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Commit 2ebd4ffb authored by Matt Helsley's avatar Matt Helsley Committed by Ingo Molnar
Browse files

perf events: Split out task search into helper 



Split out the code which searches for non-exiting tasks into its own
helper. Creating this helper not only makes the code slightly more
readable it prepares to move the search out of find_get_context() in
a subsequent commit.

Signed-off-by: default avatarMatt Helsley <matthltc@us.ibm.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Robin Green <greenrd@greenrd.org>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
LKML-Reference: <561205417b450b8a4bf7488374541d64b4690431.1284407762.git.matthltc@us.ibm.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent d958077d

kernel/perf_event.c

+40 −23
Original line number Diff line number Diff line
@@ -2015,6 +2015,43 @@ alloc_perf_context(struct pmu *pmu, struct task_struct *task) 
	return ctx;

}



static struct task_struct *

find_lively_task_by_vpid(pid_t vpid)

{

	struct task_struct *task;

	int err;



	rcu_read_lock();

	if (!vpid)

		task = current;

	else

		task = find_task_by_vpid(vpid);

	if (task)

		get_task_struct(task);

	rcu_read_unlock();



	if (!task)

		return ERR_PTR(-ESRCH);



	/*

	 * Can't attach events to a dying task.

	 */

	err = -ESRCH;

	if (task->flags & PF_EXITING)

		goto errout;



	/* Reuse ptrace permission checks for now. */

	err = -EACCES;

	if (!ptrace_may_access(task, PTRACE_MODE_READ))

		goto errout;



	return task;

errout:

	put_task_struct(task);

	return ERR_PTR(err);



}



static struct perf_event_context *

find_get_context(struct pmu *pmu, pid_t pid, int cpu)

{
@@ -2047,29 +2084,9 @@ find_get_context(struct pmu *pmu, pid_t pid, int cpu) 
		return ctx;

	}



	rcu_read_lock();

	if (!pid)

		task = current;

	else

		task = find_task_by_vpid(pid);

	if (task)

		get_task_struct(task);

	rcu_read_unlock();



	if (!task)

		return ERR_PTR(-ESRCH);



	/*

	 * Can't attach events to a dying task.

	 */

	err = -ESRCH;

	if (task->flags & PF_EXITING)

		goto errout;



	/* Reuse ptrace permission checks for now. */

	err = -EACCES;

	if (!ptrace_may_access(task, PTRACE_MODE_READ))

		goto errout;

	task = find_lively_task_by_vpid(pid);

	if (IS_ERR(task))

		return (void*)task;



	err = -EINVAL;

	ctxn = pmu->task_ctx_nr;