Re: [PATCH] rt2x00: rt2800: fix zeroing skb structure

On Sat, 30 Jul 2011, Justin Piszcz wrote:

On Sat, 30 Jul 2011, Stanislaw Gruszka wrote:

quoted

We should clear skb->data not skb itself. Bug was introduced by:
commit 0b8004aa12d13ec750d102ba4082a95f0107c649 "rt2x00: Properly
reserve room for descriptors in skbs".

Cc: stable@kernel.org # 2.6.36+
Signed-off-by: Stanislaw Gruszka <redacted>
---
drivers/net/wireless/rt2x00/rt2800lib.c |    3 +--
1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/rt2x00/rt2800lib.c 

b/drivers/net/wireless/rt2x00/rt2800lib.c
index 75d2c6c..f94d669 100644

--- a/drivers/net/wireless/rt2x00/rt2800lib.c
+++ b/drivers/net/wireless/rt2x00/rt2800lib.c

@@ -703,8 +703,7 @@ void rt2800_write_beacon(struct queue_entry *entry, 

struct txentry_desc *txdesc)
	/*
	 * Add space for the TXWI in front of the skb.
	 */
-	skb_push(entry->skb, TXWI_DESC_SIZE);
-	memset(entry->skb, 0, TXWI_DESC_SIZE);
+	memset(skb_push(entry->skb, TXWI_DESC_SIZE), 0, TXWI_DESC_SIZE);

	/*
	 * Register descriptor details in skb frame descriptor.
-- 
1.7.4

Hi,

Testing w/ Linux kernel 3.0:

# patch -p1 < ../patch3
patching file drivers/net/wireless/rt2x00/rt2800lib.c
Hunk #1 succeeded at 784 (offset 81 lines).

Compiled/installed.

Will reboot shortly, need to run a backup first, thanks.

Justin.

Hi,

Patched, its working, latency is MUCH better than before the patch!

PING atomw.internal.lan (192.168.0.2) 56(84) bytes of data.
64 bytes from atomw.internal.lan (192.168.0.2): icmp_req=1 ttl=64 time=0.535 ms
64 bytes from atomw.internal.lan (192.168.0.2): icmp_req=2 ttl=64 time=0.589 ms
64 bytes from atomw.internal.lan (192.168.0.2): icmp_req=3 ttl=64 time=48.8 ms
64 bytes from atomw.internal.lan (192.168.0.2): icmp_req=4 ttl=64 time=1.14 ms
64 bytes from atomw.internal.lan (192.168.0.2): icmp_req=5 ttl=64 time=64.5 ms
64 bytes from atomw.internal.lan (192.168.0.2): icmp_req=6 ttl=64 time=0.582 ms
64 bytes from atomw.internal.lan (192.168.0.2): icmp_req=7 ttl=64 time=80.6 ms
64 bytes from atomw.internal.lan (192.168.0.2): icmp_req=8 ttl=64 time=51.9 ms
64 bytes from atomw.internal.lan (192.168.0.2): icmp_req=9 ttl=64 time=35.5 ms
64 bytes from atomw.internal.lan (192.168.0.2): icmp_req=10 ttl=64 time=0.614 ms
64 bytes from atomw.internal.lan (192.168.0.2): icmp_req=11 ttl=64 time=0.497 ms
64 bytes from atomw.internal.lan (192.168.0.2): icmp_req=12 ttl=64 time=41.5 ms

$ uptime
  10:19:18 up 5 min,  2 users,  load average: 1.32, 1.02, 0.47

It hasn't crashed yet, if you don't hear from me/stating it has crashed again,
then you can assume its stable, I'll let you know if anything happens.

Justin.