[PATCH] mux: core: Replace manual put_device() with __free(put_device)

[PATCH] mux: core: Replace manual put_device() with __free(put_device)

[Maxwell Doose]

The current code for returning on failure in mux_get() uses manual
put_device() calls. Refactor and replace them with a new variable for
the pointer to the underlying device and __free(put_device).

Signed-off-by: Maxwell Doose <m32285159@gmail.com>
---
 drivers/mux/core.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/mux/core.c b/drivers/mux/core.c
index 23538de2c91b..a31e06388588 100644
--- a/drivers/mux/core.c
+++ b/drivers/mux/core.c
@@ -586,13 +586,13 @@ static struct mux_control *mux_get(struct device *dev, const char *mux_name,
 	if (!mux_chip)
 		return ERR_PTR(-EPROBE_DEFER);
 
+	struct device *mux_dev __free(put_device) = &mux_chip->dev;
 	controller = 0;
 	if (state) {
 		if (args.args_count > 2 || args.args_count == 0 ||
 		    (args.args_count < 2 && mux_chip->controllers > 1)) {
 			dev_err(dev, "%pOF: wrong #mux-state-cells for %pOF\n",
 				np, args.np);
-			put_device(&mux_chip->dev);
 			return ERR_PTR(-EINVAL);
 		}
 
@@ -608,7 +608,6 @@ static struct mux_control *mux_get(struct device *dev, const char *mux_name,
 		    (!args.args_count && mux_chip->controllers > 1)) {
 			dev_err(dev, "%pOF: wrong #mux-control-cells for %pOF\n",
 				np, args.np);
-			put_device(&mux_chip->dev);
 			return ERR_PTR(-EINVAL);
 		}
 
@@ -619,7 +618,6 @@ static struct mux_control *mux_get(struct device *dev, const char *mux_name,
 	if (controller >= mux_chip->controllers) {
 		dev_err(dev, "%pOF: bad mux controller %u specified in %pOF\n",
 			np, controller, args.np);
-		put_device(&mux_chip->dev);
 		return ERR_PTR(-EINVAL);
 	}
 
-- 
2.54.0

Re: [PATCH] mux: core: Replace manual put_device() with __free(put_device)

[Peter Rosin]

Hi!

On 2026-06-02 06:36, Maxwell Doose wrote:
> The current code for returning on failure in mux_get() uses manual
> put_device() calls. Refactor and replace them with a new variable for
> the pointer to the underlying device and __free(put_device).
> 
> Signed-off-by: Maxwell Doose <m32285159@gmail.com>
> ---
>   drivers/mux/core.c | 4 +---
>   1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/mux/core.c b/drivers/mux/core.c
> index 23538de2c91b..a31e06388588 100644
> --- a/drivers/mux/core.c
> +++ b/drivers/mux/core.c
> @@ -586,13 +586,13 @@ static struct mux_control *mux_get(struct device *dev, const char *mux_name,
>   	if (!mux_chip)
>   		return ERR_PTR(-EPROBE_DEFER);
>   
> +	struct device *mux_dev __free(put_device) = &mux_chip->dev;

This will also run put_device() on success, which IIUC is broken.
I'm not sure it makes sense to use __free() when the exit behavior
is conditional like this?

Cheers,
Peter

>   	controller = 0;
>   	if (state) {
>   		if (args.args_count > 2 || args.args_count == 0 ||
>   		    (args.args_count < 2 && mux_chip->controllers > 1)) {
>   			dev_err(dev, "%pOF: wrong #mux-state-cells for %pOF\n",
>   				np, args.np);
> -			put_device(&mux_chip->dev);
>   			return ERR_PTR(-EINVAL);
>   		}
>   
> @@ -608,7 +608,6 @@ static struct mux_control *mux_get(struct device *dev, const char *mux_name,
>   		    (!args.args_count && mux_chip->controllers > 1)) {
>   			dev_err(dev, "%pOF: wrong #mux-control-cells for %pOF\n",
>   				np, args.np);
> -			put_device(&mux_chip->dev);
>   			return ERR_PTR(-EINVAL);
>   		}
>   
> @@ -619,7 +618,6 @@ static struct mux_control *mux_get(struct device *dev, const char *mux_name,
>   	if (controller >= mux_chip->controllers) {
>   		dev_err(dev, "%pOF: bad mux controller %u specified in %pOF\n",
>   			np, controller, args.np);
> -		put_device(&mux_chip->dev);
>   		return ERR_PTR(-EINVAL);
>   	}
>   

Re: [PATCH] mux: core: Replace manual put_device() with __free(put_device)

[Maxwell Doose]

On Tue, 2 Jun 2026 11:03:45 +0200
Peter Rosin <peda@lysator.liu.se> wrote:

> Hi!
> 
> On 2026-06-02 06:36, Maxwell Doose wrote:
> > The current code for returning on failure in mux_get() uses manual
> > put_device() calls. Refactor and replace them with a new variable for
> > the pointer to the underlying device and __free(put_device).
> > 
> > Signed-off-by: Maxwell Doose <m32285159@gmail.com>
> > ---
> >   drivers/mux/core.c | 4 +---
> >   1 file changed, 1 insertion(+), 3 deletions(-)
> > 
> > diff --git a/drivers/mux/core.c b/drivers/mux/core.c
> > index 23538de2c91b..a31e06388588 100644
> > --- a/drivers/mux/core.c
> > +++ b/drivers/mux/core.c
> > @@ -586,13 +586,13 @@ static struct mux_control *mux_get(struct device *dev, const char *mux_name,
> >   	if (!mux_chip)
> >   		return ERR_PTR(-EPROBE_DEFER);
> >   
> > +	struct device *mux_dev __free(put_device) = &mux_chip->dev;  
> 
> This will also run put_device() on success, which IIUC is broken.

Shoot, I must've missed the no_free_ptr() at the end. Nice catch.

> I'm not sure it makes sense to use __free() when the exit behavior
> is conditional like this?

I guess once we do no_free_ptr() then it should be fine, since
that should prevent the put_device() from firing on the happy path.

-- 
best regards,
max

ps:
I hope I'm not wasting your time, I was just looking at random
subsystems and I thought mux would be rather interesting given how
small it is (I do stuff in iio, and the contrast is crazy to me!)
Regarding why I sent this patch, it's mostly because this subsystem
interested me but I quite literally couldn't find anything to fix
(except one single const-correctness issue that checkpatch pointed
out)!