux/kernel_stat.h
View File

@ -85,8 +85,6 @@ static inline unsigned int kstat_irqs(unsigned int irq)
/*
* 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 *);

42
kernel/perf_counter.c
View File

@ -172,8 +172,7 @@ static void __perf_counter_remove_from_context(void *info)
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_context(void *info)
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 *info)
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 *info)
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(void *info)
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(void *info)
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 *info)
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 *info)
}
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_struct *child,
* 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_struct *child,
child_ctx->nr_counters--;
hw_perf_restore(perf_flags);
curr_rq_unlock_irq_restore(&flags);
local_irq_restore(flags);
}
parent_counter = child_counter->parent;

20
kernel/sched.c
View File

@ -997,26 +997,6 @@ static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
}
}
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);