linux-kernel - Re: [PATCH 7/9] net: macb: avoid uninitialized variables

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Message-ID: <56A8EA9F.6070404@atmel.com>
Date:	Wed, 27 Jan 2016 17:04:47 +0100
From:	Nicolas Ferre <nicolas.ferre@...el.com>
To:	Arnd Bergmann <arnd@...db.de>,
	"David S. Miller" <davem@...emloft.net>
CC:	<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 7/9] net: macb: avoid uninitialized variables

Le 27/01/2016 16:51, Nicolas Ferre a écrit :
> Le 27/01/2016 15:04, Arnd Bergmann a écrit :
>> The macb_clk_init function returns three clock pointers, unless
>> the it fails to get the first ones. We correctly handle the
>> failure case by propagating the error from macb_probe, but
>> gcc does not realize this and incorrectly warns about a later
>> use of those:
>>
>> In file included from /git/arm-soc/drivers/net/ethernet/cadence/macb.c:12:0:
>> drivers/net/ethernet/cadence/macb.c: In function 'macb_probe':
>> include/linux/clk.h:484:2: error: 'tx_clk' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>>   clk_disable(clk);
>>   ^
>> drivers/net/ethernet/cadence/macb.c:2822:28: note: 'tx_clk' was declared here
>>   struct clk *pclk, *hclk, *tx_clk;
>>                             ^
>> In file included from /git/arm-soc/drivers/net/ethernet/cadence/macb.c:12:0:
>> include/linux/clk.h:484:2: error: 'hclk' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>>   clk_disable(clk);
>>   ^
>> drivers/net/ethernet/cadence/macb.c:2822:21: note: 'hclk' was declared here
>>   struct clk *pclk, *hclk, *tx_clk;
>>                      ^
>>
>> This shuts up the misleading warnings by ensuring that the
>> macb_clk_init() always stores something into all three pointers.
>>
>> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> 
> Okay Arnd, thanks!
> 
> Acked-by: Nicolas Ferre <nicolas.ferre@...el.com>

Oh, crap: actually this warning has just been fixed by Sudip Mukherjee
and is already queued by David here:
https://patchwork.ozlabs.org/patch/572610/

So, sorry, I've shot too fast: NACK...

Bye,

>> ---
>>  drivers/net/ethernet/cadence/macb.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c
>> index 9d9984a87d42..d3aa74f9db79 100644
>> --- a/drivers/net/ethernet/cadence/macb.c
>> +++ b/drivers/net/ethernet/cadence/macb.c
>> @@ -2268,6 +2268,7 @@ static int macb_clk_init(struct platform_device *pdev, struct clk **pclk,
>>  {
>>  	int err;
>>  
>> +	*tx_clk = *hclk = NULL;
>>  	*pclk = devm_clk_get(&pdev->dev, "pclk");
>>  	if (IS_ERR(*pclk)) {
>>  		err = PTR_ERR(*pclk);
>>
> 
> 


-- 
Nicolas Ferre