Message-ID: <44F5BD23.3000209@fr.ibm.com>
Date: Wed, 30 Aug 2006 18:30:27 +0200
From: Cedric Le Goater <clg@fr.ibm.com>
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To: Andrew Morton <akpm@osdl.org>
CC: Sukadev Bhattiprolu <sukadev@us.ibm.com>, video4linux-list@redhat.com,
       Mauro Carvalho Chehab <mchehab@infradead.org>, kraxel@bytesex.org,
       haveblue@us.ibm.com, serue@us.ibm.com, Containers@lists.osdl.org,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH] kthread: saa7134-tvaudio.c
References: <20060829211555.GB1945@us.ibm.com> <20060829143902.a6aa2712.akpm@osdl.org>
In-Reply-To: <20060829143902.a6aa2712.akpm@osdl.org>
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Andrew Morton wrote:
> On Tue, 29 Aug 2006 14:15:55 -0700
> Sukadev Bhattiprolu <sukadev@us.ibm.com> wrote:
> 
>> Replace kernel_thread() with kthread_run() since kernel_thread()
>> is deprecated in drivers/modules. 
>>
>> Note that this driver, like a few others, allows SIGTERM. Not
>> sure if that is affected by conversion to kthread. Appreciate
>> any comments on that.
>>
> 
> hm, I think this driver needs more help.
> 
> - It shouldn't be using signals at all, really.  Signals are for
>   userspace IPC.  The kernel internally has better/richer/faster/tighter
>   ways of inter-thread communication.
> 
> - saa7134_tvaudio_fini()-versus-tvaudio_sleep() looks racy:
> 
> 	if (dev->thread.scan1 == dev->thread.scan2 && !dev->thread.shutdown) {
> 		if (timeout < 0) {
> 			set_current_state(TASK_INTERRUPTIBLE);
> 			schedule();
> 
>   If the wakeup happens after the test of dev->thread.shutdown, that sleep will
>   be permanent.
> 
> 
> So in general, yes, the driver should be converted to the kthread API -
> this is a requirement for virtualisation, but I forget why, and that's the
> "standard" way of doing it.
> 
> - The signal stuff should go away if at all possible.

The thread of this driver allows SIGTERM for some obscure reason. Not sure
why, I didn't find anything relying on it.

could we just remove the allow_signal() ?

C.
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