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authorPeter Zijlstra <peterz@infradead.org>2014-05-21 19:32:19 +0400
committerIngo Molnar <mingo@kernel.org>2014-06-06 09:54:02 +0400
commite041e328c4b41e1db79bfe5ba9992c2ed771ad19 (patch)
tree88f8689160ae586c728e6ef665cc4c580c116ba9
parent22c91aa23547a4363fd2a9ffddde95c899ac8aa0 (diff)
downloadlinux-e041e328c4b41e1db79bfe5ba9992c2ed771ad19.tar.xz
perf: Fix perf_event_comm() vs. exec() assumption
perf_event_comm() assumes that set_task_comm() is only called on exec(), and in particular that its only called on current. Neither are true, as Dave reported a WARN triggered by set_task_comm() being called on !current. Separate the exec() hook from the comm hook. Reported-by: Dave Jones <davej@redhat.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/20140521153219.GH5226@laptop.programming.kicks-ass.net [ Build fix. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--fs/exec.c1
-rw-r--r--include/linux/perf_event.h4
-rw-r--r--kernel/events/core.c28
3 files changed, 20 insertions, 13 deletions
diff --git a/fs/exec.c b/fs/exec.c
index 238b7aa26f68..a038a41a3677 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1110,6 +1110,7 @@ void setup_new_exec(struct linux_binprm * bprm)
else
set_dumpable(current->mm, suid_dumpable);
+ perf_event_exec();
set_task_comm(current, kbasename(bprm->filename));
/* Set the new mm task size. We have to do that late because it may
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 3ef6ea12806a..9b5cd1992a88 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -695,6 +695,7 @@ extern struct perf_guest_info_callbacks *perf_guest_cbs;
extern int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks);
extern int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks);
+extern void perf_event_exec(void);
extern void perf_event_comm(struct task_struct *tsk);
extern void perf_event_fork(struct task_struct *tsk);
@@ -772,7 +773,7 @@ extern void perf_event_enable(struct perf_event *event);
extern void perf_event_disable(struct perf_event *event);
extern int __perf_event_disable(void *info);
extern void perf_event_task_tick(void);
-#else
+#else /* !CONFIG_PERF_EVENTS: */
static inline void
perf_event_task_sched_in(struct task_struct *prev,
struct task_struct *task) { }
@@ -802,6 +803,7 @@ static inline int perf_unregister_guest_info_callbacks
(struct perf_guest_info_callbacks *callbacks) { return 0; }
static inline void perf_event_mmap(struct vm_area_struct *vma) { }
+static inline void perf_event_exec(void) { }
static inline void perf_event_comm(struct task_struct *tsk) { }
static inline void perf_event_fork(struct task_struct *tsk) { }
static inline void perf_event_init(void) { }
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 440eefc67397..647698f91988 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2970,6 +2970,22 @@ out:
local_irq_restore(flags);
}
+void perf_event_exec(void)
+{
+ struct perf_event_context *ctx;
+ int ctxn;
+
+ rcu_read_lock();
+ for_each_task_context_nr(ctxn) {
+ ctx = current->perf_event_ctxp[ctxn];
+ if (!ctx)
+ continue;
+
+ perf_event_enable_on_exec(ctx);
+ }
+ rcu_read_unlock();
+}
+
/*
* Cross CPU call to read the hardware event
*/
@@ -5057,18 +5073,6 @@ static void perf_event_comm_event(struct perf_comm_event *comm_event)
void perf_event_comm(struct task_struct *task)
{
struct perf_comm_event comm_event;
- struct perf_event_context *ctx;
- int ctxn;
-
- rcu_read_lock();
- for_each_task_context_nr(ctxn) {
- ctx = task->perf_event_ctxp[ctxn];
- if (!ctx)
- continue;
-
- perf_event_enable_on_exec(ctx);
- }
- rcu_read_unlock();
if (!atomic_read(&nr_comm_events))
return;