device_register() calls device_initialize(),
according to doc of device_initialize:
Use put_device() to give up your reference instead of freeing
* @dev directly once you have called this function.
To prevent potential memleak, use put_device() instead call kfree
directly.
Signed-off-by: Miaoqian Lin <[email protected]>
---
drivers/hwtracing/coresight/coresight-syscfg.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c
index 43054568430f..007fa1c761a7 100644
--- a/drivers/hwtracing/coresight/coresight-syscfg.c
+++ b/drivers/hwtracing/coresight/coresight-syscfg.c
@@ -764,7 +764,7 @@ struct device *cscfg_device(void)
/* Must have a release function or the kernel will complain on module unload */
static void cscfg_dev_release(struct device *dev)
{
- kfree(cscfg_mgr);
+ put_device(dev);
cscfg_mgr = NULL;
}
--
2.17.1
Good morning,
On Mon, Jan 10, 2022 at 07:31:00AM +0000, Miaoqian Lin wrote:
> device_register() calls device_initialize(),
> according to doc of device_initialize:
>
> Use put_device() to give up your reference instead of freeing
> * @dev directly once you have called this function.
That is _if_ device_initialize() is called manually. In this instance
@dev is registered with device_register() and unregistered with
device_unregister(). The latter conforms to the comment you pointed out and
calls put_device() as expected.
Thanks,
Mathieu
>
> To prevent potential memleak, use put_device() instead call kfree
> directly.
>
> Signed-off-by: Miaoqian Lin <[email protected]>
> ---
> drivers/hwtracing/coresight/coresight-syscfg.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c
> index 43054568430f..007fa1c761a7 100644
> --- a/drivers/hwtracing/coresight/coresight-syscfg.c
> +++ b/drivers/hwtracing/coresight/coresight-syscfg.c
> @@ -764,7 +764,7 @@ struct device *cscfg_device(void)
> /* Must have a release function or the kernel will complain on module unload */
> static void cscfg_dev_release(struct device *dev)
> {
> - kfree(cscfg_mgr);
> + put_device(dev);
> cscfg_mgr = NULL;
> }
>
> --
> 2.17.1
>
On Thu, Jan 20, 2022 at 10:56:42AM -0700, Mathieu Poirier wrote:
> Good morning,
>
> On Mon, Jan 10, 2022 at 07:31:00AM +0000, Miaoqian Lin wrote:
> > device_register() calls device_initialize(),
> > according to doc of device_initialize:
> >
> > Use put_device() to give up your reference instead of freeing
> > * @dev directly once you have called this function.
>
> That is _if_ device_initialize() is called manually. In this instance
> @dev is registered with device_register() and unregistered with
> device_unregister(). The latter conforms to the comment you pointed out and
> calls put_device() as expected.
I originally misunderstood the context - you are referring to the failure path in
cscfg_create_device(). You are correct about needing to call put_device() but
your solution will not work when the module is unloaded properly and
device_unregister() is called by way of cscfg_clear_device(). In that case
device_unregister() is already calling put_device().
Here simply calling put_device() instead of cscfg_dev_release() in the error
path should do just fine. That will call cscfg_dev_release() and the memory
allocated for cscfg_mgr will be release.
>
> Thanks,
> Mathieu
>
> >
> > To prevent potential memleak, use put_device() instead call kfree
> > directly.
> >
> > Signed-off-by: Miaoqian Lin <[email protected]>
> > ---
> > drivers/hwtracing/coresight/coresight-syscfg.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c
> > index 43054568430f..007fa1c761a7 100644
> > --- a/drivers/hwtracing/coresight/coresight-syscfg.c
> > +++ b/drivers/hwtracing/coresight/coresight-syscfg.c
> > @@ -764,7 +764,7 @@ struct device *cscfg_device(void)
> > /* Must have a release function or the kernel will complain on module unload */
> > static void cscfg_dev_release(struct device *dev)
> > {
> > - kfree(cscfg_mgr);
> > + put_device(dev);
> > cscfg_mgr = NULL;
> > }
> >
> > --
> > 2.17.1
> >
device_register() calls device_initialize(),
according to doc of device_initialize:
Use put_device() to give up your reference instead of freeing
* @dev directly once you have called this function.
To prevent potential memleak, use put_device() for error handling.
Signed-off-by: Miaoqian Lin <[email protected]>
---
Changes in v2:
- simply call put_device() instead of cscfg_dev_release() in the error
path of cscfg_create_device.
---
drivers/hwtracing/coresight/coresight-syscfg.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c
index 43054568430f..c30989e0675f 100644
--- a/drivers/hwtracing/coresight/coresight-syscfg.c
+++ b/drivers/hwtracing/coresight/coresight-syscfg.c
@@ -791,7 +791,7 @@ static int cscfg_create_device(void)
err = device_register(dev);
if (err)
- cscfg_dev_release(dev);
+ put_device(dev);
create_dev_exit_unlock:
mutex_unlock(&cscfg_mutex);
--
2.17.1
On Mon, Jan 24, 2022 at 12:41:21PM +0000, Miaoqian Lin wrote:
> device_register() calls device_initialize(),
> according to doc of device_initialize:
>
> Use put_device() to give up your reference instead of freeing
> * @dev directly once you have called this function.
>
> To prevent potential memleak, use put_device() for error handling.
>
> Signed-off-by: Miaoqian Lin <[email protected]>
> ---
> Changes in v2:
> - simply call put_device() instead of cscfg_dev_release() in the error
> path of cscfg_create_device.
> ---
> drivers/hwtracing/coresight/coresight-syscfg.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c
> index 43054568430f..c30989e0675f 100644
> --- a/drivers/hwtracing/coresight/coresight-syscfg.c
> +++ b/drivers/hwtracing/coresight/coresight-syscfg.c
> @@ -791,7 +791,7 @@ static int cscfg_create_device(void)
>
> err = device_register(dev);
> if (err)
> - cscfg_dev_release(dev);
> + put_device(dev);
Applied.
Thanks,
Mathieu
>
> create_dev_exit_unlock:
> mutex_unlock(&cscfg_mutex);
> --
> 2.17.1
>