net/smc: retain old name for diag_mode field

Commit c601171d7a60 ("net/smc: provide smc mode in smc_diag.c") changed
the name of diag_fallback field of struct smc_diag_msg structure
to diag_mode.  However, this structure is a part of UAPI, and this change
breaks user space applications that use it ([1], for example).  Since
the new name is more suitable, convert the field to a union that provides
access to the data via both the new and the old name.

[1] https://gitlab.com/strace/strace/blob/v4.24/netlink_smc_diag.c#L165

Fixes: c601171d7a60 ("net/smc: provide smc mode in smc_diag.c")
Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/uapi/linux/smc_diag.h b/include/uapi/linux/smc_diag.h
index 6180c6d..8cb3a6f 100644 (file)
--- a/include/uapi/linux/smc_diag.h
+++ b/include/uapi/linux/smc_diag.h
@@ -20,7 +20,10 @@ struct smc_diag_req {
 struct smc_diag_msg {
        __u8            diag_family;
        __u8            diag_state;
-       __u8            diag_mode;
+       union {
+               __u8    diag_mode;
+               __u8    diag_fallback; /* the old name of the field */
+       };
        __u8            diag_shutdown;
        struct inet_diag_sockid id;