[TG3]: Convert to non-LLTX
Herbert Xu pointed out that it is unsafe to call netif_tx_disable()
from LLTX drivers because it uses dev->xmit_lock to synchronize
whereas LLTX drivers use private locks.
Convert tg3 to non-LLTX to fix this issue. tg3 is a lockless driver
where hard_start_xmit and tx completion handling can run concurrently
under normal conditions. A tx_lock is only needed to prevent
netif_stop_queue and netif_wake_queue race condtions when the queue
is full.
So whether we use LLTX or non-LLTX, it makes practically no
difference.
Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c
index 542d4c3..b2ddd45 100644
--- a/drivers/net/tg3.c
+++ b/drivers/net/tg3.c
@@ -3759,14 +3759,11 @@
len = skb_headlen(skb);
- /* No BH disabling for tx_lock here. We are running in BH disabled
- * context and TX reclaim runs via tp->poll inside of a software
+ /* We are running in BH disabled context with netif_tx_lock
+ * and TX reclaim runs via tp->poll inside of a software
* interrupt. Furthermore, IRQ processing runs lockless so we have
* no IRQ context deadlocks to worry about either. Rejoice!
*/
- if (!spin_trylock(&tp->tx_lock))
- return NETDEV_TX_LOCKED;
-
if (unlikely(TX_BUFFS_AVAIL(tp) <= (skb_shinfo(skb)->nr_frags + 1))) {
if (!netif_queue_stopped(dev)) {
netif_stop_queue(dev);
@@ -3775,7 +3772,6 @@
printk(KERN_ERR PFX "%s: BUG! Tx Ring full when "
"queue awake!\n", dev->name);
}
- spin_unlock(&tp->tx_lock);
return NETDEV_TX_BUSY;
}
@@ -3858,15 +3854,16 @@
tw32_tx_mbox((MAILBOX_SNDHOST_PROD_IDX_0 + TG3_64BIT_REG_LOW), entry);
tp->tx_prod = entry;
- if (TX_BUFFS_AVAIL(tp) <= (MAX_SKB_FRAGS + 1)) {
+ if (unlikely(TX_BUFFS_AVAIL(tp) <= (MAX_SKB_FRAGS + 1))) {
+ spin_lock(&tp->tx_lock);
netif_stop_queue(dev);
if (TX_BUFFS_AVAIL(tp) > TG3_TX_WAKEUP_THRESH)
netif_wake_queue(tp->dev);
+ spin_unlock(&tp->tx_lock);
}
out_unlock:
mmiowb();
- spin_unlock(&tp->tx_lock);
dev->trans_start = jiffies;
@@ -3885,14 +3882,11 @@
len = skb_headlen(skb);
- /* No BH disabling for tx_lock here. We are running in BH disabled
- * context and TX reclaim runs via tp->poll inside of a software
+ /* We are running in BH disabled context with netif_tx_lock
+ * and TX reclaim runs via tp->poll inside of a software
* interrupt. Furthermore, IRQ processing runs lockless so we have
* no IRQ context deadlocks to worry about either. Rejoice!
*/
- if (!spin_trylock(&tp->tx_lock))
- return NETDEV_TX_LOCKED;
-
if (unlikely(TX_BUFFS_AVAIL(tp) <= (skb_shinfo(skb)->nr_frags + 1))) {
if (!netif_queue_stopped(dev)) {
netif_stop_queue(dev);
@@ -3901,7 +3895,6 @@
printk(KERN_ERR PFX "%s: BUG! Tx Ring full when "
"queue awake!\n", dev->name);
}
- spin_unlock(&tp->tx_lock);
return NETDEV_TX_BUSY;
}
@@ -4039,15 +4032,16 @@
tw32_tx_mbox((MAILBOX_SNDHOST_PROD_IDX_0 + TG3_64BIT_REG_LOW), entry);
tp->tx_prod = entry;
- if (TX_BUFFS_AVAIL(tp) <= (MAX_SKB_FRAGS + 1)) {
+ if (unlikely(TX_BUFFS_AVAIL(tp) <= (MAX_SKB_FRAGS + 1))) {
+ spin_lock(&tp->tx_lock);
netif_stop_queue(dev);
if (TX_BUFFS_AVAIL(tp) > TG3_TX_WAKEUP_THRESH)
netif_wake_queue(tp->dev);
+ spin_unlock(&tp->tx_lock);
}
out_unlock:
mmiowb();
- spin_unlock(&tp->tx_lock);
dev->trans_start = jiffies;
@@ -11284,7 +11278,6 @@
SET_MODULE_OWNER(dev);
SET_NETDEV_DEV(dev, &pdev->dev);
- dev->features |= NETIF_F_LLTX;
#if TG3_VLAN_TAG_USED
dev->features |= NETIF_F_HW_VLAN_TX | NETIF_F_HW_VLAN_RX;
dev->vlan_rx_register = tg3_vlan_rx_register;
diff --git a/drivers/net/tg3.h b/drivers/net/tg3.h
index 35669e1..8209da5 100644
--- a/drivers/net/tg3.h
+++ b/drivers/net/tg3.h
@@ -2074,12 +2074,22 @@
/* SMP locking strategy:
*
- * lock: Held during all operations except TX packet
- * processing.
+ * lock: Held during reset, PHY access, timer, and when
+ * updating tg3_flags and tg3_flags2.
*
- * tx_lock: Held during tg3_start_xmit and tg3_tx
+ * tx_lock: Held during tg3_start_xmit and tg3_tx only
+ * when calling netif_[start|stop]_queue.
+ * tg3_start_xmit is protected by netif_tx_lock.
*
* Both of these locks are to be held with BH safety.
+ *
+ * Because the IRQ handler, tg3_poll, and tg3_start_xmit
+ * are running lockless, it is necessary to completely
+ * quiesce the chip with tg3_netif_stop and tg3_full_lock
+ * before reconfiguring the device.
+ *
+ * indirect_lock: Held when accessing registers indirectly
+ * with IRQ disabling.
*/
spinlock_t lock;
spinlock_t indirect_lock;