Date: Wed, 16 May 2007 22:51:29 -0700 (PDT)
Message-Id: <20070516.225129.74748893.davem@davemloft.net>
To: ssatyam@cse.iitk.ac.in
Cc: akpm@linux-foundation.org, marcel@holtmann.org, jikos@jikos.cz,
       gregkh@suse.de, jeremy@goop.org, maxk@qualcomm.com, clg@fr.ibm.com,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH] bluetooth: fix locking in hci_sock_dev_event()
From: David Miller <davem@davemloft.net>
In-Reply-To: <Pine.LNX.4.64.0705171106550.9262@cselinux1.cse.iitk.ac.in>
References: <Pine.LNX.4.64.0705171106550.9262@cselinux1.cse.iitk.ac.in>
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From: Satyam Sharma <ssatyam@cse.iitk.ac.in>
Date: Thu, 17 May 2007 11:13:36 +0530 (IST)

> [PATCH] bluetooth: fix locking in hci_sock_dev_event()
> 
> We presently use lock_sock() to acquire a lock on a socket in
> hci_sock_dev_event(), but this goes BUG because lock_sock()
> can sleep and we're already holding a read-write spinlock at
> that point. So, we must use the non-sleeping BH version,
> bh_lock_sock().
> 
> However, hci_sock_dev_event() is called from user context and
> hence using simply bh_lock_sock() will deadlock against a
> concurrent softirq that tries to acquire a lock on the same
> socket. Hence, disabling BH's before acquiring the socket lock
> and enable them afterwards, is the proper solution to fix
> socket locking in hci_sock_dev_event().
> 
> Cc: David Miller <davem@davemloft.net>
> Signed-off-by: Satyam Sharma <ssatyam@cse.iitk.ac.in>
> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
> Signed-off-by: Jiri Kosina <jkosina@suse.cz>

Thanks I'll merge this in.
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