linux_dsm_epyc7002/tools/perf/util/cloexec.c
Adrian Hunter 48536c9195 perf tools: Fix probing for PERF_FLAG_FD_CLOEXEC flag
Commit f6edb53c49 converted the probe to
a CPU wide event first (pid == -1). For kernels that do not support
the PERF_FLAG_FD_CLOEXEC flag the probe fails with EINVAL. Since this
errno is not handled pid is not reset to 0 and the subsequent use of
pid = -1 as an argument brings in an additional failure path if
perf_event_paranoid > 0:

$ perf record -- sleep 1
perf_event_open(..., 0) failed unexpectedly with error 13 (Permission denied)
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.007 MB /tmp/perf.data (11 samples) ]

Also, ensure the fd of the confirmation check is closed and comment why
pid = -1 is used.

Needs to go to 3.18 stable tree as well.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Based-on-patch-by: David Ahern <david.ahern@oracle.com>
Acked-by: David Ahern <david.ahern@oracle.com>
Cc: David Ahern <dsahern@gmail.com>
Link: http://lkml.kernel.org/r/54EC610C.8000403@intel.com
Cc: stable@vger.kernel.org  # v3.18+
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2015-02-25 16:40:13 -03:00

87 lines
1.7 KiB
C

#include <sched.h>
#include "util.h"
#include "../perf.h"
#include "cloexec.h"
#include "asm/bug.h"
#include "debug.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_TYPE_SOFTWARE,
.config = PERF_COUNT_SW_CPU_CLOCK,
.exclude_kernel = 1,
};
int fd;
int err;
int cpu;
pid_t pid = -1;
char sbuf[STRERR_BUFSIZE];
cpu = sched_getcpu();
if (cpu < 0)
cpu = 0;
/*
* Using -1 for the pid is a workaround to avoid gratuitous jump label
* changes.
*/
while (1) {
/* check cloexec flag */
fd = sys_perf_event_open(&attr, pid, cpu, -1,
PERF_FLAG_FD_CLOEXEC);
if (fd < 0 && pid == -1 && errno == EACCES) {
pid = 0;
continue;
}
break;
}
err = errno;
if (fd >= 0) {
close(fd);
return 1;
}
WARN_ONCE(err != EINVAL && err != EBUSY,
"perf_event_open(..., PERF_FLAG_FD_CLOEXEC) failed with unexpected error %d (%s)\n",
err, strerror_r(err, sbuf, sizeof(sbuf)));
/* not supported, confirm error related to PERF_FLAG_FD_CLOEXEC */
while (1) {
fd = sys_perf_event_open(&attr, pid, cpu, -1, 0);
if (fd < 0 && pid == -1 && errno == EACCES) {
pid = 0;
continue;
}
break;
}
err = errno;
if (fd >= 0)
close(fd);
if (WARN_ONCE(fd < 0 && err != EBUSY,
"perf_event_open(..., 0) failed unexpectedly with error %d (%s)\n",
err, strerror_r(err, sbuf, sizeof(sbuf))))
return -1;
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;
}