From: Michael Petlan <mpetlan@redhat.com>
To: acme@redhat.com, linux-perf-users@vger.kernel.org
Cc: jolsa@redhat.com
Subject: [PATCH] perf trace: Fix race in signal handling
Date: Tue, 2 Mar 2021 15:41:20 +0100 [thread overview]
Message-ID: <20210302144120.17362-1-mpetlan@redhat.com> (raw)
Since a lot of stuff happens before the SIGINT signal handler is registered
(scanning /proc/*, etc.), on bigger systems, such as Cavium Sabre CN99xx,
it may happen that first interrupt signal is lost and perf isn't correctly
terminated.
The reproduction code might look like the following:
perf trace -a &
PERF_PID=$!
sleep 4
kill -INT $PERF_PID
The issue has been found on a CN99xx machine with RHEL-8 and the patch fixes
it by registering the signal handlers earlier in the init stage.
Suggested-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Michael Petlan <mpetlan@redhat.com>
Tested-by: Michael Petlan <mpetlan@redhat.com>
---
tools/perf/builtin-trace.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 85b6a46e85b6..7ec18ff57fc4 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -3964,9 +3964,6 @@ static int trace__run(struct trace *trace, int argc, const char **argv)
evlist__config(evlist, &trace->opts, &callchain_param);
- signal(SIGCHLD, sig_handler);
- signal(SIGINT, sig_handler);
-
if (forks) {
err = evlist__prepare_workload(evlist, &trace->opts.target, argv, false, NULL);
if (err < 0) {
@@ -4827,6 +4824,8 @@ int cmd_trace(int argc, const char **argv)
signal(SIGSEGV, sighandler_dump_stack);
signal(SIGFPE, sighandler_dump_stack);
+ signal(SIGCHLD, sig_handler);
+ signal(SIGINT, sig_handler);
trace.evlist = evlist__new();
trace.sctbl = syscalltbl__new();
--
2.18.4
next reply other threads:[~2021-03-03 5:14 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-02 14:41 Michael Petlan [this message]
2021-03-05 17:16 ` [PATCH] perf trace: Fix race in signal handling Arnaldo Carvalho de Melo
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