* [PATCH] counter: Set counter device name
@ 2022-02-03 7:34 William Breathitt Gray
2022-02-03 9:00 ` Uwe Kleine-König
0 siblings, 1 reply; 4+ messages in thread
From: William Breathitt Gray @ 2022-02-03 7:34 UTC (permalink / raw)
To: jic23; +Cc: u.kleine-koenig, linux-iio, linux-kernel, William Breathitt Gray
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:
+
ida_free(&counter_ida, dev->id);
err_ida_alloc:
@@ -250,7 +259,8 @@ static int __init counter_init(void)
if (err < 0)
return err;
- err = alloc_chrdev_region(&counter_devt, 0, COUNTER_DEV_MAX, "counter");
+ err = alloc_chrdev_region(&counter_devt, 0, COUNTER_DEV_MAX,
+ COUNTER_NAME);
if (err < 0)
goto err_unregister_bus;
base-commit: 7b9c8e1a0ca18a62565ee0e28b23baf7b176e96f
--
2.35.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] counter: Set counter device name
2022-02-03 7:34 [PATCH] counter: Set counter device name William Breathitt Gray
@ 2022-02-03 9:00 ` Uwe Kleine-König
2022-02-04 6:41 ` William Breathitt Gray
0 siblings, 1 reply; 4+ messages in thread
From: Uwe Kleine-König @ 2022-02-03 9:00 UTC (permalink / raw)
To: William Breathitt Gray; +Cc: jic23, linux-iio, linux-kernel
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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
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] counter: Set counter device name
2022-02-03 9:00 ` Uwe Kleine-König
@ 2022-02-04 6:41 ` William Breathitt Gray
2022-02-04 7:43 ` Uwe Kleine-König
0 siblings, 1 reply; 4+ messages in thread
From: William Breathitt Gray @ 2022-02-04 6:41 UTC (permalink / raw)
To: Uwe Kleine-König; +Cc: jic23, linux-iio, linux-kernel
[-- Attachment #1: Type: text/plain, Size: 2169 bytes --]
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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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] counter: Set counter device name
2022-02-04 6:41 ` William Breathitt Gray
@ 2022-02-04 7:43 ` Uwe Kleine-König
0 siblings, 0 replies; 4+ messages in thread
From: Uwe Kleine-König @ 2022-02-04 7:43 UTC (permalink / raw)
To: William Breathitt Gray; +Cc: jic23, linux-iio, linux-kernel
[-- Attachment #1: Type: text/plain, Size: 2552 bytes --]
On Fri, Feb 04, 2022 at 03:41:33PM +0900, William Breathitt Gray wrote:
> 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.
>
> 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.
Ah I see. Still I would consider it a layer violation to have to know
this has to be freed (also about kfree vs. kfree_const). I suggest to
move setting the name after the call to device_initialize(). Then the
device core cares for that.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
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2022-02-03 7:34 [PATCH] counter: Set counter device name William Breathitt Gray
2022-02-03 9:00 ` Uwe Kleine-König
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2022-02-04 7:43 ` Uwe Kleine-König
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