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Commit 665c2142 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf_counter: Clean up task_ctx vs interrupts 



Remove the local_irq_save() etc.. in routines that are smp function
calls, or have IRQs disabled by other means.

Then change the COMM, MMAP, and swcounter context iteration to
current->perf_counter_ctxp and RCU, since it really doesn't matter
which context they iterate, they're all folded.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent efb3d172

kernel/perf_counter.c

+50 −32
Original line number Diff line number Diff line
@@ -232,18 +232,14 @@ static void __perf_counter_remove_from_context(void *info) 
	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);

	struct perf_counter *counter = info;

	struct perf_counter_context *ctx = counter->ctx;

	unsigned long flags;



	local_irq_save(flags);

	/*

	 * If this is a task context, we need to check whether it is

	 * the current task context of this cpu. If not it has been

	 * scheduled out before the smp call arrived.

	 */

	if (ctx->task && cpuctx->task_ctx != ctx) {

		local_irq_restore(flags);

	if (ctx->task && cpuctx->task_ctx != ctx)

		return;

	}



	spin_lock(&ctx->lock);

	/*
@@ -267,7 +263,7 @@ static void __perf_counter_remove_from_context(void *info) 
	}



	perf_enable();

	spin_unlock_irqrestore(&ctx->lock, flags);

	spin_unlock(&ctx->lock);

}
@@ -383,17 +379,13 @@ static void __perf_counter_disable(void *info) 
	struct perf_counter *counter = info;

	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);

	struct perf_counter_context *ctx = counter->ctx;

	unsigned long flags;



	local_irq_save(flags);

	/*

	 * If this is a per-task counter, need to check whether this

	 * counter's task is the current task on this cpu.

	 */

	if (ctx->task && cpuctx->task_ctx != ctx) {

		local_irq_restore(flags);

	if (ctx->task && cpuctx->task_ctx != ctx)

		return;

	}



	spin_lock(&ctx->lock);
@@ -411,7 +403,7 @@ static void __perf_counter_disable(void *info) 
		counter->state = PERF_COUNTER_STATE_OFF;

	}



	spin_unlock_irqrestore(&ctx->lock, flags);

	spin_unlock(&ctx->lock);

}



/*
@@ -618,10 +610,8 @@ static void __perf_install_in_context(void *info) 
	struct perf_counter_context *ctx = counter->ctx;

	struct perf_counter *leader = counter->group_leader;

	int cpu = smp_processor_id();

	unsigned long flags;

	int err;



	local_irq_save(flags);

	/*

	 * If this is a task context, we need to check whether it is

	 * the current task context of this cpu. If not it has been
@@ -630,10 +620,8 @@ static void __perf_install_in_context(void *info) 
	 * on this cpu because it had no counters.

	 */

	if (ctx->task && cpuctx->task_ctx != ctx) {

		if (cpuctx->task_ctx || ctx->task != current) {

			local_irq_restore(flags);

		if (cpuctx->task_ctx || ctx->task != current)

			return;

		}

		cpuctx->task_ctx = ctx;

	}
@@ -687,7 +675,7 @@ static void __perf_install_in_context(void *info) 
 unlock:

	perf_enable();



	spin_unlock_irqrestore(&ctx->lock, flags);

	spin_unlock(&ctx->lock);

}



/*
@@ -751,19 +739,15 @@ static void __perf_counter_enable(void *info) 
	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);

	struct perf_counter_context *ctx = counter->ctx;

	struct perf_counter *leader = counter->group_leader;

	unsigned long flags;

	int err;



	local_irq_save(flags);

	/*

	 * If this is a per-task counter, need to check whether this

	 * counter's task is the current task on this cpu.

	 */

	if (ctx->task && cpuctx->task_ctx != ctx) {

		if (cpuctx->task_ctx || ctx->task != current) {

			local_irq_restore(flags);

		if (cpuctx->task_ctx || ctx->task != current)

			return;

		}

		cpuctx->task_ctx = ctx;

	}
@@ -811,7 +795,7 @@ static void __perf_counter_enable(void *info) 
	}



 unlock:

	spin_unlock_irqrestore(&ctx->lock, flags);

	spin_unlock(&ctx->lock);

}



/*
@@ -981,6 +965,10 @@ void perf_counter_task_sched_out(struct task_struct *task, 
		spin_lock(&ctx->lock);

		spin_lock_nested(&next_ctx->lock, SINGLE_DEPTH_NESTING);

		if (context_equiv(ctx, next_ctx)) {

			/*

			 * XXX do we need a memory barrier of sorts

			 * wrt to rcu_dereference() of perf_counter_ctxp

			 */

			task->perf_counter_ctxp = next_ctx;

			next->perf_counter_ctxp = ctx;

			ctx->task = next;
@@ -998,6 +986,9 @@ void perf_counter_task_sched_out(struct task_struct *task, 
	}

}



/*

 * Called with IRQs disabled

 */

static void __perf_counter_task_sched_out(struct perf_counter_context *ctx)

{

	struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
@@ -1012,6 +1003,9 @@ static void __perf_counter_task_sched_out(struct perf_counter_context *ctx) 
	cpuctx->task_ctx = NULL;

}



/*

 * Called with IRQs disabled

 */

static void perf_counter_cpu_sched_out(struct perf_cpu_context *cpuctx)

{

	__perf_counter_sched_out(&cpuctx->ctx, cpuctx);
@@ -2431,6 +2425,7 @@ static void perf_counter_comm_ctx(struct perf_counter_context *ctx, 
static void perf_counter_comm_event(struct perf_comm_event *comm_event)

{

	struct perf_cpu_context *cpuctx;

	struct perf_counter_context *ctx;

	unsigned int size;

	char *comm = comm_event->task->comm;
@@ -2443,9 +2438,17 @@ static void perf_counter_comm_event(struct perf_comm_event *comm_event) 


	cpuctx = &get_cpu_var(perf_cpu_context);

	perf_counter_comm_ctx(&cpuctx->ctx, comm_event);

	if (cpuctx->task_ctx)

		perf_counter_comm_ctx(cpuctx->task_ctx, comm_event);

	put_cpu_var(perf_cpu_context);



	rcu_read_lock();

	/*

	 * doesn't really matter which of the child contexts the

	 * events ends up in.

	 */

	ctx = rcu_dereference(current->perf_counter_ctxp);

	if (ctx)

		perf_counter_comm_ctx(ctx, comm_event);

	rcu_read_unlock();

}



void perf_counter_comm(struct task_struct *task)
@@ -2536,6 +2539,7 @@ static void perf_counter_mmap_ctx(struct perf_counter_context *ctx, 
static void perf_counter_mmap_event(struct perf_mmap_event *mmap_event)

{

	struct perf_cpu_context *cpuctx;

	struct perf_counter_context *ctx;

	struct file *file = mmap_event->file;

	unsigned int size;

	char tmp[16];
@@ -2568,10 +2572,18 @@ static void perf_counter_mmap_event(struct perf_mmap_event *mmap_event) 


	cpuctx = &get_cpu_var(perf_cpu_context);

	perf_counter_mmap_ctx(&cpuctx->ctx, mmap_event);

	if (cpuctx->task_ctx)

		perf_counter_mmap_ctx(cpuctx->task_ctx, mmap_event);

	put_cpu_var(perf_cpu_context);



	rcu_read_lock();

	/*

	 * doesn't really matter which of the child contexts the

	 * events ends up in.

	 */

	ctx = rcu_dereference(current->perf_counter_ctxp);

	if (ctx)

		perf_counter_mmap_ctx(ctx, mmap_event);

	rcu_read_unlock();



	kfree(buf);

}
@@ -2882,6 +2894,7 @@ static void __perf_swcounter_event(enum perf_event_types type, u32 event, 
{

	struct perf_cpu_context *cpuctx = &get_cpu_var(perf_cpu_context);

	int *recursion = perf_swcounter_recursion_context(cpuctx);

	struct perf_counter_context *ctx;



	if (*recursion)

		goto out;
@@ -2891,10 +2904,15 @@ static void __perf_swcounter_event(enum perf_event_types type, u32 event, 


	perf_swcounter_ctx_event(&cpuctx->ctx, type, event,

				 nr, nmi, regs, addr);

	if (cpuctx->task_ctx) {

		perf_swcounter_ctx_event(cpuctx->task_ctx, type, event,

					 nr, nmi, regs, addr);

	}

	rcu_read_lock();

	/*

	 * doesn't really matter which of the child contexts the

	 * events ends up in.

	 */

	ctx = rcu_dereference(current->perf_counter_ctxp);

	if (ctx)

		perf_swcounter_ctx_event(ctx, type, event, nr, nmi, regs, addr);

	rcu_read_unlock();



	barrier();

	(*recursion)--;