Introduce a new utility function to be able to reset a device from
interrupt context using a workqueue. If a reset is already pending, it
won't schedule another one.
Signed-off-by: Inaky Perez-Gonzalez <[EMAIL PROTECTED]>
---
drivers/usb/core/hub.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/usb.h | 2 +
2 files changed, 94 insertions(+)
Index: linux.hg/include/linux/usb.h
===================================================================
--- linux.hg.orig/include/linux/usb.h 2007-07-18 10:05:50.000000000 -0700
+++ linux.hg/include/linux/usb.h 2007-07-18 10:05:50.000000000 -0700
@@ -374,6 +374,7 @@
unsigned authorized:1; /* Policy has determined we can use it
*/
unsigned authenticated:1; /* Crypto authentication passed */
unsigned wusb:1; /* Device is Wireless USB */
+ unsigned delayed_reset:1; /* Delayed reset in progress */
int string_langid; /* language ID for strings */
/* static strings from the device */
@@ -431,6 +432,7 @@
extern int usb_reset_device(struct usb_device *dev);
extern int usb_reset_composite_device(struct usb_device *dev,
struct usb_interface *iface);
+extern void usb_dev_reset_delayed(struct usb_device *usb_dev);
extern struct usb_device *usb_find_device(u16 vendor_id, u16 product_id);
Index: linux.hg/drivers/usb/core/hub.c
===================================================================
--- linux.hg.orig/drivers/usb/core/hub.c 2007-07-18 10:05:50.000000000
-0700
+++ linux.hg/drivers/usb/core/hub.c 2007-07-18 10:05:50.000000000 -0700
@@ -3258,3 +3258,95 @@
return ret;
}
EXPORT_SYMBOL(usb_reset_composite_device);
+
+
+/* Support for delayed resets */
+struct usb_dev_reset_ctx {
+ struct work_struct ws;
+ struct usb_device *usb_dev;
+};
+
+
+/*
+ * We need to lock the device before resetting, but we may already have the
+ * lock. So we try to lock the device, if it fails (returns < 0) then we
+ * cannot proceed. If it returned 1 then we acquired the lock here and need
+ * to release the lock. If it returned 0 then we already have the lock and
+ * we leave it to the piece that acquired the lock to release it.
+ */
+static
+void usb_dev_reset_delayed_task(struct work_struct *ws)
+{
+ struct usb_dev_reset_ctx *reset_ctx =
+ container_of(ws, struct usb_dev_reset_ctx, ws);
+ struct usb_device *usb_dev = reset_ctx->usb_dev;
+ struct device *dev = &usb_dev->dev;
+ int had_to_lock;
+ int result = 0;
+
+ if (usb_dev == NULL) {
+ WARN_ON(1);
+ goto release;
+ }
+ had_to_lock = usb_lock_device_for_reset(usb_dev, NULL);
+ if (had_to_lock < 0) {
+ if (had_to_lock != -ENODEV) // ignore dissapearance
+ dev_err(dev, "Cannot lock device for reset: %d\n",
+ had_to_lock);
+ } else {
+ result = usb_reset_device(usb_dev);
+ if (result < 0 && result != -ENODEV)
+ dev_err(dev, "Unable to reset device: %d\n", result);
+ if (had_to_lock)
+ usb_unlock_device(usb_dev);
+ }
+ usb_dev->delayed_reset = 0;
+ usb_put_dev(usb_dev);
+release:
+ kfree(reset_ctx);
+ module_put(THIS_MODULE);
+}
+
+
+/**
+ * Schedule a delayed USB device reset
+ *
+ * @usb_dev: USB device that needs to be reset. We assume you have a
+ * valid reference on it (so it won't dissapear) until we
+ * take another one that we'll own.
+ *
+ * Allocates a context structure containing a workqueue struct with
+ * all the pertinent info; gets a reference to @usb_dev and schedules
+ * the call that will be executed later on.
+ *
+ * NOTE: for use in atomic contexts
+ */
+void usb_dev_reset_delayed(struct usb_device *usb_dev)
+{
+ struct usb_dev_reset_ctx *reset_ctx;
+ struct device *dev = &usb_dev->dev;
+ reset_ctx = kmalloc(sizeof(*reset_ctx), GFP_ATOMIC);
+ if (reset_ctx == NULL) {
+ if (printk_ratelimit())
+ dev_err(dev, "USB: cannot allocate memory for "
+ "delayed device reset\n");
+ return;
+ }
+ if (try_module_get(THIS_MODULE) == 0)
+ goto error_module_get;
+ usb_get_dev(usb_dev);
+ if (usb_dev->delayed_reset)
+ goto error_pending;
+ usb_dev->delayed_reset = 1;
+ reset_ctx->usb_dev = usb_dev;
+ INIT_WORK(&reset_ctx->ws, usb_dev_reset_delayed_task);
+ schedule_work(&reset_ctx->ws);
+ return;
+
+error_pending:
+ usb_put_dev(usb_dev);
+error_module_get:
+ kfree(reset_ctx);
+ return;
+}
+EXPORT_SYMBOL_GPL(usb_dev_reset_delayed);
--
Inaky
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