net/tap: fix isolation mode toggling

Running testpmd command "flow isolae <port> 0" (i.e. disabling flow
isolation) followed by command "flow isolate <port> 1" (i.e. enabling
flow isolation) may result in a TAP error:
PMD: Kernel refused TC filter rule creation (17): File exists

Root cause analysis: when disabling flow isolation we keep the local
rule to redirect packets on TX (TAP_REMOTE_TX index) while we add it
again when enabling flow isolation. As a result this rule is added
two times in a row which results in "File exists" error.
The fix is to identify the "File exists" error and silently ignore it.

Another issue occurs when enabling isolation mode several times in a
row in which case the same tc rules are added consecutively and
rte_flow structs are added to a linked list before removing the
previous rte_flow structs.
The fix is to act upon isolation mode command only when there is a
change from "0" to "1" (or vice versa).

Fixes: f503d2694825 ("net/tap: support flow API isolated mode")
Cc: stable@dpdk.org
Reviewed-by: Raslan Darawsheh <rasland@mellanox.com>
Signed-off-by: Ophir Munk <ophirmu@mellanox.com>
Acked-by: Keith Wiles <keith.wiles@intel.com>

diff --git a/drivers/net/tap/tap_flow.c b/drivers/net/tap/tap_flow.c
index aab9eef..6b60e6d 100644 (file)
--- a/drivers/net/tap/tap_flow.c
+++ b/drivers/net/tap/tap_flow.c
@@ -1568,10 +1568,14 @@ tap_flow_isolate(struct rte_eth_dev *dev,
 {
        struct pmd_internals *pmd = dev->data->dev_private;
 
+       /* normalize 'set' variable to contain 0 or 1 values */
        if (set)
-               pmd->flow_isolate = 1;
-       else
-               pmd->flow_isolate = 0;
+               set = 1;
+       /* if already in the right isolation mode - nothing to do */
+       if ((set ^ pmd->flow_isolate) == 0)
+               return 0;
+       /* mark the isolation mode for tap_flow_implicit_create() */
+       pmd->flow_isolate = set;
        /*
         * If netdevice is there, setup appropriate flow rules immediately.
         * Otherwise it will be set when bringing up the netdevice (tun_alloc).
@@ -1579,20 +1583,20 @@ tap_flow_isolate(struct rte_eth_dev *dev,
        if (!pmd->rxq[0].fd)
                return 0;
        if (set) {
-               struct rte_flow *flow;
+               struct rte_flow *remote_flow;
 
                while (1) {
-                       flow = LIST_FIRST(&pmd->implicit_flows);
-                       if (!flow)
+                       remote_flow = LIST_FIRST(&pmd->implicit_flows);
+                       if (!remote_flow)
                                break;
                        /*
                         * Remove all implicit rules on the remote.
                         * Keep the local rule to redirect packets on TX.
                         * Keep also the last implicit local rule: ISOLATE.
                         */
-                       if (flow->msg.t.tcm_ifindex == pmd->if_index)
+                       if (remote_flow->msg.t.tcm_ifindex == pmd->if_index)
                                break;
-                       if (tap_flow_destroy_pmd(pmd, flow, NULL) < 0)
+                       if (tap_flow_destroy_pmd(pmd, remote_flow, NULL) < 0)
                                goto error;
                }
                /* Switch the TC rule according to pmd->flow_isolate */
@@ -1739,8 +1743,8 @@ int tap_flow_implicit_create(struct pmd_internals *pmd,
        }
        err = tap_nl_recv_ack(pmd->nlsk_fd);
        if (err < 0) {
-               /* Silently ignore re-entering remote promiscuous rule */
-               if (errno == EEXIST && idx == TAP_REMOTE_PROMISC)
+               /* Silently ignore re-entering existing rule */
+               if (errno == EEXIST)
                        goto success;
                TAP_LOG(ERR,
                        "Kernel refused TC filter rule creation (%d): %s",