Re: [dpdk-dev] [PATCH v1] net/tap: fix isolation mode toggling

[Ophir Munk <ophirmu@mellanox.com>]

Hi Keith,

> -----Original Message-----
> From: Wiles, Keith [mailto:keith.wiles@intel.com]
> Sent: Monday, May 14, 2018 3:33 PM
> To: Ophir Munk <ophirmu@mellanox.com>
> Cc: dev@dpdk.org; Pascal Mazon <pascal.mazon@6wind.com>; Thomas
> Monjalon <thomas@monjalon.net>; Olga Shern <olgas@mellanox.com>;
> stable@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v1] net/tap: fix isolation mode toggling
> 
> 
> 
> > On May 7, 2018, at 3:36 AM, Ophir Munk <ophirmu@mellanox.com>
> wrote:
> >
> > 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 raw which results in "File exists" error.
> 
> /raw/row

Fixed in v3

> > The fix is to identify the "File exists" error and silently ignore it.
> >
> > Another issue occurs when enabling isolation mode several times in a
> > raw in which case the same tc rules are added consecutively and
> 
> /raw/row

Fixed in v3

> > 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
> >
> > Signed-off-by: Ophir Munk <ophirmu@mellanox.com>
> > ---
> > drivers/net/tap/tap_flow.c | 37 +++++++++++++++++++++++--------------
> > 1 file changed, 23 insertions(+), 14 deletions(-)
> >
> > diff --git a/drivers/net/tap/tap_flow.c b/drivers/net/tap/tap_flow.c
> > index aab9eef..91f15f6 100644
> > --- a/drivers/net/tap/tap_flow.c
> > +++ b/drivers/net/tap/tap_flow.c
> > @@ -1568,10 +1568,10 @@ tap_flow_isolate(struct rte_eth_dev *dev, {
> > 	struct pmd_internals *pmd = dev->data->dev_private;
> >
> > -	if (set)
> > -		pmd->flow_isolate = 1;
> > -	else
> > -		pmd->flow_isolate = 0;
> > +	/* if already in the right isolation mode - nothing to do */
> > +	if ((!!set ^ pmd->flow_isolate) == 0)
> > +		return 0;
> > +	pmd->flow_isolate = !!set;
> 
> Using double negation is not very readable IMO, I would prefer this
> converted to a true boolean type if required.
> 

Double negation usage was eliminated. 

> variable ‘set' here should a 0 or 1 already, please expand this code to not use
> !!, using this in modern compilers should not be required. I understand this
> maybe shorted to write, but not very readable IMO and we need to make
> DPDK readable.
> 
> > 	/*
> > 	 * If netdevice is there, setup appropriate flow rules immediately.
> > 	 * Otherwise it will be set when bringing up the netdevice (tun_alloc).
> > @@ -1579,21 +1579,30 @@ 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)
> > +		while (!LIST_EMPTY(&pmd->implicit_flows)) {
> > +			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)
> > -				break;
> > -			if (tap_flow_destroy_pmd(pmd, flow, NULL) < 0)
> > -				goto error;
> > +			if (remote_flow->msg.t.tcm_ifindex != pmd-
> >if_index) {
> > +				/*
> > +				 * remove TC from kernel and
> > +				 * remote_flow from list
> > +				 */
> > +				if (tap_flow_destroy_pmd(pmd,
> remote_flow,
> > +						NULL) < 0)
> > +					goto error;
> > +			} else {
> > +				/* remove remote_flow from list */
> > +				LIST_REMOVE(remote_flow, next);
> > +				rte_free(remote_flow);
> > +			}
> > 		}
> > 		/* Switch the TC rule according to pmd->flow_isolate */
> > 		if (tap_flow_implicit_create(pmd, TAP_ISOLATE) == -1) @@ -
> 1739,8
> > +1748,8 @@ 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",
> > --
> > 2.7.4
> >
> 
> Regards,
> Keith