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SubjectRe: [PATCH] counter: Set counter device name
On Thu, Feb 03, 2022 at 10:00:53AM +0100, Uwe Kleine-König wrote:
> On Thu, Feb 03, 2022 at 04:34:59PM +0900, William Breathitt Gray wrote:
> > Naming the counter device provides a convenient way to identify it in
> > devres_log events and similar situations. This patch names the counter
> > device by combining the prefix "counter" with the counter device's
> > unique ID.
> >
> > Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> > Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
> > ---
> > drivers/counter/counter-core.c | 12 +++++++++++-
> > 1 file changed, 11 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/counter/counter-core.c b/drivers/counter/counter-core.c
> > index 7e0957eea094..2ebd9adf0bd2 100644
> > --- a/drivers/counter/counter-core.c
> > +++ b/drivers/counter/counter-core.c
> > @@ -22,6 +22,8 @@
> > #include "counter-chrdev.h"
> > #include "counter-sysfs.h"
> >
> > +#define COUNTER_NAME "counter"
> > +
> > /* Provides a unique ID for each counter device */
> > static DEFINE_IDA(counter_ida);
> >
> > @@ -104,6 +106,10 @@ struct counter_device *counter_alloc(size_t sizeof_priv)
> > goto err_ida_alloc;
> > dev->id = err;
> >
> > + err = dev_set_name(dev, COUNTER_NAME "%d", dev->id);
> > + if (err)
> > + goto err_dev_set_name;
> > +
> > mutex_init(&counter->ops_exist_lock);
> > dev->type = &counter_device_type;
> > dev->bus = &counter_bus_type;
> > @@ -119,6 +125,9 @@ struct counter_device *counter_alloc(size_t sizeof_priv)
> >
> > err_chrdev_add:
> >
> > + kfree(dev_name(dev));
> > +err_dev_set_name:
> > +
>
> I think this is wrong as kobject_cleanup frees the name.
>
> Best regards
> Uwe

This is true once the device is initialized by device_initialize() but
that won't happen until after counter_chrdev_add() is called; if
counter_chrdev_add() fails, we need to free this memory lest it leak
when we return the error code.

I did notice kobject_cleanup() calls kfree_const() on the name rather
than kfree(). Would it make sense to change this patch to call
kfree_const() instead?

William Breathitt Gray
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