Commit-ID: 515619f209114697fabd21eed1623bfa69746815 Gitweb: http://git.kernel.org/tip/515619f209114697fabd21eed1623bfa69746815 Author: Oleg Nesterov <oleg@xxxxxxxxxx> AuthorDate: Sat, 13 Apr 2013 15:36:49 +0200 Committer: Oleg Nesterov <oleg@xxxxxxxxxx> CommitDate: Mon, 15 Apr 2013 17:39:52 +0200 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@xxxxxxxxxx> --- kernel/trace/trace_uprobe.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c index 37ccb72..32494fb0 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(); -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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