[PATCH] lance.c - dev_kfree_skb() then reference skb->len

[PATCH] lance.c - dev_kfree_skb() then reference skb->len

[Eli Carter]

[-- Attachment #1: Type: text/plain, Size: 668 bytes --]

Greetings all,

Patch is against 2.2.17, drivers/net/lance.c.
I believe this to be "obviously correct," but please correct me if I'm
wrong.
This moves a reference to skb->len to before the possible
dev_kfree_skb(skb) call.  Though it appears to work as is, I suspect it
is incorrect.

Please apply or let me know why.

Eli

ps.  It's an attachment rather than inline because I can't seem to get
Netscape (4.71) to do that without replacing tabs with spaces.  Grr.

--------------------. "To the systems programmer, users and applications
Eli Carter          | serve only to provide a test load."
eli.carter@inet.com `---------------------------------- (random fortune)

[-- Attachment #2: lance.c.diff --]
[-- Type: text/plain, Size: 561 bytes --]

--- lance.c.2.2.17	Mon Nov 13 12:13:11 2000
+++ lance.c	Tue Nov 28 11:46:16 2000
@@ -926,6 +926,8 @@
 
 	lp->tx_ring[entry].misc = 0x0000;
 
+	lp->stats.tx_bytes += skb->len;
+
 	/* If any part of this buffer is >16M we must copy it to a low-memory
 	   buffer. */
 	if ((u32)virt_to_bus(skb->data) + skb->len > 0x01000000) {
@@ -941,7 +943,6 @@
 		lp->tx_ring[entry].base = ((u32)virt_to_bus(skb->data) & 0xffffff) | 0x83000000;
 	}
 	lp->cur_tx++;
-	lp->stats.tx_bytes += skb->len;
 
 	/* Trigger an immediate send poll. */
 	outw(0x0000, ioaddr+LANCE_ADDR);

Re: [PATCH] lance.c - dev_kfree_skb() then reference skb->len

[Donald Becker]

On Tue, 28 Nov 2000, Eli Carter wrote:

> Patch is against 2.2.17, drivers/net/lance.c.
> I believe this to be "obviously correct," but please correct me if I'm
> wrong.
> This moves a reference to skb->len to before the possible
> dev_kfree_skb(skb) call.  Though it appears to work as is, I suspect it
> is incorrect.

This patch looks reasonable.

Perhaps it would be better to have the driver retain the skbuff until the
transmit succeeds, and only then add the length to the stats.  But this
specific bug is related the ISA bounce buffer code.  Any ISA card is in
the "legacy" category, so it's better to make minimal change needed to
correct the obvious potential problem.



Donald Becker				becker@scyld.com
Scyld Computing Corporation		http://www.scyld.com
410 Severn Ave. Suite 210		Second Generation Beowulf Clusters
Annapolis MD 21403			410-990-9993

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