Message-ID: <5133DA12.8020907@oracle.com>
Date: Sun, 03 Mar 2013 18:17:38 -0500
From: Sasha Levin <sasha.levin@oracle.com>
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To: David Miller <davem@davemloft.net>
CC: samuel@sortiz.org, gregkh@linuxfoundation.org, jslaby@suse.cz,
        peter@hurleysoftware.com, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ircomm: release tty before sleeping potentially indefintely
References: <1362350153-26225-1-git-send-email-sasha.levin@oracle.com> <20130303.174739.1195645942179862011.davem@davemloft.net>
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On 03/03/2013 05:47 PM, David Miller wrote:
> From: Sasha Levin <sasha.levin@oracle.com>
> Date: Sun,  3 Mar 2013 17:35:53 -0500
> 
>> ircomm_tty_block_til_ready would hold tty lock while blocking. Since the sleep
>> might take a long time we can prevent other processes from accessing the tty,
>> causing hung tasks and a dead tty.
>>
>> Diagnosed-by: Peter Hurley <peter@hurleysoftware.com>
>> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
> 
> But then you invalidate all of the tty state tests made under
> the lock at the beginning of this function, before enterring
> the loop.  If you drop the lock, those pieces of state could
> change.
> 
> I'm not applying this.

I'm unsure. A similar patch was applied back in 2010 that does the same thing
to a bunch of drivers, including the core tty code (e142a31da "tty: release
BTM while sleeping in block_til_ready").

This IR code looks very much like tty_port_block_til_ready() where it was
okay to do that change, so I should be the same with ircomm_tty_block_til_ready.


Thanks,
Sasha


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