linux-kernel - Re: BUG: bad unlock balance detected! e1000e

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Message-ID: <20081209234346.GB7394@gambetta>
Date:	Wed, 10 Dec 2008 00:43:46 +0100
From:	Frederik Deweerdt <frederik.deweerdt@...og.eu>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	zdenek.kabelac@...il.com, linux-kernel@...r.kernel.org,
	tglx@...utronix.de, netdev@...r.kernel.org,
	Jesse Brandeburg <jesse.brandeburg@...el.com>,
	"David S. Miller" <davem@...emloft.net>, stable@...nel.org
Subject: Re: BUG: bad unlock balance detected! e1000e

On Tue, Dec 09, 2008 at 03:08:01PM -0800, Andrew Morton wrote:
> On Tue, 9 Dec 2008 12:03:37 +0100
> Frederik Deweerdt <frederik.deweerdt@...og.eu> 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!!!).
Yep, sorry.
> 
> > 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?
I don't think so, e1000_acquire_swflag_ich8lan() locks and
e1000_release_swflag_ich8lan() unlocks. I think it is more along the
lines of:


diff --git a/drivers/net/e1000e/ich8lan.c b/drivers/net/e1000e/ich8lan.c
index 523b971..f971b83 100644
--- a/drivers/net/e1000e/ich8lan.c
+++ b/drivers/net/e1000e/ich8lan.c
@@ -1892,7 +1892,13 @@ static s32 e1000_reset_hw_ich8lan(struct e1000_hw *hw)
 		 */
 		ctrl |= E1000_CTRL_PHY_RST;
 	}
+
 	ret_val = e1000_acquire_swflag_ich8lan(hw);
+	if (ret_val) {
+		hw_dbg(hw, "Failed to acquire NVM swflag");
+		return ret_val;
+	}
+
 	hw_dbg(hw, "Issuing a global reset to ich8lan");
 	ew32(CTRL, (ctrl | E1000_CTRL_RST));
 	msleep(20);


But I'm not sure we should cancel the ongoing reset if the card times
out... 


Regards,
Frederik

> 
> From: Andrew Morton <akpm@...ux-foundation.org>
> 
> =====================================
> [ BUG: bad unlock balance detected! ]
> -------------------------------------
> 
> A regression added by 717d438d1fde94decef874b9808379d1f4523453 ("e1000e:
> debug contention on NVM SWFLAG").
> 
> Reported-by: "Zdenek Kabelac" <zdenek.kabelac@...il.com>
> Cc: Frederik Deweerdt <frederik.deweerdt@...og.eu>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Jesse Brandeburg <jesse.brandeburg@...el.com>
> Cc: "David S. Miller" <davem@...emloft.net>
> Cc: <stable@...nel.org>
> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
> ---
> 
>  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;
>  }
>  
>  /**
> _
> 
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