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| author | Taeung Song <treeze.taeung@gmail.com> | 2018-07-04 22:36:37 +0900 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2018-07-05 09:58:52 +0200 |
| commit | 492b7e894587c151be681f86d4d1d086375f7b45 (patch) | |
| tree | 20f39b54a83769caa0867f5898ef4521b21d16d5 /samples | |
| parent | 4d5d33a085335ef469c9a87792bcaaaa8e64d8c4 (diff) | |
| download | linux-492b7e894587c151be681f86d4d1d086375f7b45.tar.bz2 | |
samples/bpf: Check the result of system()
To avoid the below build warning message,
use new generate_load() checking the return value.
ignoring return value of ‘system’, declared with attribute warn_unused_result
And it also refactors the duplicate code of both
test_perf_event_all_cpu() and test_perf_event_task()
Cc: Teng Qin <qinteng@fb.com>
Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'samples')
| -rw-r--r-- | samples/bpf/trace_event_user.c | 27 |
1 files changed, 24 insertions, 3 deletions
diff --git a/samples/bpf/trace_event_user.c b/samples/bpf/trace_event_user.c index 1fa1becfa641..d08046ab81f0 100644 --- a/samples/bpf/trace_event_user.c +++ b/samples/bpf/trace_event_user.c @@ -122,6 +122,16 @@ static void print_stacks(void) } } +static inline int generate_load(void) +{ + if (system("dd if=/dev/zero of=/dev/null count=5000k status=none") < 0) { + printf("failed to generate some load with dd: %s\n", strerror(errno)); + return -1; + } + + return 0; +} + static void test_perf_event_all_cpu(struct perf_event_attr *attr) { int nr_cpus = sysconf(_SC_NPROCESSORS_CONF); @@ -142,7 +152,11 @@ static void test_perf_event_all_cpu(struct perf_event_attr *attr) assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_SET_BPF, prog_fd[0]) == 0); assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_ENABLE) == 0); } - system("dd if=/dev/zero of=/dev/null count=5000k status=none"); + + if (generate_load() < 0) { + error = 1; + goto all_cpu_err; + } print_stacks(); all_cpu_err: for (i--; i >= 0; i--) { @@ -156,7 +170,7 @@ all_cpu_err: static void test_perf_event_task(struct perf_event_attr *attr) { - int pmu_fd; + int pmu_fd, error = 0; /* per task perf event, enable inherit so the "dd ..." command can be traced properly. * Enabling inherit will cause bpf_perf_prog_read_time helper failure. @@ -171,10 +185,17 @@ static void test_perf_event_task(struct perf_event_attr *attr) } assert(ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd[0]) == 0); assert(ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE) == 0); - system("dd if=/dev/zero of=/dev/null count=5000k status=none"); + + if (generate_load() < 0) { + error = 1; + goto err; + } print_stacks(); +err: ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE); close(pmu_fd); + if (error) + int_exit(0); } static void test_bpf_perf_event(void) |