SO_ZEROCOPY should return -EOPNOTSUPP rather than -ENOTSUPP

ENOTSUPP is documented as "should never be seen by user programs",
and thus not exposed in <errno.h>, and thus applications cannot safely
check against it (they get "Unknown error 524" as strerror). We should
rather return the well-known -EOPNOTSUPP.

This is similar to 2230a7ef5198 ("drop_monitor: Use correct error
code") and 4a5cdc604b9c ("net/tls: Fix return values to avoid
ENOTSUPP"), which did not seem to cause problems.

Signed-off-by: Samuel Thibault <samuel.thibault@labri.fr>
Acked-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20220307223126.djzvg44v2o2jkjsx@begin
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/core/sock.c b/net/core/sock.c
index 784c92eaded89fdb55be0ad11dd2dadc8548814b..1180a0cb01104561befa1f96deb71f36efcf12da 100644 (file)
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1377,9 +1377,9 @@ set_sndbuf:
                        if (!(sk_is_tcp(sk) ||
                              (sk->sk_type == SOCK_DGRAM &&
                               sk->sk_protocol == IPPROTO_UDP)))
-                               ret = -ENOTSUPP;
+                               ret = -EOPNOTSUPP;
                } else if (sk->sk_family != PF_RDS) {
-                       ret = -ENOTSUPP;
+                       ret = -EOPNOTSUPP;
                }
                if (!ret) {
                        if (val < 0 || val > 1)