diff options
author | Anton Vorontsov <avorontsov@ru.mvista.com> | 2009-11-10 14:11:10 +0000 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2009-11-11 19:03:36 -0800 |
commit | a3bc1f11e9b867a4f49505ecac486a33af248b2e (patch) | |
tree | 026512ce0362e0f13f0c35d2fc6bc01d2498a2ed /drivers | |
parent | 836cf7faf8c75743477ed6ed341cce491f3183fb (diff) |
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>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/net/gianfar.c | 31 |
1 files changed, 19 insertions, 12 deletions
diff --git a/drivers/net/gianfar.c b/drivers/net/gianfar.c index fde430a0b84b..16def131c390 100644 --- a/drivers/net/gianfar.c +++ b/drivers/net/gianfar.c @@ -1928,14 +1928,11 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev) /* total number of fragments in the SKB */ nr_frags = skb_shinfo(skb)->nr_frags; - spin_lock_irqsave(&tx_queue->txlock, flags); - /* check if there is space to queue this packet */ if ((nr_frags+1) > tx_queue->num_txbdfree) { /* no space, stop the queue */ netif_tx_stop_queue(txq); dev->stats.tx_fifo_errors++; - spin_unlock_irqrestore(&tx_queue->txlock, flags); return NETDEV_TX_BUSY; } @@ -1999,6 +1996,20 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev) lstatus |= BD_LFLAG(TXBD_CRC | TXBD_READY) | skb_headlen(skb); /* + * We can work in parallel with gfar_clean_tx_ring(), except + * when modifying num_txbdfree. Note that we didn't grab the lock + * when we were reading the num_txbdfree and checking for available + * space, that's because outside of this function it can only grow, + * and once we've got needed space, it cannot suddenly disappear. + * + * The lock also protects us from gfar_error(), which can modify + * regs->tstat and thus retrigger the transfers, which is why we + * also must grab the lock before setting ready bit for the first + * to be transmitted BD. + */ + spin_lock_irqsave(&tx_queue->txlock, flags); + + /* * The powerpc-specific eieio() is used, as wmb() has too strong * semantics (it requires synchronization between cacheable and * uncacheable mappings, which eieio doesn't provide and which we @@ -2225,6 +2236,8 @@ static int gfar_clean_tx_ring(struct gfar_priv_tx_q *tx_queue) skb_dirtytx = tx_queue->skb_dirtytx; while ((skb = tx_queue->tx_skbuff[skb_dirtytx])) { + unsigned long flags; + frags = skb_shinfo(skb)->nr_frags; lbdp = skip_txbd(bdp, frags, base, tx_ring_size); @@ -2269,7 +2282,9 @@ static int gfar_clean_tx_ring(struct gfar_priv_tx_q *tx_queue) TX_RING_MOD_MASK(tx_ring_size); howmany++; + spin_lock_irqsave(&tx_queue->txlock, flags); tx_queue->num_txbdfree += frags + 1; + spin_unlock_irqrestore(&tx_queue->txlock, flags); } /* If we freed a buffer, we can restart transmission, if necessary */ @@ -2548,7 +2563,6 @@ static int gfar_poll(struct napi_struct *napi, int budget) int tx_cleaned = 0, i, left_over_budget = budget; unsigned long serviced_queues = 0; int num_queues = 0; - unsigned long flags; num_queues = gfargrp->num_rx_queues; budget_per_queue = budget/num_queues; @@ -2568,14 +2582,7 @@ static int gfar_poll(struct napi_struct *napi, int budget) rx_queue = priv->rx_queue[i]; tx_queue = priv->tx_queue[rx_queue->qindex]; - /* If we fail to get the lock, - * don't bother with the TX BDs */ - if (spin_trylock_irqsave(&tx_queue->txlock, flags)) { - tx_cleaned += gfar_clean_tx_ring(tx_queue); - spin_unlock_irqrestore(&tx_queue->txlock, - flags); - } - + tx_cleaned += gfar_clean_tx_ring(tx_queue); rx_cleaned_per_queue = gfar_clean_rx_ring(rx_queue, budget_per_queue); rx_cleaned += rx_cleaned_per_queue; |