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via-rhine: close SMP transmit races.

Browse source 
7ab87ff4c7 ("via-rhine: move work from
irq handler to softirq and beyond") forgot to explicitely control the
lifespan of the tx_dirty and tx_cur pointers.

Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
françois romieu 2015-05-01 22:14:45 +02:00 committed by David S. Miller
parent e1efa87241
commit 3a5a883a8a
1 changed files with 45 additions and 6 deletions
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51
drivers/net/ethernet/via/via-rhine.c
View file

@ -1779,6 +1779,11 @@ static void rhine_tx_timeout(struct net_device *dev)
schedule_work(&rp->reset_task);
}
static inline bool rhine_tx_queue_full(struct rhine_private *rp)
{
return (rp->cur_tx - rp->dirty_tx) >= TX_QUEUE_LEN;
}
static netdev_tx_t rhine_start_tx(struct sk_buff *skb,
struct net_device *dev)
{
@ -1854,6 +1859,12 @@ static netdev_tx_t rhine_start_tx(struct sk_buff *skb,
wmb();
rp->cur_tx++;
/*
* Nobody wants cur_tx write to rot for ages after the NIC will have
* seen the transmit request, especially as the transmit completion
* handler could miss it.
*/
smp_wmb();
/* Non-x86 Todo: explicitly flush cache lines here. */
@ -1866,8 +1877,14 @@ static netdev_tx_t rhine_start_tx(struct sk_buff *skb,
ioaddr + ChipCmd1);
IOSYNC;
if (rp->cur_tx == rp->dirty_tx + TX_QUEUE_LEN)
/* dirty_tx may be pessimistically out-of-sync. See rhine_tx. */
if (rhine_tx_queue_full(rp)) {
netif_stop_queue(dev);
smp_rmb();
/* Rejuvenate. */
if (!rhine_tx_queue_full(rp))
netif_wake_queue(dev);
}
netif_dbg(rp, tx_queued, dev, "Transmit frame #%d queued in slot %d\n",
rp->cur_tx - 1, entry);
@ -1915,13 +1932,24 @@ static void rhine_tx(struct net_device *dev)
{
struct rhine_private *rp = netdev_priv(dev);
struct device *hwdev = dev->dev.parent;
int txstatus = 0, entry = rp->dirty_tx % TX_RING_SIZE;
unsigned int pkts_compl = 0, bytes_compl = 0;
unsigned int dirty_tx = rp->dirty_tx;
unsigned int cur_tx;
struct sk_buff *skb;
/*
* The race with rhine_start_tx does not matter here as long as the
* driver enforces a value of cur_tx that was relevant when the
* packet was scheduled to the network chipset.
* Executive summary: smp_rmb() balances smp_wmb() in rhine_start_tx.
*/
smp_rmb();
cur_tx = rp->cur_tx;
/* find and cleanup dirty tx descriptors */
while (rp->dirty_tx != rp->cur_tx) {
txstatus = le32_to_cpu(rp->tx_ring[entry].tx_status);
while (dirty_tx != cur_tx) {
unsigned int entry = dirty_tx % TX_RING_SIZE;
u32 txstatus = le32_to_cpu(rp->tx_ring[entry].tx_status);
netif_dbg(rp, tx_done, dev, "Tx scavenge %d status %08x\n",
entry, txstatus);
if (txstatus & DescOwn)
@ -1970,12 +1998,23 @@ static void rhine_tx(struct net_device *dev)
pkts_compl++;
dev_consume_skb_any(skb);
rp->tx_skbuff[entry] = NULL;
entry = (++rp->dirty_tx) % TX_RING_SIZE;
dirty_tx++;
}
rp->dirty_tx = dirty_tx;
/* Pity we can't rely on the nearby BQL completion implicit barrier. */
smp_wmb();
netdev_completed_queue(dev, pkts_compl, bytes_compl);
if ((rp->cur_tx - rp->dirty_tx) < TX_QUEUE_LEN - 4)
/* cur_tx may be optimistically out-of-sync. See rhine_start_tx. */
if (!rhine_tx_queue_full(rp) && netif_queue_stopped(dev)) {
netif_wake_queue(dev);
smp_rmb();
/* Rejuvenate. */
if (rhine_tx_queue_full(rp))
netif_stop_queue(dev);
}
}
/**