Messages in this thread Patch in this message | | | Date | Tue, 16 Aug 2022 15:24:11 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH 1/1] tracing: fix a WARN from trace_event_dyn_put_ref |
| |
On Tue, 16 Aug 2022 11:54:18 -0700 Krister Johansen <kjlx@templeofstupid.com> wrote:
> What do you think, would either of these be a solution that you would > find acceptable?
Actually, I think the issue is that the unreg() calls trace_event_put_ref() but the reg() does not do the try_get_ref(), but the perf_trace_init() does. Which is the broken symmetry.
I think if we pull out the trace_event_put_ref() from the unreg() function, we fix the bug and also put back the symmetry.
Does this patch work?
[ Untested, and not even compiled ]
-- Steve
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c index a114549720d6..61e3a2620fa3 100644 --- a/kernel/trace/trace_event_perf.c +++ b/kernel/trace/trace_event_perf.c @@ -157,7 +157,7 @@ static void perf_trace_event_unreg(struct perf_event *p_event) int i; if (--tp_event->perf_refcount > 0) - goto out; + return; tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL); @@ -176,8 +176,6 @@ static void perf_trace_event_unreg(struct perf_event *p_event) perf_trace_buf[i] = NULL; } } -out: - trace_event_put_ref(tp_event); } static int perf_trace_event_open(struct perf_event *p_event) @@ -241,6 +239,7 @@ void perf_trace_destroy(struct perf_event *p_event) mutex_lock(&event_mutex); perf_trace_event_close(p_event); perf_trace_event_unreg(p_event); + trace_event_put_ref(p_event->tp_event); mutex_unlock(&event_mutex); } @@ -292,6 +291,7 @@ void perf_kprobe_destroy(struct perf_event *p_event) mutex_lock(&event_mutex); perf_trace_event_close(p_event); perf_trace_event_unreg(p_event); + trace_event_put_ref(p_event->tp_event); mutex_unlock(&event_mutex); destroy_local_trace_kprobe(p_event->tp_event); @@ -347,6 +347,7 @@ void perf_uprobe_destroy(struct perf_event *p_event) mutex_lock(&event_mutex); perf_trace_event_close(p_event); perf_trace_event_unreg(p_event); + trace_event_put_ref(p_event->tp_event); mutex_unlock(&event_mutex); destroy_local_trace_uprobe(p_event->tp_event); }
| |