netdev - Re: igb_down from bottom half context

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Date:	Wed, 6 Mar 2013 17:38:06 +0000
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	ratheesh kannoth <ratheesh.ksz@...il.com>
CC:	<e1000-devel@...ts.sourceforge.net>, <netdev@...r.kernel.org>,
	linux-newbie <linux-newbie@...r.kernel.org>,
	Alexander Duyck <alexander.h.duyck@...el.com>
Subject: Re: igb_down from bottom half context

On Wed, 2013-03-06 at 09:38 +0530, ratheesh kannoth wrote:
> I  have kernel timer which  check for flag.
> 
> if(flag ) {
>           igb_down(adapter);
>  } else {
>          igb_up(adapter);
>  }
> 
> 
> I could see a kernel crash; because  there are a lot of  msleep() in
> igb_down function.
> 
> #define msleep(x)    do { set_current_state(TASK_UNINTERRUPTIBLE); \
>                                 schedule_timeout((x * HZ)/1000 + 2); \
>                               } while (0)
> 
> sleep() is called from bottom half context; this is the cause of kernel crash.
> 
> 1) Since timer call back dont have process context associated with it;
> i think , "current" points to the last preempted task ?
> 2) How can i introduce delays in interrupt context to avoid the kernel
> crash. mdelay()  will work ?
> 3) is there any better mechanism to do this job ?

Use a work item and schedule_work().

Ben.

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

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