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net/sonic: Add mutual exclusion for accessing shared state

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[ Upstream commit 865ad2f2201dc18685ba2686f13217f8b3a9c52c ]

The netif_stop_queue() call in sonic_send_packet() races with the
netif_wake_queue() call in sonic_interrupt(). This causes issues
like "NETDEV WATCHDOG: eth0 (macsonic): transmit queue 0 timed out".
Fix this by disabling interrupts when accessing tx_skb[] and next_tx.
Update a comment to clarify the synchronization properties.

Fixes: efcce83936 ("[PATCH] macsonic/jazzsonic network drivers update")
Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Finn Thain 2020-01-23 09:07:26 +11:00 committed by Greg Kroah-Hartman
parent 5d47f5ed5a
commit 3c8a4483d8
2 changed files with 36 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

49
drivers/net/ethernet/natsemi/sonic.c
View File

@ -50,6 +50,8 @@ static int sonic_open(struct net_device *dev)
if (sonic_debug > 2)
printk("sonic_open: initializing sonic driver.\n");
spin_lock_init(&lp->lock);
for (i = 0; i < SONIC_NUM_RRS; i++) {
struct sk_buff *skb = netdev_alloc_skb(dev, SONIC_RBSIZE + 2);
if (skb == NULL) {
@ -194,8 +196,6 @@ static void sonic_tx_timeout(struct net_device *dev)
* wake the tx queue
* Concurrently with all of this, the SONIC is potentially writing to
* the status flags of the TDs.
* Until some mutual exclusion is added, this code will not work with SMP. However,
* MIPS Jazz machines and m68k Macs were all uni-processor machines.
*/
static int sonic_send_packet(struct sk_buff *skb, struct net_device *dev)
@ -203,7 +203,8 @@ static int sonic_send_packet(struct sk_buff *skb, struct net_device *dev)
struct sonic_local *lp = netdev_priv(dev);
dma_addr_t laddr;
int length;
int entry = lp->next_tx;
int entry;
unsigned long flags;
if (sonic_debug > 2)
printk("sonic_send_packet: skb=%p, dev=%p\n", skb, dev);
@ -226,6 +227,10 @@ static int sonic_send_packet(struct sk_buff *skb, struct net_device *dev)
return NETDEV_TX_OK;
}
spin_lock_irqsave(&lp->lock, flags);
entry = lp->next_tx;
sonic_tda_put(dev, entry, SONIC_TD_STATUS, 0); /* clear status */
sonic_tda_put(dev, entry, SONIC_TD_FRAG_COUNT, 1); /* single fragment */
sonic_tda_put(dev, entry, SONIC_TD_PKTSIZE, length); /* length of packet */
@ -235,10 +240,6 @@ static int sonic_send_packet(struct sk_buff *skb, struct net_device *dev)
sonic_tda_put(dev, entry, SONIC_TD_LINK,
sonic_tda_get(dev, entry, SONIC_TD_LINK) | SONIC_EOL);
/*
* Must set tx_skb[entry] only after clearing status, and
* before clearing EOL and before stopping queue
*/
wmb();
lp->tx_len[entry] = length;
lp->tx_laddr[entry] = laddr;
@ -263,6 +264,8 @@ static int sonic_send_packet(struct sk_buff *skb, struct net_device *dev)
SONIC_WRITE(SONIC_CMD, SONIC_CR_TXP);
spin_unlock_irqrestore(&lp->lock, flags);
return NETDEV_TX_OK;
}
@ -275,9 +278,21 @@ static irqreturn_t sonic_interrupt(int irq, void *dev_id)
struct net_device *dev = dev_id;
struct sonic_local *lp = netdev_priv(dev);
int status;
unsigned long flags;
/* The lock has two purposes. Firstly, it synchronizes sonic_interrupt()
* with sonic_send_packet() so that the two functions can share state.
* Secondly, it makes sonic_interrupt() re-entrant, as that is required
* by macsonic which must use two IRQs with different priority levels.
*/
spin_lock_irqsave(&lp->lock, flags);
status = SONIC_READ(SONIC_ISR) & SONIC_IMR_DEFAULT;
if (!status) {
spin_unlock_irqrestore(&lp->lock, flags);
if (!(status = SONIC_READ(SONIC_ISR) & SONIC_IMR_DEFAULT))
return IRQ_NONE;
}
do {
if (status & SONIC_INT_PKTRX) {
@ -292,11 +307,12 @@ static irqreturn_t sonic_interrupt(int irq, void *dev_id)
int td_status;
int freed_some = 0;
/* At this point, cur_tx is the index of a TD that is one of:
* unallocated/freed (status set & tx_skb[entry] clear)
* allocated and sent (status set & tx_skb[entry] set )
* allocated and not yet sent (status clear & tx_skb[entry] set )
* still being allocated by sonic_send_packet (status clear & tx_skb[entry] clear)
/* The state of a Transmit Descriptor may be inferred
* from { tx_skb[entry], td_status } as follows.
* { clear, clear } => the TD has never been used
* { set, clear } => the TD was handed to SONIC
* { set, set } => the TD was handed back
* { clear, set } => the TD is available for re-use
*/
if (sonic_debug > 2)
@ -398,7 +414,12 @@ static irqreturn_t sonic_interrupt(int irq, void *dev_id)
/* load CAM done */
if (status & SONIC_INT_LCD)
SONIC_WRITE(SONIC_ISR, SONIC_INT_LCD); /* clear the interrupt */
} while((status = SONIC_READ(SONIC_ISR) & SONIC_IMR_DEFAULT));
status = SONIC_READ(SONIC_ISR) & SONIC_IMR_DEFAULT;
} while (status);
spin_unlock_irqrestore(&lp->lock, flags);
return IRQ_HANDLED;
}

1
drivers/net/ethernet/natsemi/sonic.h
View File

@ -321,6 +321,7 @@ struct sonic_local {
unsigned int next_tx; /* next free TD */
struct device *device; /* generic device */
struct net_device_stats stats;
spinlock_t lock;
};
#define TX_TIMEOUT (3 * HZ)