Partially revert "net/smc: Add netlink net namespace support"

The change of sizeof(struct smc_diag_linkinfo) by commit 79d39fc503b4
("net/smc: Add netlink net namespace support") introduced an ABI
regression: since struct smc_diag_lgrinfo contains an object of
type "struct smc_diag_linkinfo", offset of all subsequent members
of struct smc_diag_lgrinfo was changed by that change.

As result, applications compiled with the old version
of struct smc_diag_linkinfo will receive garbage in
struct smc_diag_lgrinfo.role if the kernel implements
this new version of struct smc_diag_linkinfo.

Fix this regression by reverting the part of commit 79d39fc503b4 that
changes struct smc_diag_linkinfo.  After all, there is SMC_GEN_NETLINK
interface which is good enough, so there is probably no need to touch
the smc_diag ABI in the first place.

Fixes: 79d39fc503b4 ("net/smc: Add netlink net namespace support")
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Reviewed-by: Karsten Graul <kgraul@linux.ibm.com>
Link: https://lore.kernel.org/r/20220202030904.GA9742@altlinux.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/uapi/linux/smc_diag.h b/include/uapi/linux/smc_diag.h
index c7008d8..8cb3a6f 100644 (file)
--- a/include/uapi/linux/smc_diag.h
+++ b/include/uapi/linux/smc_diag.h
@@ -84,12 +84,11 @@ struct smc_diag_conninfo {
 /* SMC_DIAG_LINKINFO */
 
 struct smc_diag_linkinfo {
-       __u8            link_id;                    /* link identifier */
-       __u8            ibname[IB_DEVICE_NAME_MAX]; /* name of the RDMA device */
-       __u8            ibport;                     /* RDMA device port number */
-       __u8            gid[40];                    /* local GID */
-       __u8            peer_gid[40];               /* peer GID */
-       __aligned_u64   net_cookie;                 /* RDMA device net namespace */
+       __u8 link_id;                   /* link identifier */
+       __u8 ibname[IB_DEVICE_NAME_MAX]; /* name of the RDMA device */
+       __u8 ibport;                    /* RDMA device port number */
+       __u8 gid[40];                   /* local GID */
+       __u8 peer_gid[40];              /* peer GID */
 };
 
 struct smc_diag_lgrinfo {

diff --git a/net/smc/smc_diag.c b/net/smc/smc_diag.c
index b8898c7..1fca2f9 100644 (file)
--- a/net/smc/smc_diag.c
+++ b/net/smc/smc_diag.c
@@ -146,13 +146,11 @@ static int __smc_diag_dump(struct sock *sk, struct sk_buff *skb,
            (req->diag_ext & (1 << (SMC_DIAG_LGRINFO - 1))) &&
            !list_empty(&smc->conn.lgr->list)) {
                struct smc_link *link = smc->conn.lnk;
-               struct net *net = read_pnet(&link->smcibdev->ibdev->coredev.rdma_net);
 
                struct smc_diag_lgrinfo linfo = {
                        .role = smc->conn.lgr->role,
                        .lnk[0].ibport = link->ibport,
                        .lnk[0].link_id = link->link_id,
-                       .lnk[0].net_cookie = net->net_cookie,
                };
 
                memcpy(linfo.lnk[0].ibname,