| Message ID | 20211227094526.698714-5-u.kleine-koenig@pengutronix.de (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | [v2,01/23] counter: Use container_of instead of drvdata to track counter_device | expand |
On Mon, Dec 27, 2021 at 10:45:07AM +0100, Uwe Kleine-König wrote: > For now this just wraps accessing struct counter_device::priv. However > this is about to change and converting drivers to this helper > individually makes fixing device lifetime issues result in easier to > review patches. > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> > --- > drivers/counter/counter-core.c | 12 ++++++++++++ > include/linux/counter.h | 2 ++ > 2 files changed, 14 insertions(+) > > diff --git a/drivers/counter/counter-core.c b/drivers/counter/counter-core.c > index f053a43c6c04..00c41f28c101 100644 > --- a/drivers/counter/counter-core.c > +++ b/drivers/counter/counter-core.c > @@ -45,6 +45,18 @@ static struct bus_type counter_bus_type = { > > static dev_t counter_devt; > > +/** > + * counter_priv - access counter device private data > + * @counter: counter device > + * > + * Get the counter device private data > + */ > +void *counter_priv(const struct counter_device *const counter) > +{ > + return counter->priv; > +} > +EXPORT_SYMBOL_GPL(counter_priv); Shouldn't this be usin gdev_get_drvdata() and using the private data pointer that is already on the struct device structure itself? The void *priv; should be dropped from struct counter_device entirely. Oh ick, I just now looked at 'struct counter_device', there are other reference counting issues in there (hint, struct cdev has a reference count...) But that's independent of this patch series... thanks, greg k-h
On 12/27/21 12:02 PM, Greg Kroah-Hartman wrote: > On Mon, Dec 27, 2021 at 10:45:07AM +0100, Uwe Kleine-König wrote: >> For now this just wraps accessing struct counter_device::priv. However >> this is about to change and converting drivers to this helper >> individually makes fixing device lifetime issues result in easier to >> review patches. >> >> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> >> --- >> drivers/counter/counter-core.c | 12 ++++++++++++ >> include/linux/counter.h | 2 ++ >> 2 files changed, 14 insertions(+) >> >> diff --git a/drivers/counter/counter-core.c b/drivers/counter/counter-core.c >> index f053a43c6c04..00c41f28c101 100644 >> --- a/drivers/counter/counter-core.c >> +++ b/drivers/counter/counter-core.c >> @@ -45,6 +45,18 @@ static struct bus_type counter_bus_type = { >> >> static dev_t counter_devt; >> >> +/** >> + * counter_priv - access counter device private data >> + * @counter: counter device >> + * >> + * Get the counter device private data >> + */ >> +void *counter_priv(const struct counter_device *const counter) >> +{ >> + return counter->priv; >> +} >> +EXPORT_SYMBOL_GPL(counter_priv); > Shouldn't this be usin gdev_get_drvdata() and using the private data > pointer that is already on the struct device structure itself? The void > *priv; should be dropped from struct counter_device entirely. > > Oh ick, I just now looked at 'struct counter_device', there are other > reference counting issues in there (hint, struct cdev has a reference > count...) But that's independent of this patch series... This is not a problem. The struct cdev holds a reference to the struct dev. This allows them to use the same allocation. As long as there is a reference to the cdev there will be a reference to the dev and the memory will be kept alive.
On Mon, Dec 27, 2021 at 12:34:28PM +0100, Lars-Peter Clausen wrote: > On 12/27/21 12:02 PM, Greg Kroah-Hartman wrote: > > On Mon, Dec 27, 2021 at 10:45:07AM +0100, Uwe Kleine-König wrote: > > > For now this just wraps accessing struct counter_device::priv. However > > > this is about to change and converting drivers to this helper > > > individually makes fixing device lifetime issues result in easier to > > > review patches. > > > > > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> > > > --- > > > drivers/counter/counter-core.c | 12 ++++++++++++ > > > include/linux/counter.h | 2 ++ > > > 2 files changed, 14 insertions(+) > > > > > > diff --git a/drivers/counter/counter-core.c b/drivers/counter/counter-core.c > > > index f053a43c6c04..00c41f28c101 100644 > > > --- a/drivers/counter/counter-core.c > > > +++ b/drivers/counter/counter-core.c > > > @@ -45,6 +45,18 @@ static struct bus_type counter_bus_type = { > > > static dev_t counter_devt; > > > +/** > > > + * counter_priv - access counter device private data > > > + * @counter: counter device > > > + * > > > + * Get the counter device private data > > > + */ > > > +void *counter_priv(const struct counter_device *const counter) > > > +{ > > > + return counter->priv; > > > +} > > > +EXPORT_SYMBOL_GPL(counter_priv); > > Shouldn't this be usin gdev_get_drvdata() and using the private data > > pointer that is already on the struct device structure itself? The void > > *priv; should be dropped from struct counter_device entirely. > > > > Oh ick, I just now looked at 'struct counter_device', there are other > > reference counting issues in there (hint, struct cdev has a reference > > count...) But that's independent of this patch series... > This is not a problem. The struct cdev holds a reference to the struct dev. > This allows them to use the same allocation. As long as there is a reference > to the cdev there will be a reference to the dev and the memory will be kept > alive. Ick, a cdev shouldn't be doing stuff like that, but I see how people like to use it that way :( Ok, it's fine for now, but yet-another-reaason why the cdev api is a mess in places... thanks, greg k-h
On 12/27/21 12:52 PM, Greg Kroah-Hartman wrote: > On Mon, Dec 27, 2021 at 12:34:28PM +0100, Lars-Peter Clausen wrote: >> On 12/27/21 12:02 PM, Greg Kroah-Hartman wrote: >>> On Mon, Dec 27, 2021 at 10:45:07AM +0100, Uwe Kleine-König wrote: >>>> For now this just wraps accessing struct counter_device::priv. However >>>> this is about to change and converting drivers to this helper >>>> individually makes fixing device lifetime issues result in easier to >>>> review patches. >>>> >>>> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> >>>> --- >>>> drivers/counter/counter-core.c | 12 ++++++++++++ >>>> include/linux/counter.h | 2 ++ >>>> 2 files changed, 14 insertions(+) >>>> >>>> diff --git a/drivers/counter/counter-core.c b/drivers/counter/counter-core.c >>>> index f053a43c6c04..00c41f28c101 100644 >>>> --- a/drivers/counter/counter-core.c >>>> +++ b/drivers/counter/counter-core.c >>>> @@ -45,6 +45,18 @@ static struct bus_type counter_bus_type = { >>>> static dev_t counter_devt; >>>> +/** >>>> + * counter_priv - access counter device private data >>>> + * @counter: counter device >>>> + * >>>> + * Get the counter device private data >>>> + */ >>>> +void *counter_priv(const struct counter_device *const counter) >>>> +{ >>>> + return counter->priv; >>>> +} >>>> +EXPORT_SYMBOL_GPL(counter_priv); >>> Shouldn't this be usin gdev_get_drvdata() and using the private data >>> pointer that is already on the struct device structure itself? The void >>> *priv; should be dropped from struct counter_device entirely. >>> >>> Oh ick, I just now looked at 'struct counter_device', there are other >>> reference counting issues in there (hint, struct cdev has a reference >>> count...) But that's independent of this patch series... >> This is not a problem. The struct cdev holds a reference to the struct dev. >> This allows them to use the same allocation. As long as there is a reference >> to the cdev there will be a reference to the dev and the memory will be kept >> alive. > Ick, a cdev shouldn't be doing stuff like that, but I see how people > like to use it that way :( > Can you explain why cdev shouldn't be doing that? This commit has some backstory why this is done https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=233ed09d7fdacf592ee91e6c97ce5f4364fbe7c0
On Mon, 27 Dec 2021 10:45:07 +0100 Uwe Kleine-König <u.kleine-koenig@pengutronix.de> wrote: > For now this just wraps accessing struct counter_device::priv. However > this is about to change and converting drivers to this helper > individually makes fixing device lifetime issues result in easier to > review patches. > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > --- > drivers/counter/counter-core.c | 12 ++++++++++++ > include/linux/counter.h | 2 ++ > 2 files changed, 14 insertions(+) > > diff --git a/drivers/counter/counter-core.c b/drivers/counter/counter-core.c > index f053a43c6c04..00c41f28c101 100644 > --- a/drivers/counter/counter-core.c > +++ b/drivers/counter/counter-core.c > @@ -45,6 +45,18 @@ static struct bus_type counter_bus_type = { > > static dev_t counter_devt; > > +/** > + * counter_priv - access counter device private data > + * @counter: counter device > + * > + * Get the counter device private data > + */ > +void *counter_priv(const struct counter_device *const counter) > +{ > + return counter->priv; > +} > +EXPORT_SYMBOL_GPL(counter_priv); > + > /** > * counter_register - register Counter to the system > * @counter: pointer to Counter to register > diff --git a/include/linux/counter.h b/include/linux/counter.h > index b7d0a00a61cf..8daaa38c71d8 100644 > --- a/include/linux/counter.h > +++ b/include/linux/counter.h > @@ -329,6 +329,8 @@ struct counter_device { > struct mutex ops_exist_lock; > }; > > +void *counter_priv(const struct counter_device *const counter); > + > int counter_register(struct counter_device *const counter); > void counter_unregister(struct counter_device *const counter); > int devm_counter_register(struct device *dev,
On Mon, Dec 27, 2021 at 10:45:07AM +0100, Uwe Kleine-König wrote: > For now this just wraps accessing struct counter_device::priv. However > this is about to change and converting drivers to this helper > individually makes fixing device lifetime issues result in easier to > review patches. > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com> > --- > drivers/counter/counter-core.c | 12 ++++++++++++ > include/linux/counter.h | 2 ++ > 2 files changed, 14 insertions(+) > > diff --git a/drivers/counter/counter-core.c b/drivers/counter/counter-core.c > index f053a43c6c04..00c41f28c101 100644 > --- a/drivers/counter/counter-core.c > +++ b/drivers/counter/counter-core.c > @@ -45,6 +45,18 @@ static struct bus_type counter_bus_type = { > > static dev_t counter_devt; > > +/** > + * counter_priv - access counter device private data > + * @counter: counter device > + * > + * Get the counter device private data > + */ > +void *counter_priv(const struct counter_device *const counter) > +{ > + return counter->priv; > +} > +EXPORT_SYMBOL_GPL(counter_priv); > + > /** > * counter_register - register Counter to the system > * @counter: pointer to Counter to register > diff --git a/include/linux/counter.h b/include/linux/counter.h > index b7d0a00a61cf..8daaa38c71d8 100644 > --- a/include/linux/counter.h > +++ b/include/linux/counter.h > @@ -329,6 +329,8 @@ struct counter_device { > struct mutex ops_exist_lock; > }; > > +void *counter_priv(const struct counter_device *const counter); > + > int counter_register(struct counter_device *const counter); > void counter_unregister(struct counter_device *const counter); > int devm_counter_register(struct device *dev, > -- > 2.33.0 >
diff --git a/drivers/counter/counter-core.c b/drivers/counter/counter-core.c index f053a43c6c04..00c41f28c101 100644 --- a/drivers/counter/counter-core.c +++ b/drivers/counter/counter-core.c @@ -45,6 +45,18 @@ static struct bus_type counter_bus_type = { static dev_t counter_devt; +/** + * counter_priv - access counter device private data + * @counter: counter device + * + * Get the counter device private data + */ +void *counter_priv(const struct counter_device *const counter) +{ + return counter->priv; +} +EXPORT_SYMBOL_GPL(counter_priv); + /** * counter_register - register Counter to the system * @counter: pointer to Counter to register diff --git a/include/linux/counter.h b/include/linux/counter.h index b7d0a00a61cf..8daaa38c71d8 100644 --- a/include/linux/counter.h +++ b/include/linux/counter.h @@ -329,6 +329,8 @@ struct counter_device { struct mutex ops_exist_lock; }; +void *counter_priv(const struct counter_device *const counter); + int counter_register(struct counter_device *const counter); void counter_unregister(struct counter_device *const counter); int devm_counter_register(struct device *dev,
For now this just wraps accessing struct counter_device::priv. However this is about to change and converting drivers to this helper individually makes fixing device lifetime issues result in easier to review patches. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> --- drivers/counter/counter-core.c | 12 ++++++++++++ include/linux/counter.h | 2 ++ 2 files changed, 14 insertions(+)