This driver's 4-packet deep TX queue is too sensible to the "careless" callers
ignoring its state (like netpoll in trapped mode), so add "queue full" check at
the start of the hard_start_xmit() method (only under #ifndef RTL8139_NDEBUG,
otherwise the queue will get stuck once dirty pointer gets out of sync); switch
to using appropriate mnemonics for the return values while at it.
Also, the out-of-sync dirty pointer check is misplaced in rtl8139_tx_interrupt()
which causes TX descriptors to be inspected more than once in case the pointer
really gets out-of-sync (and incrementing the dirty pointer always by 4 is just
not enough, e.g. KGDBoE managed to stuff 20+ extra buffers into the queue) --
place it before the loop and limit the loop to only look through 4 descriptors
at most, so that already overwritten descriptors are just not counted.
Signed-off-by: Sergei Shtylyov <[EMAIL PROTECTED]>
---
drivers/net/8139too.c | 31 ++++++++++++++++++++-----------
1 files changed, 20 insertions(+), 11 deletions(-)
Index: linux-2.6/drivers/net/8139too.c
===================================================================
--- linux-2.6.orig/drivers/net/8139too.c
+++ linux-2.6/drivers/net/8139too.c
@@ -90,7 +90,7 @@
*/
#define DRV_NAME "8139too"
-#define DRV_VERSION "0.9.28"
+#define DRV_VERSION "0.9.31"
#include <linux/module.h>
@@ -1708,6 +1708,13 @@ static int rtl8139_start_xmit (struct sk
unsigned int len = skb->len;
unsigned long flags;
+#ifndef RTL8139_NDEBUG
+ if (unlikely((tp->cur_tx - tp->dirty_tx) >= NUM_TX_DESC)) {
+ printk(KERN_ERR "%s: TX queue full!\n", dev->name);
+ return NETDEV_TX_BUSY;
+ }
+#endif
+
/* Calculate the next Tx descriptor entry. */
entry = tp->cur_tx % NUM_TX_DESC;
@@ -1720,7 +1727,7 @@ static int rtl8139_start_xmit (struct sk
} else {
dev_kfree_skb(skb);
tp->stats.tx_dropped++;
- return 0;
+ return NETDEV_TX_OK;
}
spin_lock_irqsave(&tp->lock, flags);
@@ -1740,7 +1747,7 @@ static int rtl8139_start_xmit (struct sk
printk (KERN_DEBUG "%s: Queued Tx packet size %u to slot %d.\n",
dev->name, len, entry);
- return 0;
+ return NETDEV_TX_OK;
}
@@ -1755,6 +1762,16 @@ static void rtl8139_tx_interrupt (struct
dirty_tx = tp->dirty_tx;
tx_left = tp->cur_tx - dirty_tx;
+
+#ifndef RTL8139_NDEBUG
+ if (unlikely(tx_left > NUM_TX_DESC)) {
+ printk(KERN_ERR "%s: Out-of-sync dirty pointer, %ld vs. %ld.\n",
+ dev->name, dirty_tx, tp->cur_tx);
+ tx_left = NUM_TX_DESC;
+ dirty_tx = tp->cur_tx - NUM_TX_DESC;
+ }
+#endif /* RTL8139_NDEBUG */
+
while (tx_left > 0) {
int entry = dirty_tx % NUM_TX_DESC;
int txstatus;
@@ -1797,14 +1814,6 @@ static void rtl8139_tx_interrupt (struct
tx_left--;
}
-#ifndef RTL8139_NDEBUG
- if (tp->cur_tx - dirty_tx > NUM_TX_DESC) {
- printk (KERN_ERR "%s: Out-of-sync dirty pointer, %ld vs.
%ld.\n",
- dev->name, dirty_tx, tp->cur_tx);
- dirty_tx += NUM_TX_DESC;
- }
-#endif /* RTL8139_NDEBUG */
-
/* only wake the queue if we did work, and the queue is stopped */
if (tp->dirty_tx != dirty_tx) {
tp->dirty_tx = dirty_tx;
-
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