Messages in this thread | | | Subject | Re: [PATCH v2 04/23] counter: Provide a wrapper to access device private data | From | Lars-Peter Clausen <> | Date | Mon, 27 Dec 2021 13:28:42 +0100 |
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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
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