| Message ID | 20191009134342.6476-3-hadess@hadess.net (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Add Apple MFi fastcharge USB device driver | expand |
On Wed, 9 Oct 2019, Bastien Nocera wrote: > The kernel currenly has only 2 usb_device_drivers, one generic one, one > that completely replaces the generic one to make USB devices usable over > a network. Presumably your first driver is in generic.c. Where is the second one? > Use the newly exported generic driver functions when a driver declares > to want them run, in addition to its own code. This makes it possible to > write drivers that extend the generic USB driver. > > Signed-off-by: Bastien Nocera <hadess@hadess.net> This has a few problems. The biggest one is that the device core does not guarantee any order of driver probing. If generic.c is probed first, the subclass driver will never get probed -- which is a pretty fatal flaw. > --- > drivers/usb/core/driver.c | 36 ++++++++++++++++++++++++++++++------ > include/linux/usb.h | 1 + > 2 files changed, 31 insertions(+), 6 deletions(-) > > diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c > index 2b27d232d7a7..863e380a272b 100644 > --- a/drivers/usb/core/driver.c > +++ b/drivers/usb/core/driver.c > @@ -261,10 +261,17 @@ static int usb_probe_device(struct device *dev) > */ > if (!udriver->supports_autosuspend) > error = usb_autoresume_device(udev); > + if (error) > + return error; > > - if (!error) > - error = udriver->probe(udev); > - return error; > + if (udriver->generic_init) > + error = usb_generic_driver_probe(udev); > + if (error) > + return error; > + > + if (udriver->probe) > + return udriver->probe(udev); > + return 0; > } > > /* called from driver core with dev locked */ > @@ -273,7 +280,10 @@ static int usb_unbind_device(struct device *dev) > struct usb_device *udev = to_usb_device(dev); > struct usb_device_driver *udriver = to_usb_device_driver(dev->driver); > > - udriver->disconnect(udev); > + if (udriver->generic_init) > + usb_generic_driver_disconnect(udev); > + if (udriver->disconnect) > + udriver->disconnect(udev); The order is wrong. The disconnects should always be done in reverse order of probing. This is true whenever you have a destructor for a subclass; the subclasses destructor runs before the superclass's destructor. > if (!udriver->supports_autosuspend) > usb_autosuspend_device(udev); > return 0; > @@ -886,6 +896,14 @@ int usb_register_device_driver(struct usb_device_driver *new_udriver, > if (usb_disabled()) > return -ENODEV; > > + if (new_udriver->probe == NULL && > + !new_udriver->generic_init) { There's no point adding this extra test. Even subclass drivers should have a probe function. > + printk(KERN_ERR "%s: error %d registering device " > + " driver %s, no probe() function\n", Don't split character strings. They are an exception to the 80-column limit. > + usbcore_name, retval, new_udriver->name); > + return -EINVAL; > + } > + > new_udriver->drvwrap.for_devices = 1; > new_udriver->drvwrap.driver.name = new_udriver->name; > new_udriver->drvwrap.driver.bus = &usb_bus_type; > @@ -1149,7 +1167,10 @@ static int usb_suspend_device(struct usb_device *udev, pm_message_t msg) > udev->do_remote_wakeup = 0; > udriver = &usb_generic_driver; > } > - status = udriver->suspend(udev, msg); > + if (udriver->generic_init) > + status = usb_generic_driver_suspend (udev, msg); > + if (status == 0 && udriver->suspend) > + status = udriver->suspend(udev, msg); Again, the order is wrong. Suspend the subclass driver first. > done: > dev_vdbg(&udev->dev, "%s: status %d\n", __func__, status); > @@ -1181,7 +1202,10 @@ static int usb_resume_device(struct usb_device *udev, pm_message_t msg) > udev->reset_resume = 1; > > udriver = to_usb_device_driver(udev->dev.driver); > - status = udriver->resume(udev, msg); > + if (udriver->generic_init) > + status = usb_generic_driver_resume (udev, msg); > + if (status == 0 && udriver->resume) > + status = udriver->resume(udev, msg); > > done: > dev_vdbg(&udev->dev, "%s: status %d\n", __func__, status); > diff --git a/include/linux/usb.h b/include/linux/usb.h > index e656e7b4b1e4..fb9ad3511e55 100644 > --- a/include/linux/usb.h > +++ b/include/linux/usb.h > @@ -1242,6 +1242,7 @@ struct usb_device_driver { > const struct attribute_group **dev_groups; > struct usbdrv_wrap drvwrap; > unsigned int supports_autosuspend:1; > + unsigned int generic_init:1; How about using a name that actually says something about the driver? Such as generic_subclass? Or subclass_of_generic? "init" has nothing to do with anything. > }; > #define to_usb_device_driver(d) container_of(d, struct usb_device_driver, \ > drvwrap.driver) Alan Stern
On Wed, 9 Oct 2019, Alan Stern wrote: > On Wed, 9 Oct 2019, Bastien Nocera wrote: > > > The kernel currenly has only 2 usb_device_drivers, one generic one, one > > that completely replaces the generic one to make USB devices usable over > > a network. > > Presumably your first driver is in generic.c. Where is the second one? > > > Use the newly exported generic driver functions when a driver declares > > to want them run, in addition to its own code. This makes it possible to > > write drivers that extend the generic USB driver. > > > > Signed-off-by: Bastien Nocera <hadess@hadess.net> > > This has a few problems. The biggest one is that the device core does > not guarantee any order of driver probing. If generic.c is probed > first, the subclass driver will never get probed -- which is a pretty > fatal flaw. I wrote this before reading patch 4/5. So the situation isn't so bad. Alan Stern
More replies inline (which I always miss) On Wed, 2019-10-09 at 10:34 -0400, Alan Stern wrote: > On Wed, 9 Oct 2019, Bastien Nocera wrote: > > > The kernel currenly has only 2 usb_device_drivers, one generic one, > one > > that completely replaces the generic one to make USB devices usable > over > > a network. > > Presumably your first driver is in generic.c. Where is the second > one? > > > Use the newly exported generic driver functions when a driver > declares > > to want them run, in addition to its own code. This makes it > possible to > > write drivers that extend the generic USB driver. > > > > Signed-off-by: Bastien Nocera <hadess@hadess.net> > > This has a few problems. The biggest one is that the device core > does > not guarantee any order of driver probing. If generic.c is probed > first, the subclass driver will never get probed -- which is a > pretty > fatal flaw. > > > --- > > drivers/usb/core/driver.c | 36 ++++++++++++++++++++++++++++++----- > - > > include/linux/usb.h | 1 + > > 2 files changed, 31 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c > > index 2b27d232d7a7..863e380a272b 100644 > > --- a/drivers/usb/core/driver.c > > +++ b/drivers/usb/core/driver.c > > @@ -261,10 +261,17 @@ static int usb_probe_device(struct device > *dev) > > */ > > if (!udriver->supports_autosuspend) > > error = usb_autoresume_device(udev); > > + if (error) > > + return error; > > > > - if (!error) > > - error = udriver->probe(udev); > > - return error; > > + if (udriver->generic_init) > > + error = usb_generic_driver_probe(udev); > > + if (error) > > + return error; > > + > > + if (udriver->probe) > > + return udriver->probe(udev); > > + return 0; > > } > > > > /* called from driver core with dev locked */ > > @@ -273,7 +280,10 @@ static int usb_unbind_device(struct device > *dev) > > struct usb_device *udev = to_usb_device(dev); > > struct usb_device_driver *udriver = to_usb_device_driver(dev- > >driver); > > > > - udriver->disconnect(udev); > > + if (udriver->generic_init) > > + usb_generic_driver_disconnect(udev); > > + if (udriver->disconnect) > > + udriver->disconnect(udev); > > The order is wrong. The disconnects should always be done in > reverse > order of probing. This is true whenever you have a destructor for a > subclass; the subclasses destructor runs before the superclass's > destructor. Fixed. Fixed in the suspend function as well. > > if (!udriver->supports_autosuspend) > > usb_autosuspend_device(udev); > > return 0; > > @@ -886,6 +896,14 @@ int usb_register_device_driver(struct > usb_device_driver *new_udriver, > > if (usb_disabled()) > > return -ENODEV; > > > > + if (new_udriver->probe == NULL && > > + !new_udriver->generic_init) { > > There's no point adding this extra test. Even subclass drivers > should > have a probe function. Removed. > > + printk(KERN_ERR "%s: error %d registering device " > > + " driver %s, no probe() function\n", > > Don't split character strings. They are an exception to the 80- > column > limit. I was using the error message just below in the function as an example. A bad one apparently. This is gone in any case. > > + usbcore_name, retval, new_udriver->name); > > + return -EINVAL; > > + } > > + > > new_udriver->drvwrap.for_devices = 1; > > new_udriver->drvwrap.driver.name = new_udriver->name; > > new_udriver->drvwrap.driver.bus = &usb_bus_type; > > @@ -1149,7 +1167,10 @@ static int usb_suspend_device(struct > usb_device *udev, pm_message_t msg) > > udev->do_remote_wakeup = 0; > > udriver = &usb_generic_driver; > > } > > - status = udriver->suspend(udev, msg); > > + if (udriver->generic_init) > > + status = usb_generic_driver_suspend (udev, msg); > > + if (status == 0 && udriver->suspend) > > + status = udriver->suspend(udev, msg); > > Again, the order is wrong. Suspend the subclass driver first. Done, as mentioned above. > > done: > > dev_vdbg(&udev->dev, "%s: status %d\n", __func__, status); > > @@ -1181,7 +1202,10 @@ static int usb_resume_device(struct > usb_device *udev, pm_message_t msg) > > udev->reset_resume = 1; > > > > udriver = to_usb_device_driver(udev->dev.driver); > > - status = udriver->resume(udev, msg); > > + if (udriver->generic_init) > > + status = usb_generic_driver_resume (udev, msg); > > + if (status == 0 && udriver->resume) > > + status = udriver->resume(udev, msg); > > > > done: > > dev_vdbg(&udev->dev, "%s: status %d\n", __func__, status); > > diff --git a/include/linux/usb.h b/include/linux/usb.h > > index e656e7b4b1e4..fb9ad3511e55 100644 > > --- a/include/linux/usb.h > > +++ b/include/linux/usb.h > > @@ -1242,6 +1242,7 @@ struct usb_device_driver { > > const struct attribute_group **dev_groups; > > struct usbdrv_wrap drvwrap; > > unsigned int supports_autosuspend:1; > > + unsigned int generic_init:1; > > How about using a name that actually says something about the > driver? > Such as generic_subclass? Or subclass_of_generic? > > "init" has nothing to do with anything. generic_subclass it will be. I've also documented it in the header. > > }; > > #define to_usb_device_driver(d) container_of(d, struct > usb_device_driver, \ > > drvwrap.driver) > > Alan Stern >
diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c index 2b27d232d7a7..863e380a272b 100644 --- a/drivers/usb/core/driver.c +++ b/drivers/usb/core/driver.c @@ -261,10 +261,17 @@ static int usb_probe_device(struct device *dev) */ if (!udriver->supports_autosuspend) error = usb_autoresume_device(udev); + if (error) + return error; - if (!error) - error = udriver->probe(udev); - return error; + if (udriver->generic_init) + error = usb_generic_driver_probe(udev); + if (error) + return error; + + if (udriver->probe) + return udriver->probe(udev); + return 0; } /* called from driver core with dev locked */ @@ -273,7 +280,10 @@ static int usb_unbind_device(struct device *dev) struct usb_device *udev = to_usb_device(dev); struct usb_device_driver *udriver = to_usb_device_driver(dev->driver); - udriver->disconnect(udev); + if (udriver->generic_init) + usb_generic_driver_disconnect(udev); + if (udriver->disconnect) + udriver->disconnect(udev); if (!udriver->supports_autosuspend) usb_autosuspend_device(udev); return 0; @@ -886,6 +896,14 @@ int usb_register_device_driver(struct usb_device_driver *new_udriver, if (usb_disabled()) return -ENODEV; + if (new_udriver->probe == NULL && + !new_udriver->generic_init) { + printk(KERN_ERR "%s: error %d registering device " + " driver %s, no probe() function\n", + usbcore_name, retval, new_udriver->name); + return -EINVAL; + } + new_udriver->drvwrap.for_devices = 1; new_udriver->drvwrap.driver.name = new_udriver->name; new_udriver->drvwrap.driver.bus = &usb_bus_type; @@ -1149,7 +1167,10 @@ static int usb_suspend_device(struct usb_device *udev, pm_message_t msg) udev->do_remote_wakeup = 0; udriver = &usb_generic_driver; } - status = udriver->suspend(udev, msg); + if (udriver->generic_init) + status = usb_generic_driver_suspend (udev, msg); + if (status == 0 && udriver->suspend) + status = udriver->suspend(udev, msg); done: dev_vdbg(&udev->dev, "%s: status %d\n", __func__, status); @@ -1181,7 +1202,10 @@ static int usb_resume_device(struct usb_device *udev, pm_message_t msg) udev->reset_resume = 1; udriver = to_usb_device_driver(udev->dev.driver); - status = udriver->resume(udev, msg); + if (udriver->generic_init) + status = usb_generic_driver_resume (udev, msg); + if (status == 0 && udriver->resume) + status = udriver->resume(udev, msg); done: dev_vdbg(&udev->dev, "%s: status %d\n", __func__, status); diff --git a/include/linux/usb.h b/include/linux/usb.h index e656e7b4b1e4..fb9ad3511e55 100644 --- a/include/linux/usb.h +++ b/include/linux/usb.h @@ -1242,6 +1242,7 @@ struct usb_device_driver { const struct attribute_group **dev_groups; struct usbdrv_wrap drvwrap; unsigned int supports_autosuspend:1; + unsigned int generic_init:1; }; #define to_usb_device_driver(d) container_of(d, struct usb_device_driver, \ drvwrap.driver)
The kernel currenly has only 2 usb_device_drivers, one generic one, one that completely replaces the generic one to make USB devices usable over a network. Use the newly exported generic driver functions when a driver declares to want them run, in addition to its own code. This makes it possible to write drivers that extend the generic USB driver. Signed-off-by: Bastien Nocera <hadess@hadess.net> --- drivers/usb/core/driver.c | 36 ++++++++++++++++++++++++++++++------ include/linux/usb.h | 1 + 2 files changed, 31 insertions(+), 6 deletions(-)