[tip:perf/core] perf: Fix task refcount bugs

[tip-bot for Peter Zijlstra <a.p.zijlstra@chello.nl>]

Commit-ID:  e7d0bc047548d76feee6b23f7d3d9da927189a50
Gitweb:     http://git.kernel.org/tip/e7d0bc047548d76feee6b23f7d3d9da927189a50
Author:     Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Thu, 14 Oct 2010 16:54:51 +0200
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Mon, 18 Oct 2010 19:58:52 +0200

perf: Fix task refcount bugs

Currently it looks like find_lively_task_by_vpid() takes a task ref
and relies on find_get_context() to drop it.

The problem is that perf_event_create_kernel_counter() shouldn't be
dropping task refs.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Matt Helsley <matthltc@us.ibm.com>
LKML-Reference: <20101014203625.278436085@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 kernel/perf_event.c |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 346dc0e..f928878 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -2190,11 +2190,9 @@ retry:
 		}
 	}
 
-	put_task_struct(task);
 	return ctx;
 
 errout:
-	put_task_struct(task);
 	return ERR_PTR(err);
 }
 
@@ -5602,7 +5600,7 @@ SYSCALL_DEFINE5(perf_event_open,
 	ctx = find_get_context(pmu, task, cpu);
 	if (IS_ERR(ctx)) {
 		err = PTR_ERR(ctx);
-		goto err_group_fd;
+		goto err_task;
 	}
 
 	/*
@@ -5698,6 +5696,9 @@ SYSCALL_DEFINE5(perf_event_open,
 
 err_context:
 	put_ctx(ctx);
+err_task:
+	if (task)
+		put_task_struct(task);
 err_group_fd:
 	fput_light(group_file, fput_needed);
 	free_event(event);