[ovs-dev] [PATCH] dpctl: Fix broken flow deletion via ovs-dpctl due to missing ufid.

Eelco Chaudron echaudro at redhat.com
Mon Oct 5 12:04:09 UTC 2020



On 5 Oct 2020, at 12:09, Ilya Maximets wrote:

> Current code generates UFID for flows installed by ovs-dpctl.  This
> leads to inability to remove such flows by the same command.  Ex:
>
>   ovs-dpctl add-dp test
>   ovs-dpctl add-if test vport0
>   ovs-dpctl add-flow test 
> "in_port(0),eth(),eth_type(0x800),ipv4(src=100.1.0.1)" 0
>   ovs-dpctl del-flow test 
> "in_port(0),eth(),eth_type(0x800),ipv4(src=100.1.0.1)"
>
>   dpif|WARN|system at test: failed to flow_del (No such file or 
> directory)
>       ufid:e4457189-3990-4a01-bdcf-1e5f8b208711 in_port(0),
>       eth(src=00:00:00:00:00:00,dst=00:00:00:00:00:00),eth_type(0x0800),
>       ipv4(src=100.1.0.1,dst=0.0.0.0,proto=0,tos=0,ttl=0,frag=no)
>
>   ovs-dpctl: deleting flow (No such file or directory)
>   Perhaps you need to specify a UFID?
>
> During del-flow operation UFID is generated too, however resulted
> value is different from one generated during add-flow.  This happens
> because odp_flow_key_hash() function uses random base value for flow
> hashes which is different on every invocation.  That is not an issue
> while running 'ovs-appctl dpctl/{add,del}-flow' because execution
> of these requests happens in context of the OVS main process, i.e.
> there will be same random seed.
>
> Commit e61984e781e6 was intended to allow offloading for flows
> added by dpctl/add-flow unixctl command, so it's better to generate
> UFIDs conditionally inside dpctl command handler only for appctl
> invocations.  Offloading is not possible from ovs-dpctl utility 
> anyway.
>
> There are still couple of corner case:  It will not be possible to
> remove flow by 'ovs-appctl dpctl/del-flow' without specifying UFID if
> main OVS process was restarted since flow addition and it will not
> be possible to remove flow by ovs-dpctl without specifying UUID if
> it was added by 'ovs-appctl dpctl/add-flow'.  But these scenarios
> seems minor since these commands intended for testing only.
>
> Reported-by: Eelco Chaudron <echaudro at redhat.com>
> Reported-at: 
> https://mail.openvswitch.org/pipermail/ovs-dev/2020-September/374863.html
> Fixes: e61984e781e6 ("dpif-netlink: Generate ufids for installing TC 
> flowers")
> Signed-off-by: Ilya Maximets <i.maximets at ovn.org>
> ---

This change looks good to me, with one small comment below...
Also, verified this in my scenario, and all works as expected.

Acked-by: Eelco Chaudron <echaudro at redhat.com>
Tested-by: Eelco Chaudron <echaudro at redhat.com>

>
> Eelco, Tonghao, please test this with your scenarios.  I only tested
> with 'make check'.
>
>  lib/dpctl.c        | 21 ++++++++++++++++++++-
>  lib/dpif-netlink.c | 45 ---------------------------------------------
>  2 files changed, 20 insertions(+), 46 deletions(-)
>
> diff --git a/lib/dpctl.c b/lib/dpctl.c
> index 09ae97f25..2f859a753 100644
> --- a/lib/dpctl.c
> +++ b/lib/dpctl.c
> @@ -1157,6 +1157,16 @@ dpctl_put_flow(int argc, const char *argv[], 
> enum dpif_flow_put_flags flags,
>          goto out_freeactions;
>      }
>
> +    if (!ufid_present && dpctl_p->is_appctl) {
> +        /* Generating UFID for this flow so it could be offloaded to 
> HW.  We're
> +         * not doing that if invoked from ovs-dpctl utility because
> +         * odp_flow_key_hash() uses randomly generated base for flow 
> hashes
> +         * that will be different for each invocation.  And, anyway, 
> offloading
> +         * is only available via appctl. */
> +        odp_flow_key_hash(key.data, key.size, &ufid);
> +        ufid_present = true;
> +    }
> +
>      /* The flow will be added on all pmds currently in the datapath. 
> */
>      error = dpif_flow_put(dpif, flags,
>                            key.data, key.size,
> @@ -1268,6 +1278,7 @@ dpctl_del_flow(int argc, const char *argv[], 
> struct dpctl_params *dpctl_p)
>      struct ofpbuf mask; /* To be ignored. */
>      struct dpif *dpif;
>      ovs_u128 ufid;
> +    bool ufid_generated;
>      bool ufid_present;
>      struct simap port_names;
>      int n, error;
> @@ -1303,6 +1314,14 @@ dpctl_del_flow(int argc, const char *argv[], 
> struct dpctl_params *dpctl_p)
>          goto out;
>      }
>
> +    if (!ufid_present && dpctl_p->is_appctl) {
> +        /* While adding flow via appctl we're generating UFID to make 
> HW

Should be “While deleting…”

> +         * offloading possible.  Generating UFID here to be sure that 
> such
> +         * flows could be removed the same way they were added. */
> +        odp_flow_key_hash(key.data, key.size, &ufid);
> +        ufid_present = ufid_generated = true;
> +    }
> +
>      /* The flow will be deleted from all pmds currently in the 
> datapath. */
>      error = dpif_flow_del(dpif, key.data, key.size,
>                            ufid_present ? &ufid : NULL, PMD_ID_NULL,
> @@ -1310,7 +1329,7 @@ dpctl_del_flow(int argc, const char *argv[], 
> struct dpctl_params *dpctl_p)
>
>      if (error) {
>          dpctl_error(dpctl_p, error, "deleting flow");
> -        if (error == ENOENT && !ufid_present) {
> +        if (error == ENOENT && (!ufid_present || ufid_generated)) {
>              struct ds s;
>
>              ds_init(&s);
> diff --git a/lib/dpif-netlink.c b/lib/dpif-netlink.c
> index 7da4fb54d..2f881e4fa 100644
> --- a/lib/dpif-netlink.c
> +++ b/lib/dpif-netlink.c
> @@ -2237,55 +2237,12 @@ dpif_netlink_operate_chunks(struct 
> dpif_netlink *dpif, struct dpif_op **ops,
>      }
>  }
>
> -static void
> -dpif_netlink_try_update_ufid__(struct dpif_op *op, ovs_u128 *ufid)
> -{
> -    switch (op->type) {
> -    case DPIF_OP_FLOW_PUT:
> -        if (!op->flow_put.ufid) {
> -            odp_flow_key_hash(op->flow_put.key, op->flow_put.key_len,
> -                              ufid);
> -            op->flow_put.ufid = ufid;
> -        }
> -        break;
> -    case DPIF_OP_FLOW_DEL:
> -        if (!op->flow_del.ufid) {
> -            odp_flow_key_hash(op->flow_del.key, op->flow_del.key_len,
> -                              ufid);
> -            op->flow_del.ufid = ufid;
> -        }
> -        break;
> -    case DPIF_OP_FLOW_GET:
> -        if (!op->flow_get.ufid) {
> -            odp_flow_key_hash(op->flow_get.key, op->flow_get.key_len,
> -                              ufid);
> -            op->flow_get.ufid = ufid;
> -        }
> -        break;
> -    case DPIF_OP_EXECUTE:
> -    default:
> -        break;
> -    }
> -}
> -
> -static void
> -dpif_netlink_try_update_ufid(struct dpif_op **ops, ovs_u128 *ufid,
> -                             size_t n_ops)
> -{
> -    int i;
> -
> -    for (i = 0; i < n_ops; i++) {
> -        dpif_netlink_try_update_ufid__(ops[i], &ufid[i]);
> -    }
> -}
> -
>  static void
>  dpif_netlink_operate(struct dpif *dpif_, struct dpif_op **ops, size_t 
> n_ops,
>                       enum dpif_offload_type offload_type)
>  {
>      struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
>      struct dpif_op *new_ops[OPERATE_MAX_OPS];
> -    ovs_u128 ufids[OPERATE_MAX_OPS];
>      int count = 0;
>      int i = 0;
>      int err = 0;
> @@ -2295,8 +2252,6 @@ dpif_netlink_operate(struct dpif *dpif_, struct 
> dpif_op **ops, size_t n_ops,
>          return;
>      }
>
> -    dpif_netlink_try_update_ufid(ops, ufids, n_ops);
> -
>      if (offload_type != DPIF_OFFLOAD_NEVER && 
> netdev_is_flow_api_enabled()) {
>          while (n_ops > 0) {
>              count = 0;
> -- 
> 2.25.4



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