Commit-ID: e041e328c4b41e1db79bfe5ba9992c2ed771ad19
Gitweb: http://git.kernel.org/tip/e041e328c4b41e1db79bfe5ba9992c2ed771ad19
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Wed, 21 May 2014 17:32:19 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 6 Jun 2014 07:54:02 +0200
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@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: linux-fsdevel@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20140521153219.GH5226@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
[ Build fix. ]
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
fs/exec.c | 1 +
include/linux/perf_event.h | 4 +++-
kernel/events/core.c | 28 ++++++++++++++++------------
3 files changed, 20 insertions(+), 13 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c
index 238b7aa..a038a41 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 3ef6ea1..9b5cd19 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 440eefc..647698f 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;
--
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