linux-kernel - Re: [PATCH] Xilinx: hwicap: cleanup

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Message-ID: <47C2796F.2070601@gmail.com>
Date:	Mon, 25 Feb 2008 09:16:47 +0100
From:	Jiri Slaby <jirislaby@...il.com>
To:	Stephen Neuendorffer <stephen.neuendorffer@...inx.com>
CC:	Grant Likely <grant.likely@...retlab.ca>, linuxppc-dev@...abs.org,
	git-dev <git-dev@...inx.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Xilinx: hwicap: cleanup

On 02/25/2008 12:21 AM, Stephen Neuendorffer wrote:
>>>  @@ -549,8 +556,7 @@ static int hwicap_release(struct inode *inode,
> struct file *file)
>>>         int i;
>>>         int status = 0;
>>>
>>>  -       if (down_interruptible(&drvdata->sem))
>>>  -               return -ERESTARTSYS;
>>>  +       mutex_lock(&drvdata->sem);
>> Why not mutex_lock_interruptible()? (goes for all cases of
> mutex_lock())
> 
> It's not clear to me how to get 'correct' behavior in these functions if
> the interrupt happens.  For instance in probe/setup, if the mutex_lock
> is interrupted, it doesn't appear that there is anything to do other
> than return an error code that no device is present?  I think this was
> suggested by Jiri...

Yeah, since ERESTARTSYS would be ignored from f_op->release (see __fput()), 
drv->probe (see really_probe() and probe_failed label); not even talking about 
void return value functions. In those cases, the device won't be de/initialized 
and might result in unwanted behaviour (multiple modprobes for one device, 
rmmod/insmod need if you hit the path in release etc.).
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