Bug 42818

Summary:	r8712u locking problem introduced by commit a5ee652
Product:	Drivers	Reporter:	Larry Finger (Larry.Finger)
Component:	Staging	Assignee:	Larry Finger (Larry.Finger)
Status:	RESOLVED CODE_FIX
Severity:	high	CC:	florian
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	3.2.0 and later	Subsystem:
Regression:	Yes	Bisected commit-id:
Attachments:	Patch to fix locking problem when using wicd

Description Larry Finger 2012-02-24 18:15:05 UTC

In kernels 3.2.0 and later, the staging driver r8712u does not work when wicd is used to control wireless networking. The problem was bisected to commit a5ee652. The logs show a locking problem in wpa_supplicant, as shown below. 

kernel: [  480.380063] wpa_supplicant  D ffff88002ec40b60     0  5092      1 0x00000000
kernel: [  480.380067]  ffff88006b307ca8 0000000000000082 ffffffff8164e440 ffffea00004d81f0
kernel: [  480.380070]  ffff88002ec407c0 ffff88006b307fd8 ffff88006b307fd8 ffff88006b307fd8
kernel: [  480.380073]  ffff88006b278680 ffff88002ec407c0 ffff88006d437200 0000000000000000
kernel: [  480.380076] Call Trace:
kernel: [  480.380083]  [<ffffffff813d117a>] schedule+0x3a/0x50
kernel: [  480.380086]  [<ffffffff813d1f75>] __mutex_lock_slowpath+0xe5/0x170
kernel: [  480.380088]  [<ffffffff813d1b0d>] mutex_lock+0x1d/0x40
kernel: [  480.380091]  [<ffffffff81336d40>] rtnl_lock+0x10/0x20
kernel: [  480.380094]  [<ffffffff813b5452>] wext_handle_ioctl+0x62/0x250
kernel: [  480.380097]  [<ffffffff8132bfeb>] dev_ioctl+0xdb/0x5f0
kernel: [  480.380101]  [<ffffffff810f943f>] ? tlb_finish_mmu+0xf/0x40
kernel: [  480.380105]  [<ffffffff81312ddd>] sock_ioctl+0x10d/0x2d0
kernel: [  480.380108]  [<ffffffff8112c5be>] do_vfs_ioctl+0x8e/0x510
kernel: [  480.380111]  [<ffffffff8112cad1>] sys_ioctl+0x91/0xa0
kernel: [  480.380113]  [<ffffffff813dadd2>] system_call_fastpath+0x16/0x1b

Comment 1 Larry Finger 2012-02-24 18:42:53 UTC

Created attachment 72480 [details]
Patch to fix locking problem when using wicd

Comment 2 Greg Kroah-Hartman 2012-02-24 18:51:58 UTC

Why are you using bugzilla for patches, please just use the mailing list, we can't do anything with patches here, you know better :)

Comment 3 Larry Finger 2012-02-24 19:09:39 UTC

Of course I know better. Putting it here was just in case some other user runs across the problem before I push the "real" patch to you. I'm waiting for some testing - I only found the bug 3 hours ago.

Comment 4 Florian Mickler 2012-04-04 15:02:11 UTC

A patch referencing this bug report has been merged in Linux v3.4-rc1:

commit 9f4bc8cf3fe750ed093856a5f5d41c11cc12ad22
Author: Larry Finger <Larry.Finger@lwfinger.net>
Date:   Sat Feb 25 18:10:20 2012 -0600

    staging: r8712u: Fix regression introduced by commit a5ee652