Messages in this thread | | | Date | Thu, 31 Mar 2022 20:01:52 -0700 | Subject | Re: [PATCH] sample: bpf: syscall_tp_user: print result of verify_map | From | Yonghong Song <> |
| |
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@189.cn> > --- > 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]);
| |