netdev - [PATCH net 2/2] nfp: flower: prevent offload if rhashtable insert fails

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Message-Id: <20181127220412.31178-2-jakub.kicinski@netronome.com>
Date:   Tue, 27 Nov 2018 14:04:12 -0800
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     davem@...emloft.net
Cc:     oss-drivers@...ronome.com, netdev@...r.kernel.org,
        John Hurley <john.hurley@...ronome.com>,
        Stephen Rothwell <sfr@...b.auug.org.au>
Subject: [PATCH net 2/2] nfp: flower: prevent offload if rhashtable insert fails

From: John Hurley <john.hurley@...ronome.com>

For flow offload adds, if the rhash insert code fails, the flow will still
have been offloaded but the reference to it in the driver freed.

Re-order the offload setup calls to ensure that a flow will only be written
to FW if a kernel reference is held and stored in the rhashtable. Remove
this hashtable entry if the offload fails.

Fixes: c01d0efa5136 ("nfp: flower: use rhashtable for flow caching")
Signed-off-by: John Hurley <john.hurley@...ronome.com>
Reviewed-by: Pieter Jansen van Vuuren <pieter.jansenvanvuuren@...ronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
---
Merge note: there will be a slight merge conflict with net-next
here:
 - the first argument of nfp_flower_xmit_flow() changed from 'netdev'
   to 'app';
 - we only bump the port offload cnt if (port).

FWIW the net-next version of the patch can be found at:

     git://git.kernel.org/pub/scm/linux/kernel/git/kuba/linux.git

     17ed95873d51 nfp: flower: prevent offload if rhashtable insert fails
     d857fc8f472b nfp: flower: release metadata on offload failure

CC: Stephen Rothwell <sfr@...b.auug.org.au> # for linux-next
---
 .../net/ethernet/netronome/nfp/flower/offload.c    | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/netronome/nfp/flower/offload.c b/drivers/net/ethernet/netronome/nfp/flower/offload.c
index c3ad8d737cf0..2f49eb75f3cc 100644
--- a/drivers/net/ethernet/netronome/nfp/flower/offload.c
+++ b/drivers/net/ethernet/netronome/nfp/flower/offload.c
@@ -476,17 +476,17 @@ nfp_flower_add_offload(struct nfp_app *app, struct net_device *netdev,
 	if (err)
 		goto err_destroy_flow;
 
-	err = nfp_flower_xmit_flow(netdev, flow_pay,
-				   NFP_FLOWER_CMSG_TYPE_FLOW_ADD);
-	if (err)
-		goto err_release_metadata;
-
 	flow_pay->tc_flower_cookie = flow->cookie;
 	err = rhashtable_insert_fast(&priv->flow_table, &flow_pay->fl_node,
 				     nfp_flower_table_params);
 	if (err)
 		goto err_release_metadata;
 
+	err = nfp_flower_xmit_flow(netdev, flow_pay,
+				   NFP_FLOWER_CMSG_TYPE_FLOW_ADD);
+	if (err)
+		goto err_remove_rhash;
+
 	port->tc_offload_cnt++;
 
 	/* Deallocate flow payload when flower rule has been destroyed. */
@@ -494,6 +494,10 @@ nfp_flower_add_offload(struct nfp_app *app, struct net_device *netdev,
 
 	return 0;
 
+err_remove_rhash:
+	WARN_ON_ONCE(rhashtable_remove_fast(&priv->flow_table,
+					    &flow_pay->fl_node,
+					    nfp_flower_table_params));
 err_release_metadata:
 	nfp_modify_flow_metadata(app, flow_pay);
 err_destroy_flow:
-- 
2.17.1