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authorYann Droneaud <ydroneaud@opteya.com>2014-06-30 22:28:47 +0200
committerJiri Olsa <jolsa@kernel.org>2014-07-18 09:09:34 +0200
commit57480d2cd93579d665e57e144e1e63f7f02ef058 (patch)
treea1c628c2bd65a943461479ad52cd4bec179e51d7 /tools/perf/util/cloexec.c
parentMerge tag 'perf-core-for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/... (diff)
downloadlinux-57480d2cd93579d665e57e144e1e63f7f02ef058.tar.xz
linux-57480d2cd93579d665e57e144e1e63f7f02ef058.zip
perf tools: Enable close-on-exec flag on perf file descriptor
In commit a21b0b354d4a ('perf: Introduce a flag to enable close-on-exec in perf_event_open()'), flag PERF_FLAG_FD_CLOEXEC was added to perf_event_open(2) syscall to allows userspace to atomically enable close-on-exec behavor when creating the file descriptor. This patch makes perf tools use the new flag if supported by the kernel, so that the event file descriptors got automatically closed if perf tool exec a sub-command. Signed-off-by: Yann Droneaud <ydroneaud@opteya.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/n/1404160127-7475-1-git-send-email-ydroneaud@opteya.com Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Diffstat (limited to 'tools/perf/util/cloexec.c')
-rw-r--r--tools/perf/util/cloexec.c57
1 files changed, 57 insertions, 0 deletions
diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c
new file mode 100644
index 000000000000..c5d05ec17220
--- /dev/null
+++ b/tools/perf/util/cloexec.c
@@ -0,0 +1,57 @@
+#include "util.h"
+#include "../perf.h"
+#include "cloexec.h"
+#include "asm/bug.h"
+
+static unsigned long flag = PERF_FLAG_FD_CLOEXEC;
+
+static int perf_flag_probe(void)
+{
+ /* use 'safest' configuration as used in perf_evsel__fallback() */
+ struct perf_event_attr attr = {
+ .type = PERF_COUNT_SW_CPU_CLOCK,
+ .config = PERF_COUNT_SW_CPU_CLOCK,
+ };
+ int fd;
+ int err;
+
+ /* check cloexec flag */
+ fd = sys_perf_event_open(&attr, 0, -1, -1,
+ PERF_FLAG_FD_CLOEXEC);
+ err = errno;
+
+ if (fd >= 0) {
+ close(fd);
+ return 1;
+ }
+
+ WARN_ONCE(err != EINVAL,
+ "perf_event_open(..., PERF_FLAG_FD_CLOEXEC) failed with unexpected error %d (%s)\n",
+ err, strerror(err));
+
+ /* not supported, confirm error related to PERF_FLAG_FD_CLOEXEC */
+ fd = sys_perf_event_open(&attr, 0, -1, -1, 0);
+ err = errno;
+
+ if (WARN_ONCE(fd < 0,
+ "perf_event_open(..., 0) failed unexpectedly with error %d (%s)\n",
+ err, strerror(err)))
+ return -1;
+
+ close(fd);
+
+ return 0;
+}
+
+unsigned long perf_event_open_cloexec_flag(void)
+{
+ static bool probed;
+
+ if (!probed) {
+ if (perf_flag_probe() <= 0)
+ flag = 0;
+ probed = true;
+ }
+
+ return flag;
+}