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 for ath10k@lists.infradead.org; Mon, 26 May 2014 06:29:55 +0000
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Subject: Re: [PATCH v2 3/5] ath10k: drain tx before restarting hw
From: Johannes Berg <johannes@sipsolutions.net>
Date: Mon, 26 May 2014 08:29:26 +0200
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To: Michal Kazior <michal.kazior@tieto.com>
Cc: Kalle Valo <kvalo@qca.qualcomm.com>, linux-wireless <linux-wireless@vger.kernel.org>, "ath10k@lists.infradead.org" <ath10k@lists.infradead.org>

On Mon, 2014-05-26 at 07:48 +0200, Michal Kazior wrote:
> On 23 May 2014 15:03, Johannes Berg <johannes@sipsolutions.net> wrote:
> > On Fri, 2014-05-23 at 11:06 +0200, Michal Kazior wrote:
> >
> >> There's nothing wrong with other thread holding it. Actually that's
> >> the reason for this very check.
> >>
> >> The point is to prevent ath10k_drain_tx() being called while caller
> >> (current thread) holds conf_mutex. If it were to hold conf_mutex then
> >> cancel_work_sync() can deadlock as both workers it tries to stop try
> >> to get a hold of the lock too.
> >
> > That seems pointless - lockdep would warn you about that *anyway*
> > because cancel_work_sync() and friends have proper annotations. Try it
> > sometime :)
> 
> Does it splat every time or just by chance or after a deadlock?

Whenever you execute the second path for the first time.

johannes


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