2015-08-12 09:38:24

by xiakaixu

Subject: [PATCH net-next] bpf: fix build warnings and add function read_trace_pipe()

There are two improvements in this patch:
1. Fix the build warnings;
2. Add function read_trace_pipe() to print the result on
the screen;

Before this patch, we can get the result through /sys/kernel/de
bug/tracing/trace_pipe and get nothing on the screen.
By applying this patch, the result can be printed on the screen.
$ ./tracex6
...
tracex6-705 [003] d..1 131.428593: : CPU-3 19981414
sshd-683 [000] d..1 131.428727: : CPU-0 221682321
sshd-683 [000] d..1 131.428821: : CPU-0 221808766
sshd-683 [000] d..1 131.428950: : CPU-0 221982984
sshd-683 [000] d..1 131.429045: : CPU-0 222111851
tracex6-705 [003] d..1 131.429168: : CPU-3 20757551
sshd-683 [000] d..1 131.429170: : CPU-0 222281240
sshd-683 [000] d..1 131.429261: : CPU-0 222403340
sshd-683 [000] d..1 131.429378: : CPU-0 222561024
...

Signed-off-by: Kaixu Xia <[email protected]>
---
samples/bpf/tracex6_kern.c | 1 +
samples/bpf/tracex6_user.c | 22 +++++++++++++---------
2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/samples/bpf/tracex6_kern.c b/samples/bpf/tracex6_kern.c
index 23d1cff..be479c4 100644
--- a/samples/bpf/tracex6_kern.c
+++ b/samples/bpf/tracex6_kern.c
@@ -1,3 +1,4 @@
+#include <linux/ptrace.h>
#include <linux/version.h>
#include <uapi/linux/bpf.h>
#include "bpf_helpers.h"
diff --git a/samples/bpf/tracex6_user.c b/samples/bpf/tracex6_user.c
index 928f05e..8ea4976 100644
--- a/samples/bpf/tracex6_user.c
+++ b/samples/bpf/tracex6_user.c
@@ -17,8 +17,7 @@ static void test_bpf_perf_event(void)
{
int nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
int *pmu_fd = malloc(nr_cpus * sizeof(int));
- unsigned long value;
- int i;
+ int status, i;

struct perf_event_attr attr_insn_pmu = {
.freq = 0,
@@ -32,22 +31,26 @@ static void test_bpf_perf_event(void)

for (i = 0; i < nr_cpus; i++) {
pmu_fd[i] = perf_event_open(&attr_insn_pmu, -1/*pid*/, i/*cpu*/, -1/*group_fd*/, 0);
- if (pmu_fd[i] < 0)
+ if (pmu_fd[i] < 0) {
printf("event syscall failed\n");
+ goto exit;
+ }

bpf_update_elem(map_fd[0], &i, &pmu_fd[i], BPF_ANY);
ioctl(pmu_fd[i], PERF_EVENT_IOC_ENABLE, 0);
}

- system("ls");
- system("pwd");
- system("sleep 2");
+ status = system("ls > /dev/null");
+ if (status)
+ goto exit;
+ status = system("sleep 2");
+ if (status)
+ goto exit;

+exit:
for (i = 0; i < nr_cpus; i++)
close(pmu_fd[i]);
-
- close(map_fd);
-
+ close(map_fd[0]);
free(pmu_fd);
}

@@ -63,6 +66,7 @@ int main(int argc, char **argv)
}

test_bpf_perf_event();
+ read_trace_pipe();

return 0;
}
--
1.8.3.4

2015-08-12 16:26:05

by Alexei Starovoitov

Subject: Re: [PATCH net-next] bpf: fix build warnings and add function read_trace_pipe()

On 8/12/15 2:37 AM, Kaixu Xia wrote:
> There are two improvements in this patch:
> 1. Fix the build warnings;
> 2. Add function read_trace_pipe() to print the result on
> the screen;
>
> Before this patch, we can get the result through /sys/kernel/de
> bug/tracing/trace_pipe and get nothing on the screen.
> By applying this patch, the result can be printed on the screen.
> $ ./tracex6
> ...
> tracex6-705 [003] d..1 131.428593: : CPU-3 19981414
> sshd-683 [000] d..1 131.428727: : CPU-0 221682321
> sshd-683 [000] d..1 131.428821: : CPU-0 221808766
> sshd-683 [000] d..1 131.428950: : CPU-0 221982984
> sshd-683 [000] d..1 131.429045: : CPU-0 222111851
> tracex6-705 [003] d..1 131.429168: : CPU-3 20757551
> sshd-683 [000] d..1 131.429170: : CPU-0 222281240
> sshd-683 [000] d..1 131.429261: : CPU-0 222403340
> sshd-683 [000] d..1 131.429378: : CPU-0 222561024
> ...
>
> Signed-off-by: Kaixu Xia<[email protected]>

thanks!
Acked-by: Alexei Starovoitov <[email protected]>

2015-08-12 23:39:28

by David Miller

Subject: Re: [PATCH net-next] bpf: fix build warnings and add function read_trace_pipe()

From: Kaixu Xia <[email protected]>
Date: Wed, 12 Aug 2015 09:37:53 +0000

> There are two improvements in this patch:
> 1. Fix the build warnings;
> 2. Add function read_trace_pipe() to print the result on
> the screen;
>
> Before this patch, we can get the result through /sys/kernel/de
> bug/tracing/trace_pipe and get nothing on the screen.
> By applying this patch, the result can be printed on the screen.
> $ ./tracex6
> ...
> tracex6-705 [003] d..1 131.428593: : CPU-3 19981414
> sshd-683 [000] d..1 131.428727: : CPU-0 221682321
> sshd-683 [000] d..1 131.428821: : CPU-0 221808766
> sshd-683 [000] d..1 131.428950: : CPU-0 221982984
> sshd-683 [000] d..1 131.429045: : CPU-0 222111851
> tracex6-705 [003] d..1 131.429168: : CPU-3 20757551
> sshd-683 [000] d..1 131.429170: : CPU-0 222281240
> sshd-683 [000] d..1 131.429261: : CPU-0 222403340
> sshd-683 [000] d..1 131.429378: : CPU-0 222561024
> ...
>
> Signed-off-by: Kaixu Xia <[email protected]>

Applied, thanks.