Re: [PATCH bpf-next] selftests/bpf: Add F_SETFL for fcntl

[Geliang Tang <geliang@kernel.org>]

Hi Jakub,
 
On Wed, 2024-04-03 at 15:29 -0700, John Fastabend wrote:
> Jakub Sitnicki wrote:
> > Hi Geliang,
> > 
> > On Wed, Apr 03, 2024 at 04:32 PM +08, Geliang Tang wrote:
> > > From: Geliang Tang <tanggeliang@kylinos.cn>
> > > 
> > > Incorrect arguments are passed to fcntl() in test_sockmap.c when
> > > invoking
> > > it to set file status flags. If O_NONBLOCK is used as 2nd
> > > argument and
> > > passed into fcntl, -EINVAL will be returned (See do_fcntl() in
> > > fs/fcntl.c).
> > > The correct approach is to use F_SETFL as 2nd argument, and
> > > O_NONBLOCK as
> > > 3rd one.
> > > 
> > > Fixes: 16962b2404ac ("bpf: sockmap, add selftests")
> > > Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
> > > ---
> > >  tools/testing/selftests/bpf/test_sockmap.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/tools/testing/selftests/bpf/test_sockmap.c
> > > b/tools/testing/selftests/bpf/test_sockmap.c
> > > index 024a0faafb3b..34d6a1e6f664 100644
> > > --- a/tools/testing/selftests/bpf/test_sockmap.c
> > > +++ b/tools/testing/selftests/bpf/test_sockmap.c
> > > @@ -603,7 +603,7 @@ static int msg_loop(int fd, int iov_count,
> > > int iov_length, int cnt,
> > >  		struct timeval timeout;
> > >  		fd_set w;
> > >  
> > > -		fcntl(fd, fd_flags);
> > > +		fcntl(fd, F_SETFL, fd_flags);
> > >  		/* Account for pop bytes noting each iteration
> > > of apply will
> > >  		 * call msg_pop_data helper so we need to
> > > account for this
> > >  		 * by calculating the number of apply
> > > iterations. Note user
> > 
> > Good catch. But we also need to figure out why some tests failing
> > with
> > this patch applied and fix them in one go:
> > 
> > # 6/ 7  sockmap::txmsg test skb:FAIL
> > #21/ 7 sockhash::txmsg test skb:FAIL
> > #36/ 7 sockhash:ktls:txmsg test skb:FAIL
> > Pass: 42 Fail: 3

Sorry, I didn't notice these fails in my testing before, they do exist.
I'll try to fix them and sent a v2 soon.

Thanks,
-Geliang

> > 
> > I'm seeing this error message when running `test_sockmap`:
> > 
> > detected skb data error with skb ingress update @iov[0]:0 "00 00 00
> > 00" != "PASS"
> > data verify msg failed: Unknown error -5
> > rx thread exited with err 1.
> 
> I have a theory this is a real bug in the SK_SKB_STREAM_PARSER which
> has an
> issue with wakup logic. Maybe we wakeup the poll/select logic before
> the
> data is copied and because the recv() is actually nonblocking now we
> get
> the error.
> 
> > 
> > I'd also:
> > - add an error check for fnctl, so we don't regress,
> > - get rid of fd_flags, pass O_NONBLOCK flag directly to fnctl.
> > 
> > Thanks,
> > -jkbs
> 
>