Patch "rt2x00usb: do not anchor rx and tx urb's" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

rt2x00usb: do not anchor rx and tx urb's

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:

     rt2x00usb-do-not-anchor-rx-and-tx-urb-s.patch

and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Stanislaw Gruszka <[email protected]>
Date: Wed, 8 Feb 2017 12:18:09 +0100
Subject: rt2x00usb: do not anchor rx and tx urb's

From: Stanislaw Gruszka <[email protected]>

commit 93c7018ec16bb83399dd4db61c361a6d6aba0d5a upstream.

We might kill TX or RX urb during rt2x00usb_flush_entry(), what can cause anchor list corruption like shown below:

[ 2074.035633] WARNING: CPU: 2 PID: 14480 at lib/list_debug.c:33 __list_add+0xac/0xc0
[ 2074.035634] list_add corruption. prev->next should be next (ffff88020f362c28), but was dead000000000100. (prev=ffff8801d161bb70).
<snip>
[ 2074.035670] Call Trace:
[ 2074.035672]  [<ffffffff813bde47>] dump_stack+0x63/0x8c
[ 2074.035674]  [<ffffffff810a2231>] __warn+0xd1/0xf0
[ 2074.035676]  [<ffffffff810a22af>] warn_slowpath_fmt+0x5f/0x80
[ 2074.035678]  [<ffffffffa073855d>] ? rt2x00usb_register_write_lock+0x3d/0x60 [rt2800usb]
[ 2074.035679]  [<ffffffff813dbe4c>] __list_add+0xac/0xc0
[ 2074.035681]  [<ffffffff81591c6c>] usb_anchor_urb+0x4c/0xa0
[ 2074.035683]  [<ffffffffa07322af>] rt2x00usb_kick_rx_entry+0xaf/0x100 [rt2x00usb]
[ 2074.035684]  [<ffffffffa0732322>] rt2x00usb_clear_entry+0x22/0x30 [rt2x00usb]

To fix do not anchor TX and RX urb's, it is not needed as during shutdown we kill those urbs in rt2x00usb_free_entries().

---
 drivers/net/wireless/ralink/rt2x00/rt2x00usb.c |    4 ----
 1 file changed, 4 deletions(-)

@@ -319,10 +319,8 @@ static bool rt2x00usb_kick_tx_entry(stru
 			  entry->skb->data, length,
 			  rt2x00usb_interrupt_txdone, entry);
 
-	usb_anchor_urb(entry_priv->urb, rt2x00dev->anchor);
 	status = usb_submit_urb(entry_priv->urb, GFP_ATOMIC);
 	if (status) {
-		usb_unanchor_urb(entry_priv->urb);
 		if (status == -ENODEV)
 			clear_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags);
 		set_bit(ENTRY_DATA_IO_FAILED, &entry->flags);

@@ -410,10 +408,8 @@ static bool rt2x00usb_kick_rx_entry(stru
 			  entry->skb->data, entry->skb->len,
 			  rt2x00usb_interrupt_rxdone, entry);
 
-	usb_anchor_urb(entry_priv->urb, rt2x00dev->anchor);
 	status = usb_submit_urb(entry_priv->urb, GFP_ATOMIC);
 	if (status) {
-		usb_unanchor_urb(entry_priv->urb);
 		if (status == -ENODEV)
 			clear_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags);
 		set_bit(ENTRY_DATA_IO_FAILED, &entry->flags);

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/rt2x00-fix-incorrect-usage-of-config_rt2x00_lib_usb.patch queue-4.9/rt2x00usb-fix-anchor-initialization.patch queue-4.9/rt2x00usb-do-not-anchor-rx-and-tx-urb-s.patch