Hi, On Thu, Jul 18, 2013 at 09:53:22AM -0400, Alan Stern wrote: > On Thu, 18 Jul 2013, Felipe Balbi wrote: > > > usb_gadget_set_state() will call sysfs_notify() > > which might sleep. Some users might want to call > > usb_gadget_set_state() from the very IRQ handler > > which actually changes the gadget state. > > > > Instead of having every UDC driver add their own > > workqueue for such a simple notification, we're > > adding it generically to our struct usb_gadget, > > so the details are hidden from all UDC drivers. > > > > Signed-off-by: Felipe Balbi <[email protected]> > > --- > > > > Tested on OMAP5 uEVM. > > > > drivers/usb/gadget/udc-core.c | 11 ++++++++++- > > include/linux/usb/gadget.h | 4 ++++ > > 2 files changed, 14 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/usb/gadget/udc-core.c b/drivers/usb/gadget/udc-core.c > > index ffd8fa5..b0d91b1 100644 > > --- a/drivers/usb/gadget/udc-core.c > > +++ b/drivers/usb/gadget/udc-core.c > > @@ -23,6 +23,7 @@ > > #include <linux/list.h> > > #include <linux/err.h> > > #include <linux/dma-mapping.h> > > +#include <linux/workqueue.h> > > > > #include <linux/usb/ch9.h> > > #include <linux/usb/gadget.h> > > @@ -101,11 +102,18 @@ EXPORT_SYMBOL_GPL(usb_gadget_unmap_request); > > > > /* > > ------------------------------------------------------------------------- */ > > > > +static void usb_gadget_state_work(struct work_struct *work) > > +{ > > + struct usb_gadget *gadget = work_to_gadget(work); > > + > > + sysfs_notify(&gadget->dev.kobj, NULL, "status"); > > +} > > + > > void usb_gadget_set_state(struct usb_gadget *gadget, > > enum usb_device_state state) > > { > > gadget->state = state; > > - sysfs_notify(&gadget->dev.kobj, NULL, "status"); > > + schedule_work(&gadget->work); > > } > > EXPORT_SYMBOL_GPL(usb_gadget_set_state); > > > > @@ -192,6 +200,7 @@ int usb_add_gadget_udc_release(struct device *parent, > > struct usb_gadget *gadget, > > goto err1; > > > > dev_set_name(&gadget->dev, "gadget"); > > + INIT_WORK(&gadget->work, usb_gadget_state_work); > > gadget->dev.parent = parent; > > > > dma_set_coherent_mask(&gadget->dev, parent->coherent_dma_mask); > > Deallocation of the gadget structure races with the work routine. You > need to wait for any scheduled work to complete when the gadget is > unregistered.
indeed. Added a flush_work() call to usb_del_gadget_udc() > Also, what happens if two state transitions occur before the work queue > gets around to executing the work routine? do we need to care about that at all ? It's a queue anyway, transitions will still be notified in order. Here's a new diff: commit b2e025e9d347bd0858a50dbf222408c070d6801e Author: Felipe Balbi <[email protected]> Date: Wed Jul 17 11:09:49 2013 +0300 usb: gadget: udc-core: move sysfs_notify() to a workqueue usb_gadget_set_state() will call sysfs_notify() which might sleep. Some users might want to call usb_gadget_set_state() from the very IRQ handler which actually changes the gadget state. Instead of having every UDC driver add their own workqueue for such a simple notification, we're adding it generically to our struct usb_gadget, so the details are hidden from all UDC drivers. Signed-off-by: Felipe Balbi <[email protected]> diff --git a/drivers/usb/gadget/udc-core.c b/drivers/usb/gadget/udc-core.c index ffd8fa5..ee5a0fa 100644 --- a/drivers/usb/gadget/udc-core.c +++ b/drivers/usb/gadget/udc-core.c @@ -23,6 +23,7 @@ #include <linux/list.h> #include <linux/err.h> #include <linux/dma-mapping.h> +#include <linux/workqueue.h> #include <linux/usb/ch9.h> #include <linux/usb/gadget.h> @@ -101,11 +102,18 @@ EXPORT_SYMBOL_GPL(usb_gadget_unmap_request); /* ------------------------------------------------------------------------- */ +static void usb_gadget_state_work(struct work_struct *work) +{ + struct usb_gadget *gadget = work_to_gadget(work); + + sysfs_notify(&gadget->dev.kobj, NULL, "status"); +} + void usb_gadget_set_state(struct usb_gadget *gadget, enum usb_device_state state) { gadget->state = state; - sysfs_notify(&gadget->dev.kobj, NULL, "status"); + schedule_work(&gadget->work); } EXPORT_SYMBOL_GPL(usb_gadget_set_state); @@ -192,6 +200,7 @@ int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget, goto err1; dev_set_name(&gadget->dev, "gadget"); + INIT_WORK(&gadget->work, usb_gadget_state_work); gadget->dev.parent = parent; dma_set_coherent_mask(&gadget->dev, parent->coherent_dma_mask); @@ -311,6 +320,7 @@ found: kobject_uevent(&udc->dev.kobj, KOBJ_REMOVE); device_unregister(&udc->dev); device_unregister(&gadget->dev); + flush_work(&gadget->work); } EXPORT_SYMBOL_GPL(usb_del_gadget_udc); diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h index f1b0dca..942ef5e 100644 --- a/include/linux/usb/gadget.h +++ b/include/linux/usb/gadget.h @@ -22,6 +22,7 @@ #include <linux/slab.h> #include <linux/scatterlist.h> #include <linux/types.h> +#include <linux/workqueue.h> #include <linux/usb/ch9.h> struct usb_ep; @@ -475,6 +476,7 @@ struct usb_gadget_ops { /** * struct usb_gadget - represents a usb slave device + * @work: (internal use) Workqueue to be used for sysfs_notify() * @ops: Function pointers used to access hardware-specific operations. * @ep0: Endpoint zero, used when reading or writing responses to * driver setup() requests @@ -520,6 +522,7 @@ struct usb_gadget_ops { * device is acting as a B-Peripheral (so is_a_peripheral is false). */ struct usb_gadget { + struct work_struct work; /* readonly to gadget driver */ const struct usb_gadget_ops *ops; struct usb_ep *ep0; @@ -538,6 +541,7 @@ struct usb_gadget { unsigned out_epnum; unsigned in_epnum; }; +#define work_to_gadget(w) (container_of((w), struct usb_gadget, work)) static inline void set_gadget_data(struct usb_gadget *gadget, void *data) { dev_set_drvdata(&gadget->dev, data); } -- balbi
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