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gianfar: Revive SKB recycling
Before calling gfar_clean_tx_ring() the driver grabs an irqsave spinlock, and then tries to recycle skbs. But since skb_recycle_check() returns 0 with IRQs disabled, we'll never recycle any skbs. It appears that gfar_clean_tx_ring() and gfar_start_xmit() are mostly idependent and can work in parallel, except when they modify num_txbdfree. So we can drop the lock from most sections and thus fix the skb recycling. Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com> Acked-by: Kumar Gala <galak@kernel.crashing.org> Signed-off-by: David S. Miller <davem@davemloft.net>
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1 changed files with 19 additions and 12 deletions
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@ -1928,14 +1928,11 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
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/* total number of fragments in the SKB */
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nr_frags = skb_shinfo(skb)->nr_frags;
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spin_lock_irqsave(&tx_queue->txlock, flags);
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/* check if there is space to queue this packet */
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if ((nr_frags+1) > tx_queue->num_txbdfree) {
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/* no space, stop the queue */
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netif_tx_stop_queue(txq);
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dev->stats.tx_fifo_errors++;
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spin_unlock_irqrestore(&tx_queue->txlock, flags);
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return NETDEV_TX_BUSY;
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}
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@ -1998,6 +1995,20 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
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lstatus |= BD_LFLAG(TXBD_CRC | TXBD_READY) | skb_headlen(skb);
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/*
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* We can work in parallel with gfar_clean_tx_ring(), except
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* when modifying num_txbdfree. Note that we didn't grab the lock
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* when we were reading the num_txbdfree and checking for available
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* space, that's because outside of this function it can only grow,
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* and once we've got needed space, it cannot suddenly disappear.
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*
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* The lock also protects us from gfar_error(), which can modify
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* regs->tstat and thus retrigger the transfers, which is why we
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* also must grab the lock before setting ready bit for the first
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* to be transmitted BD.
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*/
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spin_lock_irqsave(&tx_queue->txlock, flags);
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/*
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* The powerpc-specific eieio() is used, as wmb() has too strong
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* semantics (it requires synchronization between cacheable and
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@ -2225,6 +2236,8 @@ static int gfar_clean_tx_ring(struct gfar_priv_tx_q *tx_queue)
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skb_dirtytx = tx_queue->skb_dirtytx;
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while ((skb = tx_queue->tx_skbuff[skb_dirtytx])) {
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unsigned long flags;
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frags = skb_shinfo(skb)->nr_frags;
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lbdp = skip_txbd(bdp, frags, base, tx_ring_size);
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@ -2269,7 +2282,9 @@ static int gfar_clean_tx_ring(struct gfar_priv_tx_q *tx_queue)
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TX_RING_MOD_MASK(tx_ring_size);
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howmany++;
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spin_lock_irqsave(&tx_queue->txlock, flags);
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tx_queue->num_txbdfree += frags + 1;
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spin_unlock_irqrestore(&tx_queue->txlock, flags);
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}
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/* If we freed a buffer, we can restart transmission, if necessary */
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@ -2548,7 +2563,6 @@ static int gfar_poll(struct napi_struct *napi, int budget)
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int tx_cleaned = 0, i, left_over_budget = budget;
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unsigned long serviced_queues = 0;
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int num_queues = 0;
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unsigned long flags;
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num_queues = gfargrp->num_rx_queues;
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budget_per_queue = budget/num_queues;
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@ -2568,14 +2582,7 @@ static int gfar_poll(struct napi_struct *napi, int budget)
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rx_queue = priv->rx_queue[i];
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tx_queue = priv->tx_queue[rx_queue->qindex];
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/* If we fail to get the lock,
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* don't bother with the TX BDs */
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if (spin_trylock_irqsave(&tx_queue->txlock, flags)) {
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tx_cleaned += gfar_clean_tx_ring(tx_queue);
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spin_unlock_irqrestore(&tx_queue->txlock,
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flags);
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}
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tx_cleaned += gfar_clean_tx_ring(tx_queue);
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rx_cleaned_per_queue = gfar_clean_rx_ring(rx_queue,
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budget_per_queue);
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rx_cleaned += rx_cleaned_per_queue;
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