Subject: Re: BUG: bad unlock balance detected! e1000e

From: Andrew Morton <[email-masked]>
Date: Tue, 9 Dec 2008 15:08:01 -0800

On Tue, 9 Dec 2008 12:03:37 +0100
Frederik Deweerdt <[email-masked]> wrote:

> It some error checking is missing in e1000e: debug contention on NVM
> SWFLAG
> On Mon, Dec 08, 2008 at 12:24:09PM +0100, Zdenek Kabelac wrote:
> > Hi
> > 
> > During occasional scan of message log - I've found out this BUG which
> > happened on Dec3 with the -rc7 from that day.
> > (So if it's now fixed in current git feel free to ignore :))
> > 
> > My machine T61 - C2D, 2GB, 64bit kernel - message appeared during
> > shutdown and was actually not noticed by me...
> > 
> > 
> > NetworkManager: <WARN>  nm_signal_handler(): Caught signal 15,
> > shutting down normally.
> > NetworkManager: <info>  (eth0): now unmanaged
> > NetworkManager: <info>  (eth0): device state change: 3 -> 1
> > NetworkManager: <info>  (eth0): cleaning up...
> > NetworkManager: <info>  (eth0): taking down device.
> > 
> > =====================================
> > [ BUG: bad unlock balance detected! ]
> > -------------------------------------

(top-posting repaired.  Please don't do that!!!).

> Hello Zdenek,
> 
> This could be due to 717d438d1fde94decef874b9808379d1f4523453
>     "e1000e: debug contention on NVM SWFLAG"
> Error handling is missing from e1000_reset_hw_ich8lan so it may happen
> that we don't acquire the nvm_mutex if the card times out.
> 
> Adding Thomas to CC.

yup.  2.6.27 needs fixing also.

Like this?

From: Andrew Morton <[email-masked]>

=====================================
[ BUG: bad unlock balance detected! ]
-------------------------------------

A regression added by 717d438d1fde94decef874b9808379d1f4523453 ("e1000e:
debug contention on NVM SWFLAG").

Reported-by: "Zdenek Kabelac" <[email-masked]>
Cc: Frederik Deweerdt <[email-masked]>
Cc: Thomas Gleixner <[email-masked]>
Cc: Jesse Brandeburg <[email-masked]>
Cc: "David S. Miller" <[email-masked]>
Cc: <[email-masked]>
Signed-off-by: Andrew Morton <[email-masked]>
---

 drivers/net/e1000e/ich8lan.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff -puN drivers/net/e1000e/ich8lan.c~drivers-net-e1000e-ich8lanc-fix-locking drivers/net/e1000e/ich8lan.c
--- a/drivers/net/e1000e/ich8lan.c~drivers-net-e1000e-ich8lanc-fix-locking
+++ a/drivers/net/e1000e/ich8lan.c
@@ -400,6 +400,7 @@ static s32 e1000_acquire_swflag_ich8lan(
 {
 	u32 extcnf_ctrl;
 	u32 timeout = PHY_CFG_TIMEOUT;
+	s32 ret = 0;
 
 	might_sleep();
 
@@ -427,11 +428,11 @@ static s32 e1000_acquire_swflag_ich8lan(
 		extcnf_ctrl &= ~E1000_EXTCNF_CTRL_SWFLAG;
 		ew32(EXTCNF_CTRL, extcnf_ctrl);
 		nvm_owner = -1;
-		mutex_unlock(&nvm_mutex);
-		return -E1000_ERR_CONFIG;
+		ret = -E1000_ERR_CONFIG;
 	}
 
-	return 0;
+	mutex_unlock(&nvm_mutex);
+	return ret;
 }
 
 /**
_