Re: [PATCH] Input: pxrc - simplify mutex handling with guard macro

Johan Hovold
2023-12-01T13:28:51Z

On Fri, Dec 01, 2023 at 01:08:45PM +0100, Marcus Folkesson wrote:
> Use the guard(mutex) macro for handle mutex lock/unlocks.
>
> Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>

A couple of drive-by comments below.

> ---
> drivers/input/joystick/pxrc.c | 27 +++++++++++----------------
> 1 file changed, 11 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/input/joystick/pxrc.c b/drivers/input/joystick/pxrc.c
> index ea2bf5951d67..3c3bf7179b46 100644
> --- a/drivers/input/joystick/pxrc.c
> +++ b/drivers/input/joystick/pxrc.c
> @@ -5,15 +5,17 @@
> * Copyright (C) 2018 Marcus Folkesson <marcus.folkesson@gmail.com>
> */
>
> -#include <linux/kernel.h>
> +#include <linux/cleanup.h>
> #include <linux/errno.h>
> -#include <linux/slab.h>
> +#include <linux/input.h>
> +#include <linux/kernel.h>
> #include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/slab.h>
> #include <linux/uaccess.h>
> +
> #include <linux/usb.h>
> #include <linux/usb/input.h>
> -#include <linux/mutex.h>
> -#include <linux/input.h>

Looks like an unrelated change.

> #define PXRC_VENDOR_ID 0x1781
> #define PXRC_PRODUCT_ID 0x0898
> @@ -89,25 +91,20 @@ static int pxrc_open(struct input_dev *input)
> dev_err(&pxrc->intf->dev,
> "%s - usb_submit_urb failed, error: %d\n",
> __func__, retval);
> - retval = -EIO;
> - goto out;
> + return -EIO;
> }
>
> pxrc->is_open = true;
> -
> -out:
> - mutex_unlock(&pxrc->pm_mutex);
> - return retval;
> + return 0;
> }

Eh, this looks obviously broken. Did you not test this before
submitting? I assume lockdep would complain loudly too.

You're apparently the author of this driver and can test it, but I fear
the coming onslaught of untested guard conversions from the "cleanup"
crew. Not sure I find the result generally more readable either.

Johan