net/smc: fix toleration of fake add_link messages

Older SMCR implementations had no link failover support and used one
link only. Because the handshake protocol requires to try the
establishment of a second link the old code sent a fake add_link message
and declined any server response afterwards.
The current code supports multiple links and inspects the received fake
add_link message more closely. To tolerate the fake add_link messages
smc_llc_is_local_add_link() needs an improved check of the message to
be able to separate between locally enqueued and fake add_link messages.
And smc_llc_cli_add_link() needs to check if the provided qp_mtu size is
invalid and reject the add_link request in that case.

Fixes: c48254fa48e5 ("net/smc: move add link processing for new device into llc layer")
Reviewed-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/smc/smc_llc.c b/net/smc/smc_llc.c
index df5b0a6ea8488ffb53fb5a4aa5b564d557ee4400..3ea33466ebe98c7d39afd442ed37bcaa0fab5b8a 100644 (file)
--- a/net/smc/smc_llc.c
+++ b/net/smc/smc_llc.c
@@ -841,6 +841,9 @@ int smc_llc_cli_add_link(struct smc_link *link, struct smc_llc_qentry *qentry)
        struct smc_init_info ini;
        int lnk_idx, rc = 0;
 
+       if (!llc->qp_mtu)
+               goto out_reject;
+
        ini.vlan_id = lgr->vlan_id;
        smc_pnet_find_alt_roce(lgr, &ini, link->smcibdev);
        if (!memcmp(llc->sender_gid, link->peer_gid, SMC_GID_SIZE) &&
@@ -917,10 +920,20 @@ out:
        kfree(qentry);
 }
 
+static bool smc_llc_is_empty_llc_message(union smc_llc_msg *llc)
+{
+       int i;
+
+       for (i = 0; i < ARRAY_SIZE(llc->raw.data); i++)
+               if (llc->raw.data[i])
+                       return false;
+       return true;
+}
+
 static bool smc_llc_is_local_add_link(union smc_llc_msg *llc)
 {
        if (llc->raw.hdr.common.type == SMC_LLC_ADD_LINK &&
-           !llc->add_link.qp_mtu && !llc->add_link.link_num)
+           smc_llc_is_empty_llc_message(llc))
                return true;
        return false;
 }