netdev - Re: [PATCH] 3c507.c: remove unused NULL pointer check

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Date:	Mon, 21 Dec 2009 17:56:39 +0100
From:	Oliver Hartkopp <socketcan@...tkopp.net>
To:	Alexander Strakh <strakh@...ras.ru>
CC:	Bartlomiej Zolnierkiewicz <bzolnier@...il.com>,
	Donald Becker <becker@...ld.com>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] 3c507.c: remove unused NULL pointer check

Alexander Strakh wrote:
> 	In driver drivers/net/3c507.c in function Iirqreturn_t el16_interrupt:
> 1. If in line 555 dev = NULL then we goto line 556
> 2. In line 556 we have null dereference because pr_err called with dev->name 
> in third parameter.
>  555        if (dev == NULL) {
>  556                pr_err("%s: net_interrupt(): irq %d for unknown device.
> \n",
>  557                        dev->name, irq);
>  558                return IRQ_NONE;
>  559        }
> 
> Found by Linux Device Drivers Verification (Svace detector)
> 
> Remove unused NULL pointer check.

You are obviously doing more than that ...

> 
> Signed-off-by: Alexander Strakh <strakh@...ras.ru>
> 
> ---
> diff --git a/./0000/drivers/net/3c507.c b/./moder/drivers/net/3c507.c
> index fbc2311..3bfb3dd 100644
> --- a/./0000/drivers/net/3c507.c
> +++ b/./moder/drivers/net/3c507.c
> @@ -552,12 +552,6 @@ static irqreturn_t el16_interrupt(int irq, void *dev_id)
>  	ushort ack_cmd = 0;
>  	void __iomem *shmem;
>  
> -	if (dev == NULL) {
> -		pr_err("%s: net_interrupt(): irq %d for unknown device.\n",
> -			dev->name, irq);

You are changing real funcionality here!

If you want to fix it, fix the pr_err() but do not remove the "return
IRQ_NONE" entirely.

This looks like an introduction of a bug.

Regards,
Oliver


> -		return IRQ_NONE;
> -	}
> -

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