Messages in this thread Patch in this message |  | | From | Vladimir Oltean <> | Subject | [PATCH net-next 1/2] net: dsa: Remove deferred_xmit from dsa_skb_cb | Date | Fri, 27 Dec 2019 03:42:07 +0200 |
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The introduction of the deferred xmit mechanism in DSA has made the hotpath slightly more inefficient for everybody, since DSA_SKB_CB(skb)->deferred_xmit needed to be initialized to false for every transmitted frame, in order to figure out whether the driver requested deferral or not. That was necessary to avoid kfree_skb from freeing the skb.
But actually we can just remove that variable in the skb->cb and counteract the effect of kfree_skb with skb_get, much to the same effect. The advantage, of course, being that anybody who doesn't use deferred xmit doesn't need to do any extra operation in the hotpath.
Signed-off-by: Vladimir Oltean <olteanv@gmail.com> --- include/net/dsa.h | 1 - net/dsa/slave.c | 12 ++++++------ 2 files changed, 6 insertions(+), 7 deletions(-)
diff --git a/include/net/dsa.h b/include/net/dsa.h index 6767dc3f66c0..5d510a4da5d0 100644 --- a/include/net/dsa.h +++ b/include/net/dsa.h @@ -88,7 +88,6 @@ struct dsa_device_ops { struct dsa_skb_cb { struct sk_buff *clone; - bool deferred_xmit; }; struct __dsa_skb_cb { diff --git a/net/dsa/slave.c b/net/dsa/slave.c index 78ffc87dc25e..9f7e47dcdc20 100644 --- a/net/dsa/slave.c +++ b/net/dsa/slave.c @@ -518,7 +518,6 @@ static netdev_tx_t dsa_slave_xmit(struct sk_buff *skb, struct net_device *dev) s->tx_bytes += skb->len; u64_stats_update_end(&s->syncp); - DSA_SKB_CB(skb)->deferred_xmit = false; DSA_SKB_CB(skb)->clone = NULL; /* Identify PTP protocol packets, clone them, and pass them to the @@ -531,8 +530,7 @@ static netdev_tx_t dsa_slave_xmit(struct sk_buff *skb, struct net_device *dev) */ nskb = p->xmit(skb, dev); if (!nskb) { - if (!DSA_SKB_CB(skb)->deferred_xmit) - kfree_skb(skb); + kfree_skb(skb); return NETDEV_TX_OK; } @@ -543,10 +541,12 @@ void *dsa_defer_xmit(struct sk_buff *skb, struct net_device *dev) { struct dsa_port *dp = dsa_slave_to_port(dev); - DSA_SKB_CB(skb)->deferred_xmit = true; - - skb_queue_tail(&dp->xmit_queue, skb); + /* Increase refcount so the kfree_skb in dsa_slave_xmit + * won't really free the packet. + */ + skb_queue_tail(&dp->xmit_queue, skb_get(skb)); schedule_work(&dp->xmit_work); + return NULL; } EXPORT_SYMBOL_GPL(dsa_defer_xmit); -- 2.17.1
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