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Commit 4af57ef2 authored by Yan, Zheng's avatar Yan, Zheng Committed by Ingo Molnar
Browse files

perf: Add pmu specific data for perf task context 



Introduce a new flag PERF_ATTACH_TASK_DATA for perf event's attach
stata. The flag is set by PMU's event_init() callback, it indicates
that perf event needs PMU specific data.

The PMU specific data are initialized to zeros. Later patches will
use PMU specific data to save LBR stack.

Signed-off-by: default avatarYan, Zheng <zheng.z.yan@intel.com>
Signed-off-by: default avatarKan Liang <kan.liang@intel.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: eranian@google.com
Cc: jolsa@redhat.com
Link: http://lkml.kernel.org/r/1415156173-10035-6-git-send-email-kan.liang@intel.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent e9d7f7cd

include/linux/perf_event.h

+6 −0
Original line number Diff line number Diff line
@@ -271,6 +271,10 @@ struct pmu { 
	 */

	void (*sched_task)		(struct perf_event_context *ctx,

					bool sched_in);

	/*

	 * PMU specific data size

	 */

	size_t				task_ctx_size;



};
@@ -307,6 +311,7 @@ struct swevent_hlist { 
#define PERF_ATTACH_CONTEXT	0x01

#define PERF_ATTACH_GROUP	0x02

#define PERF_ATTACH_TASK	0x04

#define PERF_ATTACH_TASK_DATA	0x08



struct perf_cgroup;

struct ring_buffer;
@@ -511,6 +516,7 @@ struct perf_event_context { 
	u64				generation;

	int				pin_count;

	int				nr_cgroups;	 /* cgroup evts */

	void				*task_ctx_data; /* pmu specific data */

	struct rcu_head			rcu_head;



	struct delayed_work		orphans_remove;

kernel/events/core.c

+36 −4
Original line number Diff line number Diff line
@@ -905,6 +905,15 @@ static void get_ctx(struct perf_event_context *ctx) 
	WARN_ON(!atomic_inc_not_zero(&ctx->refcount));

}



static void free_ctx(struct rcu_head *head)

{

	struct perf_event_context *ctx;



	ctx = container_of(head, struct perf_event_context, rcu_head);

	kfree(ctx->task_ctx_data);

	kfree(ctx);

}



static void put_ctx(struct perf_event_context *ctx)

{

	if (atomic_dec_and_test(&ctx->refcount)) {
@@ -912,7 +921,7 @@ static void put_ctx(struct perf_event_context *ctx) 
			put_ctx(ctx->parent_ctx);

		if (ctx->task)

			put_task_struct(ctx->task);

		kfree_rcu(ctx, rcu_head);

		call_rcu(&ctx->rcu_head, free_ctx);

	}

}
@@ -3309,12 +3318,15 @@ find_lively_task_by_vpid(pid_t vpid) 
 * Returns a matching context with refcount and pincount.

 */

static struct perf_event_context *

find_get_context(struct pmu *pmu, struct task_struct *task, int cpu)

find_get_context(struct pmu *pmu, struct task_struct *task,

		struct perf_event *event)

{

	struct perf_event_context *ctx, *clone_ctx = NULL;

	struct perf_cpu_context *cpuctx;

	void *task_ctx_data = NULL;

	unsigned long flags;

	int ctxn, err;

	int cpu = event->cpu;



	if (!task) {

		/* Must be root to operate on a CPU event: */
@@ -3342,11 +3354,24 @@ find_get_context(struct pmu *pmu, struct task_struct *task, int cpu) 
	if (ctxn < 0)

		goto errout;



	if (event->attach_state & PERF_ATTACH_TASK_DATA) {

		task_ctx_data = kzalloc(pmu->task_ctx_size, GFP_KERNEL);

		if (!task_ctx_data) {

			err = -ENOMEM;

			goto errout;

		}

	}



retry:

	ctx = perf_lock_task_context(task, ctxn, &flags);

	if (ctx) {

		clone_ctx = unclone_ctx(ctx);

		++ctx->pin_count;



		if (task_ctx_data && !ctx->task_ctx_data) {

			ctx->task_ctx_data = task_ctx_data;

			task_ctx_data = NULL;

		}

		raw_spin_unlock_irqrestore(&ctx->lock, flags);



		if (clone_ctx)
@@ -3357,6 +3382,11 @@ find_get_context(struct pmu *pmu, struct task_struct *task, int cpu) 
		if (!ctx)

			goto errout;



		if (task_ctx_data) {

			ctx->task_ctx_data = task_ctx_data;

			task_ctx_data = NULL;

		}



		err = 0;

		mutex_lock(&task->perf_event_mutex);

		/*
@@ -3383,9 +3413,11 @@ find_get_context(struct pmu *pmu, struct task_struct *task, int cpu) 
		}

	}



	kfree(task_ctx_data);

	return ctx;



errout:

	kfree(task_ctx_data);

	return ERR_PTR(err);

}
@@ -7559,7 +7591,7 @@ SYSCALL_DEFINE5(perf_event_open, 
	/*

	 * Get the target context (task or percpu):

	 */

	ctx = find_get_context(pmu, task, event->cpu);

	ctx = find_get_context(pmu, task, event);

	if (IS_ERR(ctx)) {

		err = PTR_ERR(ctx);

		goto err_alloc;
@@ -7765,7 +7797,7 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu, 


	account_event(event);



	ctx = find_get_context(event->pmu, task, cpu);

	ctx = find_get_context(event->pmu, task, event);

	if (IS_ERR(ctx)) {

		err = PTR_ERR(ctx);

		goto err_free;