| Message ID | 20221013200922.17167-1-gerhard@engleder-embedded.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 05ee658c654bacda03f7fecef367e62aaf8e1cfe |
| Delegated to: | BPF |
| Headers | show |
| Series | [net-next] samples/bpf: Fix map interation in xdp1_user | expand |
On Thu, Oct 13, 2022 at 2:01 PM Gerhard Engleder <gerhard@engleder-embedded.com> wrote: > > BPF map iteration in xdp1_user results in endless loop without any > output, because the return value of bpf_map_get_next_key() is checked > against the wrong value. > > Other call locations of bpf_map_get_next_key() check for equal 0 for > continuing the iteration. xdp1_user checks against unequal -1. This is > wrong for a function which can return arbitrary negative errno values, > because a return value of e.g. -2 results in an endless loop. > > With this fix xdp1_user is printing statistics again: > proto 0: 1 pkt/s > proto 0: 1 pkt/s > proto 17: 107383 pkt/s > proto 17: 881655 pkt/s > proto 17: 882083 pkt/s > proto 17: 881758 pkt/s > > Signed-off-by: Gerhard Engleder <gerhard@engleder-embedded.com> Acked-by: Song Liu <song@kernel.org> > --- > samples/bpf/xdp1_user.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/samples/bpf/xdp1_user.c b/samples/bpf/xdp1_user.c > index ac370e638fa3..281dc964de8d 100644 > --- a/samples/bpf/xdp1_user.c > +++ b/samples/bpf/xdp1_user.c > @@ -51,7 +51,7 @@ static void poll_stats(int map_fd, int interval) > > sleep(interval); > > - while (bpf_map_get_next_key(map_fd, &key, &key) != -1) { > + while (bpf_map_get_next_key(map_fd, &key, &key) == 0) { > __u64 sum = 0; > > assert(bpf_map_lookup_elem(map_fd, &key, values) == 0); > -- > 2.30.2 >
Hello: This patch was applied to bpf/bpf-next.git (master) by Martin KaFai Lau <martin.lau@kernel.org>: On Thu, 13 Oct 2022 22:09:22 +0200 you wrote: > BPF map iteration in xdp1_user results in endless loop without any > output, because the return value of bpf_map_get_next_key() is checked > against the wrong value. > > Other call locations of bpf_map_get_next_key() check for equal 0 for > continuing the iteration. xdp1_user checks against unequal -1. This is > wrong for a function which can return arbitrary negative errno values, > because a return value of e.g. -2 results in an endless loop. > > [...] Here is the summary with links: - [net-next] samples/bpf: Fix map interation in xdp1_user https://git.kernel.org/bpf/bpf-next/c/05ee658c654b You are awesome, thank you!
diff --git a/samples/bpf/xdp1_user.c b/samples/bpf/xdp1_user.c index ac370e638fa3..281dc964de8d 100644 --- a/samples/bpf/xdp1_user.c +++ b/samples/bpf/xdp1_user.c @@ -51,7 +51,7 @@ static void poll_stats(int map_fd, int interval) sleep(interval); - while (bpf_map_get_next_key(map_fd, &key, &key) != -1) { + while (bpf_map_get_next_key(map_fd, &key, &key) == 0) { __u64 sum = 0; assert(bpf_map_lookup_elem(map_fd, &key, values) == 0);
BPF map iteration in xdp1_user results in endless loop without any output, because the return value of bpf_map_get_next_key() is checked against the wrong value. Other call locations of bpf_map_get_next_key() check for equal 0 for continuing the iteration. xdp1_user checks against unequal -1. This is wrong for a function which can return arbitrary negative errno values, because a return value of e.g. -2 results in an endless loop. With this fix xdp1_user is printing statistics again: proto 0: 1 pkt/s proto 0: 1 pkt/s proto 17: 107383 pkt/s proto 17: 881655 pkt/s proto 17: 882083 pkt/s proto 17: 881758 pkt/s Signed-off-by: Gerhard Engleder <gerhard@engleder-embedded.com> --- samples/bpf/xdp1_user.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)