On 3/31/22 6:41 PM, Song Chen wrote:
syscall_tp only prints the map id and messages when something goes wrong,
but it doesn't print the value passed from bpf map. I think it's better
to show that value to users.
What's more, i also added a 2-second sleep before calling verify_map,
to make the value more obvious.
Signed-off-by: Song Chen <chensong_2000@xxxxxx>
---
samples/bpf/syscall_tp_user.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/samples/bpf/syscall_tp_user.c b/samples/bpf/syscall_tp_user.c
index a0ebf1833ed3..1faa7f08054e 100644
--- a/samples/bpf/syscall_tp_user.c
+++ b/samples/bpf/syscall_tp_user.c
@@ -36,6 +36,9 @@ static void verify_map(int map_id)
fprintf(stderr, "failed: map #%d returns value 0\n", map_id);
return;
}
+
+ printf("verify map:%d val: %d\n", map_id, val);
I am not sure how useful it is or anybody really cares.
This is just a sample to demonstrate how bpf tracepoint works.
The error path has error print out already.
+
val = 0;
if (bpf_map_update_elem(map_id, &key, &val, BPF_ANY) != 0) {
fprintf(stderr, "map_update failed: %s\n", strerror(errno));
@@ -98,6 +101,7 @@ static int test(char *filename, int num_progs)
}
close(fd);
+ sleep(2);
The commit message mentioned this sleep(2) is
to make the value more obvious. I don't know what does this mean.
sleep(2) can be added only if it fixed a bug.
/* verify the map */
for (i = 0; i < num_progs; i++) {
verify_map(map0_fds[i]);
