From: Johannes Berg <johannes@sipsolutions.net>
To: Ben Greear <greearb@candelatech.com>
Cc: "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Subject: Re: deadlock on sdata->u.mgd.mtx between worker thread an 'ip'?
Date: Tue, 05 Oct 2010 10:43:06 +0200 [thread overview]
Message-ID: <1286268186.3641.10.camel@jlt3.sipsolutions.net> (raw)
In-Reply-To: <4CAAB75A.3050309@candelatech.com>
On Mon, 2010-10-04 at 22:27 -0700, Ben Greear wrote:
> I think the deadlock might be between kworker and ip, on the
> sdata->u.mgd.mtx v/s iflist_mtx lock. It seems both processes
> have ifmgd->mtx held, and worker is trying to grab it again but
> blocks.
>
> I think maybe the ip process has locked a different sdata than
> 'forsdata', so that is why this nested lock attempt by the worker thread
> to all of the !forsdata objects blocks?
>
> void ieee80211_recalc_smps(struct ieee80211_local *local,
> struct ieee80211_sub_if_data *forsdata)
> ...
> if (sdata != forsdata) {
> /*
> * This nested is ok -- we are holding the iflist_mtx
> * so can't get here twice or so. But it's required
> * since normally we acquire it first and then the
> * iflist_mtx.
> */
> mutex_lock_nested(&sdata->u.mgd.mtx, SINGLE_DEPTH_NESTING);
> count += check_mgd_smps(&sdata->u.mgd, &smps_mode);
> mutex_unlock(&sdata->u.mgd.mtx);
> } else
I just debugged the same based on your other mail ...
johannes
prev parent reply other threads:[~2010-10-05 8:43 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-05 5:27 deadlock on sdata->u.mgd.mtx between worker thread an 'ip'? Ben Greear
2010-10-05 8:43 ` Johannes Berg [this message]
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