Re: [RFC PATCH] usb: core: correct usb_get_dev() documentation
On Thu, Oct 27, 2016 at 04:49:18PM -0700, Dmitry Torokhov wrote: > On Thu, Oct 27, 2016 at 03:02:30PM -0700, Brian Norris wrote: > > In reading through a USB interface driver, I noticed that it called > > usb_{get,put}_dev() in its probe() and disconnect() methods. This seemed > > unnecessary, but a look at the comments here matched the usage. > > > > USB interface devices seem to be well covered by the parent/child > > relationship of the device model, and so it should be unnecessary for a > > child device to grab a refcount on its parent device. > > > > Signed-off-by: Brian Norris> > Yes, usb_device is parent of usb_interface and device core does "parent > = get_device(dev->parent);" as part of device_add() when registering new > interfaces. > > Reviewed-by: Dmitry Torokhov > Yes, current code seems a little messy for get{put}_device. Eg, for USB device, it tries to call get_device again at usb_set_configuration when create its child device (interface device). For USB interface device, it handles get{put}_device at message.c for common interface, it seems to be not necessary to call usb_get{put}_dev again at individual interface driver. Peter > > --- > > This reflects my understanding (and testing), as well as the majority of > > usage > > -- there are *very* few interface drivers that actually call usb_get_dev(). > > If > > I'm wrong, please feel free to tell me so! But I thought patching the > > documentation would be the best way to solicit a response :) > > > > drivers/usb/core/usb.c | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c > > index 592151461017..0ba7e070f04e 100644 > > --- a/drivers/usb/core/usb.c > > +++ b/drivers/usb/core/usb.c > > @@ -539,9 +539,9 @@ EXPORT_SYMBOL_GPL(usb_alloc_dev); > > * > > * Each live reference to a device should be refcounted. > > * > > - * Drivers for USB interfaces should normally record such references in > > - * their probe() methods, when they bind to an interface, and release > > - * them by calling usb_put_dev(), in their disconnect() methods. > > + * The device driver core automatically handles this refcounting for USB > > + * interface drivers, but this API can be used for non-parent/child > > + * relationships. > > * > > * Return: A pointer to the device with the incremented reference counter. > > */ > > -- > > 2.8.0.rc3.226.g39d4020 > > > > -- > Dmitry > -- > To unsubscribe from this list: send the line "unsubscribe linux-usb" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Best Regards, Peter Chen
Re: [RFC PATCH] usb: core: correct usb_get_dev() documentation
On Thu, Oct 27, 2016 at 04:49:18PM -0700, Dmitry Torokhov wrote: > On Thu, Oct 27, 2016 at 03:02:30PM -0700, Brian Norris wrote: > > In reading through a USB interface driver, I noticed that it called > > usb_{get,put}_dev() in its probe() and disconnect() methods. This seemed > > unnecessary, but a look at the comments here matched the usage. > > > > USB interface devices seem to be well covered by the parent/child > > relationship of the device model, and so it should be unnecessary for a > > child device to grab a refcount on its parent device. > > > > Signed-off-by: Brian Norris > > Yes, usb_device is parent of usb_interface and device core does "parent > = get_device(dev->parent);" as part of device_add() when registering new > interfaces. > > Reviewed-by: Dmitry Torokhov > Yes, current code seems a little messy for get{put}_device. Eg, for USB device, it tries to call get_device again at usb_set_configuration when create its child device (interface device). For USB interface device, it handles get{put}_device at message.c for common interface, it seems to be not necessary to call usb_get{put}_dev again at individual interface driver. Peter > > --- > > This reflects my understanding (and testing), as well as the majority of > > usage > > -- there are *very* few interface drivers that actually call usb_get_dev(). > > If > > I'm wrong, please feel free to tell me so! But I thought patching the > > documentation would be the best way to solicit a response :) > > > > drivers/usb/core/usb.c | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c > > index 592151461017..0ba7e070f04e 100644 > > --- a/drivers/usb/core/usb.c > > +++ b/drivers/usb/core/usb.c > > @@ -539,9 +539,9 @@ EXPORT_SYMBOL_GPL(usb_alloc_dev); > > * > > * Each live reference to a device should be refcounted. > > * > > - * Drivers for USB interfaces should normally record such references in > > - * their probe() methods, when they bind to an interface, and release > > - * them by calling usb_put_dev(), in their disconnect() methods. > > + * The device driver core automatically handles this refcounting for USB > > + * interface drivers, but this API can be used for non-parent/child > > + * relationships. > > * > > * Return: A pointer to the device with the incremented reference counter. > > */ > > -- > > 2.8.0.rc3.226.g39d4020 > > > > -- > Dmitry > -- > To unsubscribe from this list: send the line "unsubscribe linux-usb" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Best Regards, Peter Chen
Re: [RFC PATCH] usb: core: correct usb_get_dev() documentation
On Thu, Oct 27, 2016 at 03:02:30PM -0700, Brian Norris wrote: > In reading through a USB interface driver, I noticed that it called > usb_{get,put}_dev() in its probe() and disconnect() methods. This seemed > unnecessary, but a look at the comments here matched the usage. > > USB interface devices seem to be well covered by the parent/child > relationship of the device model, and so it should be unnecessary for a > child device to grab a refcount on its parent device. > > Signed-off-by: Brian NorrisYes, usb_device is parent of usb_interface and device core does "parent = get_device(dev->parent);" as part of device_add() when registering new interfaces. Reviewed-by: Dmitry Torokhov > --- > This reflects my understanding (and testing), as well as the majority of usage > -- there are *very* few interface drivers that actually call usb_get_dev(). If > I'm wrong, please feel free to tell me so! But I thought patching the > documentation would be the best way to solicit a response :) > > drivers/usb/core/usb.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c > index 592151461017..0ba7e070f04e 100644 > --- a/drivers/usb/core/usb.c > +++ b/drivers/usb/core/usb.c > @@ -539,9 +539,9 @@ EXPORT_SYMBOL_GPL(usb_alloc_dev); > * > * Each live reference to a device should be refcounted. > * > - * Drivers for USB interfaces should normally record such references in > - * their probe() methods, when they bind to an interface, and release > - * them by calling usb_put_dev(), in their disconnect() methods. > + * The device driver core automatically handles this refcounting for USB > + * interface drivers, but this API can be used for non-parent/child > + * relationships. > * > * Return: A pointer to the device with the incremented reference counter. > */ > -- > 2.8.0.rc3.226.g39d4020 > -- Dmitry
Re: [RFC PATCH] usb: core: correct usb_get_dev() documentation
On Thu, Oct 27, 2016 at 03:02:30PM -0700, Brian Norris wrote: > In reading through a USB interface driver, I noticed that it called > usb_{get,put}_dev() in its probe() and disconnect() methods. This seemed > unnecessary, but a look at the comments here matched the usage. > > USB interface devices seem to be well covered by the parent/child > relationship of the device model, and so it should be unnecessary for a > child device to grab a refcount on its parent device. > > Signed-off-by: Brian Norris Yes, usb_device is parent of usb_interface and device core does "parent = get_device(dev->parent);" as part of device_add() when registering new interfaces. Reviewed-by: Dmitry Torokhov > --- > This reflects my understanding (and testing), as well as the majority of usage > -- there are *very* few interface drivers that actually call usb_get_dev(). If > I'm wrong, please feel free to tell me so! But I thought patching the > documentation would be the best way to solicit a response :) > > drivers/usb/core/usb.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c > index 592151461017..0ba7e070f04e 100644 > --- a/drivers/usb/core/usb.c > +++ b/drivers/usb/core/usb.c > @@ -539,9 +539,9 @@ EXPORT_SYMBOL_GPL(usb_alloc_dev); > * > * Each live reference to a device should be refcounted. > * > - * Drivers for USB interfaces should normally record such references in > - * their probe() methods, when they bind to an interface, and release > - * them by calling usb_put_dev(), in their disconnect() methods. > + * The device driver core automatically handles this refcounting for USB > + * interface drivers, but this API can be used for non-parent/child > + * relationships. > * > * Return: A pointer to the device with the incremented reference counter. > */ > -- > 2.8.0.rc3.226.g39d4020 > -- Dmitry
[RFC PATCH] usb: core: correct usb_get_dev() documentation
In reading through a USB interface driver, I noticed that it called usb_{get,put}_dev() in its probe() and disconnect() methods. This seemed unnecessary, but a look at the comments here matched the usage. USB interface devices seem to be well covered by the parent/child relationship of the device model, and so it should be unnecessary for a child device to grab a refcount on its parent device. Signed-off-by: Brian Norris--- This reflects my understanding (and testing), as well as the majority of usage -- there are *very* few interface drivers that actually call usb_get_dev(). If I'm wrong, please feel free to tell me so! But I thought patching the documentation would be the best way to solicit a response :) drivers/usb/core/usb.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c index 592151461017..0ba7e070f04e 100644 --- a/drivers/usb/core/usb.c +++ b/drivers/usb/core/usb.c @@ -539,9 +539,9 @@ EXPORT_SYMBOL_GPL(usb_alloc_dev); * * Each live reference to a device should be refcounted. * - * Drivers for USB interfaces should normally record such references in - * their probe() methods, when they bind to an interface, and release - * them by calling usb_put_dev(), in their disconnect() methods. + * The device driver core automatically handles this refcounting for USB + * interface drivers, but this API can be used for non-parent/child + * relationships. * * Return: A pointer to the device with the incremented reference counter. */ -- 2.8.0.rc3.226.g39d4020
[RFC PATCH] usb: core: correct usb_get_dev() documentation
In reading through a USB interface driver, I noticed that it called usb_{get,put}_dev() in its probe() and disconnect() methods. This seemed unnecessary, but a look at the comments here matched the usage. USB interface devices seem to be well covered by the parent/child relationship of the device model, and so it should be unnecessary for a child device to grab a refcount on its parent device. Signed-off-by: Brian Norris --- This reflects my understanding (and testing), as well as the majority of usage -- there are *very* few interface drivers that actually call usb_get_dev(). If I'm wrong, please feel free to tell me so! But I thought patching the documentation would be the best way to solicit a response :) drivers/usb/core/usb.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c index 592151461017..0ba7e070f04e 100644 --- a/drivers/usb/core/usb.c +++ b/drivers/usb/core/usb.c @@ -539,9 +539,9 @@ EXPORT_SYMBOL_GPL(usb_alloc_dev); * * Each live reference to a device should be refcounted. * - * Drivers for USB interfaces should normally record such references in - * their probe() methods, when they bind to an interface, and release - * them by calling usb_put_dev(), in their disconnect() methods. + * The device driver core automatically handles this refcounting for USB + * interface drivers, but this API can be used for non-parent/child + * relationships. * * Return: A pointer to the device with the incremented reference counter. */ -- 2.8.0.rc3.226.g39d4020