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samples/bpf: Check the result of system()

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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>
This commit is contained in:
Taeung Song 2018-07-04 22:36:37 +09:00 committed by Daniel Borkmann
parent 4d5d33a085
commit 492b7e8945
1 changed files with 24 additions and 3 deletions
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27
samples/bpf/trace_event_user.c
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@ -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) static void test_perf_event_all_cpu(struct perf_event_attr *attr)
{ {
int nr_cpus = sysconf(_SC_NPROCESSORS_CONF); 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_SET_BPF, prog_fd[0]) == 0);
assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_ENABLE) == 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(); print_stacks();
all_cpu_err: all_cpu_err:
for (i--; i >= 0; i--) { for (i--; i >= 0; i--) {
@ -156,7 +170,7 @@ static void test_perf_event_all_cpu(struct perf_event_attr *attr)
static void test_perf_event_task(struct perf_event_attr *attr) 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. /* 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. * 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_SET_BPF, prog_fd[0]) == 0);
assert(ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE) == 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(); print_stacks();
err:
ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE); ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE);
close(pmu_fd); close(pmu_fd);
if (error)
int_exit(0);
} }
static void test_bpf_perf_event(void) static void test_bpf_perf_event(void)