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Date: Thu, 6 Sep 2007 18:22:24 +0530 (IST)
From: Satyam Sharma <satyam@infradead.org>
To: Johannes Berg <johannes@sipsolutions.net>
cc: Herbert Xu <herbert@gondor.apana.org.au>,
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Subject: Re: BUG: scheduling while atomic: ifconfig/0x00000002/4170
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On Thu, 6 Sep 2007, Johannes Berg wrote:

> On Thu, 2007-09-06 at 16:23 +0800, Herbert Xu wrote:
> > On Thu, Sep 06, 2007 at 10:32:33AM +0530, Satyam Sharma wrote:
> > > 
> > > > > [  382.529041]  [<c02c8abc>] dev_close+0x24/0x67
> > > > > [  382.529052]  [<e01f402b>] ieee80211_master_stop+0x4a/0x6d [mac80211]
> > 
> > This is where the bug is.  You cannot call dev_close from an
> > atomic context as i33380211_master_stop does it within spin
> > locks.
> 
> Hah, I suspected as much but didn't have a chance to look yet. I had
> plans to replace that sub_if_list with an RCU list and not require the
> lock there, but that's far off.

Unless I missed something obvious (let me know if that's the case! :-)
an RCU-protected list would suffer the same fate. list_for_each_xxx_rcu()
must be under rcu_read_lock() which == preempt_disable() ...