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authorOleg Nesterov <oleg@redhat.com>2013-04-13 15:36:49 +0200
committerOleg Nesterov <oleg@redhat.com>2013-04-15 17:39:52 +0200
commit515619f209114697fabd21eed1623bfa69746815 (patch)
tree84655a5404fb290f8492f3f953f9e61007f7c3e2 /kernel/trace
parent32520b2c695b23221751eb09360a6a3dd3105b52 (diff)
uprobes/perf: Avoid perf_trace_buf_prepare/submit if ->perf_events is empty
perf_trace_buf_prepare() + perf_trace_buf_submit() make no sense if this task/CPU has no active counters. Change uprobe_perf_print() to return if hlist_empty(call->perf_events). Note: this is not uprobe-specific, we can change other users too. Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/trace_uprobe.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 37ccb72f0f3b..32494fb0ee64 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -820,6 +820,10 @@ static void uprobe_perf_print(struct trace_uprobe *tu,
return;
preempt_disable();
+ head = this_cpu_ptr(call->perf_events);
+ if (hlist_empty(head))
+ goto out;
+
entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
if (!entry)
goto out;
@@ -836,7 +840,6 @@ static void uprobe_perf_print(struct trace_uprobe *tu,
for (i = 0; i < tu->nr_args; i++)
call_fetch(&tu->args[i].fetch, regs, data + tu->args[i].offset);
- head = this_cpu_ptr(call->perf_events);
perf_trace_buf_submit(entry, size, rctx, 0, 1, regs, head, NULL);
out:
preempt_enable();