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authorIan Rogers <irogers@google.com>2022-10-23 18:10:24 -0700
committerArnaldo Carvalho de Melo <acme@redhat.com>2022-10-25 17:40:48 -0300
commit304f0a2f6a6d9336fb5e474d7f62b8677d5ee167 (patch)
tree4fe68aa11c0fcd3a403c75d0b25782d905535db3 /tools
parentf1bdebbb67bd21d7c5dfc42f313f2f54002440b8 (diff)
perf record: Fix event fd races
The write call may set errno which is problematic if occurring in a function also setting errno. Save and restore errno around the write call. done_fd may be used after close, clear it as part of the close and check its validity in the signal handler. Suggested-by: <gthelen@google.com> Reviewed-by: Leo Yan <leo.yan@linaro.org> Signed-off-by: Ian Rogers <irogers@google.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Anand K Mistry <amistry@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Link: https://lore.kernel.org/r/20221024011024.462518-1-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
-rw-r--r--tools/perf/builtin-record.c41
1 files changed, 25 insertions, 16 deletions
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 52d254b1530c..e128b855ddde 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -649,7 +649,7 @@ static int record__pushfn(struct mmap *map, void *to, void *bf, size_t size)
static volatile int signr = -1;
static volatile int child_finished;
#ifdef HAVE_EVENTFD_SUPPORT
-static int done_fd = -1;
+static volatile int done_fd = -1;
#endif
static void sig_handler(int sig)
@@ -661,19 +661,24 @@ static void sig_handler(int sig)
done = 1;
#ifdef HAVE_EVENTFD_SUPPORT
-{
- u64 tmp = 1;
- /*
- * It is possible for this signal handler to run after done is checked
- * in the main loop, but before the perf counter fds are polled. If this
- * happens, the poll() will continue to wait even though done is set,
- * and will only break out if either another signal is received, or the
- * counters are ready for read. To ensure the poll() doesn't sleep when
- * done is set, use an eventfd (done_fd) to wake up the poll().
- */
- if (write(done_fd, &tmp, sizeof(tmp)) < 0)
- pr_err("failed to signal wakeup fd, error: %m\n");
-}
+ if (done_fd >= 0) {
+ u64 tmp = 1;
+ int orig_errno = errno;
+
+ /*
+ * It is possible for this signal handler to run after done is
+ * checked in the main loop, but before the perf counter fds are
+ * polled. If this happens, the poll() will continue to wait
+ * even though done is set, and will only break out if either
+ * another signal is received, or the counters are ready for
+ * read. To ensure the poll() doesn't sleep when done is set,
+ * use an eventfd (done_fd) to wake up the poll().
+ */
+ if (write(done_fd, &tmp, sizeof(tmp)) < 0)
+ pr_err("failed to signal wakeup fd, error: %m\n");
+
+ errno = orig_errno;
+ }
#endif // HAVE_EVENTFD_SUPPORT
}
@@ -2834,8 +2839,12 @@ out_free_threads:
out_delete_session:
#ifdef HAVE_EVENTFD_SUPPORT
- if (done_fd >= 0)
- close(done_fd);
+ if (done_fd >= 0) {
+ fd = done_fd;
+ done_fd = -1;
+
+ close(fd);
+ }
#endif
zstd_fini(&session->zstd_data);
perf_session__delete(session);