linux-kernel - Re: [PATCH] mtd: rawnand: jz4780: fix object reference leaks in jz4780_bch

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Message-ID: <20190205143023.307207b6@xps13>
Date:   Tue, 5 Feb 2019 14:30:23 +0100
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     wen yang <yellowriver2010@...mail.com>
Cc:     "harveyhuntnexus@...il.com" <harveyhuntnexus@...il.com>,
        "bbrezillon@...nel.org" <bbrezillon@...nel.org>,
        "richard@....at" <richard@....at>,
        "dwmw2@...radead.org" <dwmw2@...radead.org>,
        "computersforpeace@...il.com" <computersforpeace@...il.com>,
        "marek.vasut@...il.com" <marek.vasut@...il.com>,
        "nicolas.ferre@...rochip.com" <nicolas.ferre@...rochip.com>,
        "alexandre.belloni@...tlin.com" <alexandre.belloni@...tlin.com>,
        "ludovic.desroches@...rochip.com" <ludovic.desroches@...rochip.com>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mtd: rawnand: jz4780: fix object reference leaks in
 jz4780_bch_get

Hi wen,

wen yang <yellowriver2010@...mail.com> wrote on Tue, 5 Feb 2019
09:36:48 +0000:

> of_find_device_by_node() takes a reference to the struct device
> when it finds a match via get_device, there is no need to call
> get_device() twice.
> We also should make sure to drop the reference to the device
> taken by of_find_device_by_node() on driver unbind.
> 
> Fixes: ae02ab00aa3c ("mtd: nand: jz4780: driver for NAND devices on JZ4780 SoCs")
> Signed-off-by: Wen Yang <yellowriver2010@...mail.com>
> Suggested-by: Boris Brezillon <bbrezillon@...nel.org>
> Cc: Harvey Hunt <harveyhuntnexus@...il.com>
> Cc: Boris Brezillon <bbrezillon@...nel.org>
> Cc: Miquel Raynal <miquel.raynal@...tlin.com>
> Cc: Richard Weinberger <richard@....at>
> Cc: David Woodhouse <dwmw2@...radead.org>
> Cc: Brian Norris <computersforpeace@...il.com>
> Cc: Marek Vasut <marek.vasut@...il.com>
> Cc: linux-mtd@...ts.infradead.org
> Cc: linux-kernel@...r.kernel.org
> ---
>  drivers/mtd/nand/raw/jz4780_bch.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/jz4780_bch.c b/drivers/mtd/nand/raw/jz4780_bch.c
> index 7201827..d0ce5de 100644
> --- a/drivers/mtd/nand/raw/jz4780_bch.c
> +++ b/drivers/mtd/nand/raw/jz4780_bch.c
> @@ -279,17 +279,24 @@ static struct jz4780_bch *jz4780_bch_get(struct device_node *np)
>  {
>  	struct platform_device *pdev;
>  	struct jz4780_bch *bch;
> +	int ret;
>  
>  	pdev = of_find_device_by_node(np);
> -	if (!pdev || !platform_get_drvdata(pdev))
> +	if (!pdev)
>  		return ERR_PTR(-EPROBE_DEFER);
> -
> -	get_device(&pdev->dev);
> +	if (!platform_get_drvdata(pdev)) {
> +		ret = -EPROBE_DEFER;
> +		goto err_put_device;
> +	}
>  
>  	bch = platform_get_drvdata(pdev);
>  	clk_prepare_enable(bch->clk);
>  
>  	return bch;
> +
> +err_put_device:
> +	put_device(&pdev->dev);
> +	return ERR_PTR(ret);

While there is only one user of this label, I think we don't want it.

Thanks,
Miquèl