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 <balbi@xxxxxx>
> > ---
> >
> > 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 <balbi@xxxxxx>
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 <balbi@xxxxxx>
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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