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Commit 492b7e89 authored by Taeung Song's avatar Taeung Song Committed by Daniel Borkmann
Browse files

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: default avatarTaeung Song <treeze.taeung@gmail.com>
Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 4d5d33a0

samples/bpf/trace_event_user.c

+24 −3
Original line number Original line Diff line number Diff line
@@ -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)