linux-kernel - Re: [PATCH] stm class: fix device leak in open error path

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Message-ID: <20161118130115.GG10490@localhost>
Date:   Fri, 18 Nov 2016 14:01:15 +0100
From:   Johan Hovold <johan@...nel.org>
To:     Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc:     Johan Hovold <johan@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] stm class: fix device leak in open error path

On Fri, Nov 18, 2016 at 01:55:58PM +0200, Alexander Shishkin wrote:
> Johan Hovold <johan@...nel.org> writes:
> 
> > Make sure to drop the reference taken by class_find_device() also on
> > allocation errors in open().
> >
> > Fixes: 7bd1d4093c2f ("stm class: Introduce an abstraction for...")
> > Signed-off-by: Johan Hovold <johan@...nel.org>
> 
> Good catch, thanks! I'm going to change it a bit to look like this
> if you don't mind:
> 
> diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
> index 51f81d64ca..cf6c9ea14c 100644
> --- a/drivers/hwtracing/stm/core.c
> +++ b/drivers/hwtracing/stm/core.c
> @@ -361,7 +361,7 @@ static int stm_char_open(struct inode *inode, struct file *file)
>         struct stm_file *stmf;
>         struct device *dev;
>         unsigned int major = imajor(inode);
> -       int err = -ENODEV;
> +       int err = -ENOMEM;
> 
>         dev = class_find_device(&stm_class, NULL, &major, major_match);
>         if (!dev)
> @@ -369,8 +369,9 @@ static int stm_char_open(struct inode *inode, struct file *file)
> 
>         stmf = kzalloc(sizeof(*stmf), GFP_KERNEL);
>         if (!stmf)
> -               return -ENOMEM;
> +               goto err_put_device;
> 
> +       err = -ENODEV;
>         stm_output_init(&stmf->output);
>         stmf->stm = to_stm_device(dev);

Sure. I find it more readable to set the errno in the error path, but I
don't mind.

Thanks,
Johan