| Message ID | 1648777272-21473-1-git-send-email-chensong_2000@189.cn (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | BPF |
| Headers | show |
| Series | sample: bpf: syscall_tp_user: print result of verify_map | expand |
| Context | Check | Description |
|---|---|---|
| bpf/vmtest-bpf-next-PR | fail | PR summary |
| netdev/tree_selection | success | Not a local patch |
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]);
在 2022/4/1 11:01, Yonghong Song 写道: > > > 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. The value in bpf map means how many times trace_enter_open_at are triggered with tracepoint,sys_enter_openat. Sleep(2) is to enlarge the result, tell the user how many files are opened in the last 2 seconds. It shows like this: sudo ./samples/bpf/syscall_tp prog #0: map ids 4 5 verify map:4 val: 253 verify map:5 val: 252 If we work harder, we can also print those files' name and opened by which process. It's just an improvement instead of a bug fix, i will drop it if reviewers think it's unnecessary. Thanks. BR chensong > >> /* verify the map */ >> for (i = 0; i < num_progs; i++) { >> verify_map(map0_fds[i]); >
On 3/31/22 8:37 PM, Song Chen wrote: > > > 在 2022/4/1 11:01, Yonghong Song 写道: >> >> >> 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. Considering we already have printf("prog #%d: map ids %d %d\n", i, map0_fds[i], map1_fds[i]); I think your proposed additional printout printf("verify map:%d val: %d\n", map_id, val); might be okay. The commit message should be rewritten to justify this change something like: we already print out prog <some number>: map ids <..> <...> further print out verify map: ... will help user to understand the program runs successfully. I think sleep(2) is unnecessary. >> >>> + >>> 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. > > The value in bpf map means how many times trace_enter_open_at are > triggered with tracepoint,sys_enter_openat. Sleep(2) is to enlarge the > result, tell the user how many files are opened in the last 2 seconds. > > It shows like this: > > sudo ./samples/bpf/syscall_tp > prog #0: map ids 4 5 > verify map:4 val: 253 > verify map:5 val: 252 > > If we work harder, we can also print those files' name and opened by > which process. > > It's just an improvement instead of a bug fix, i will drop it if > reviewers think it's unnecessary. > > Thanks. > > BR > > chensong >> >>> /* verify the map */ >>> for (i = 0; i < num_progs; i++) { >>> verify_map(map0_fds[i]); >>
Hi, 在 2022/4/2 00:28, Yonghong Song 写道: > > > On 3/31/22 8:37 PM, Song Chen wrote: >> >> >> 在 2022/4/1 11:01, Yonghong Song 写道: >>> >>> >>> 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. > > Considering we already have > printf("prog #%d: map ids %d %d\n", i, map0_fds[i], map1_fds[i]); > I think your proposed additional printout > printf("verify map:%d val: %d\n", map_id, val); > might be okay. The commit message should be rewritten > to justify this change something like: > we already print out > prog <some number>: map ids <..> <...> > further print out > verify map: ... > will help user to understand the program runs successfully. > > I think sleep(2) is unnecessary. will do, many thanks. BR Song > >>> >>>> + >>>> 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. >> >> The value in bpf map means how many times trace_enter_open_at are >> triggered with tracepoint,sys_enter_openat. Sleep(2) is to enlarge the >> result, tell the user how many files are opened in the last 2 seconds. >> >> It shows like this: >> >> sudo ./samples/bpf/syscall_tp >> prog #0: map ids 4 5 >> verify map:4 val: 253 >> verify map:5 val: 252 >> >> If we work harder, we can also print those files' name and opened by >> which process. >> >> It's just an improvement instead of a bug fix, i will drop it if >> reviewers think it's unnecessary. >> >> Thanks. >> >> BR >> >> chensong >>> >>>> /* verify the map */ >>>> for (i = 0; i < num_progs; i++) { >>>> verify_map(map0_fds[i]); >>> >
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); + 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); /* verify the map */ for (i = 0; i < num_progs; i++) { verify_map(map0_fds[i]);
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(+)