Both a cleanup, as khubd open codes several facilities that are provided
by workqueue, and an enabling step for flushing initial port discovery
operations. A do { } while (0) loop in hub_event() is used to minimize
code thrash.
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
drivers/usb/core/hub.c | 146 ++++++++++++++++--------------------------------
drivers/usb/core/hub.h | 2 -
2 files changed, 51 insertions(+), 97 deletions(-)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 3c109924d2ae..e0518af66af9 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -22,11 +22,10 @@
#include <linux/usb/hcd.h>
#include <linux/usb/otg.h>
#include <linux/usb/quirks.h>
-#include <linux/kthread.h>
#include <linux/mutex.h>
-#include <linux/freezer.h>
#include <linux/random.h>
#include <linux/pm_qos.h>
+#include <linux/workqueue.h>
#include <asm/uaccess.h>
#include <asm/byteorder.h>
@@ -41,14 +40,10 @@
* change to USB_STATE_NOTATTACHED even when the semaphore isn't held. */
static DEFINE_SPINLOCK(device_state_lock);
-/* khubd's worklist and its lock */
+/* sync event queueing vs hub disconnects */
static DEFINE_SPINLOCK(hub_event_lock);
-static LIST_HEAD(hub_event_list); /* List of hubs needing servicing */
-/* Wakes up khubd */
-static DECLARE_WAIT_QUEUE_HEAD(khubd_wait);
-
-static struct task_struct *khubd_task;
+static struct workqueue_struct *khubd_wq;
/* cycle leds on hubs that aren't blinking for attention */
static bool blinkenlights = 0;
@@ -559,18 +554,28 @@ static int hub_port_status(struct usb_hub *hub, int port1,
return ret;
}
+static void hub_release(struct kref *kref)
+{
+ struct usb_hub *hub = container_of(kref, struct usb_hub, kref);
+
+ usb_put_intf(to_usb_interface(hub->intfdev));
+ kfree(hub);
+}
+
static void kick_khubd(struct usb_hub *hub)
{
- unsigned long flags;
+ struct usb_interface *intf = to_usb_interface(hub->intfdev);
+ unsigned long flags;
+ /* Suppress autosuspend until khubd runs */
spin_lock_irqsave(&hub_event_lock, flags);
- if (!hub->disconnected && list_empty(&hub->event_list)) {
- list_add_tail(&hub->event_list, &hub_event_list);
-
- /* Suppress autosuspend until khubd runs */
- usb_autopm_get_interface_no_resume(
- to_usb_interface(hub->intfdev));
- wake_up(&khubd_wait);
+ if (!hub->disconnected) {
+ usb_autopm_get_interface_no_resume(intf);
+ kref_get(&hub->kref);
+ if (!queue_work(khubd_wq, &hub->event_work)) {
+ usb_autopm_put_interface_async(intf);
+ kref_put(&hub->kref, hub_release);
+ }
}
spin_unlock_irqrestore(&hub_event_lock, flags);
}
@@ -1584,14 +1589,6 @@ fail_keep_maxchild:
return ret;
}
-static void hub_release(struct kref *kref)
-{
- struct usb_hub *hub = container_of(kref, struct usb_hub, kref);
-
- usb_put_intf(to_usb_interface(hub->intfdev));
- kfree(hub);
-}
-
static unsigned highspeed_hubs;
static void hub_disconnect(struct usb_interface *intf)
@@ -1600,13 +1597,13 @@ static void hub_disconnect(struct usb_interface *intf)
struct usb_device *hdev = interface_to_usbdev(intf);
int port1;
- /* Take the hub off the event list and don't let it be added again */
- spin_lock_irq(&hub_event_lock);
- if (!list_empty(&hub->event_list)) {
- list_del_init(&hub->event_list);
- usb_autopm_put_interface_no_suspend(intf);
- }
+ /*
+ * Disable hub event processing, note that we can't flush the work
+ * since we may be holding a device lock that khubd wants to acquire
+ * (lockdep is prevented from flagging this)
+ */
hub->disconnected = 1;
+ spin_lock_irq(&hub_event_lock);
spin_unlock_irq(&hub_event_lock);
/* Disconnect all children and quiesce the hub */
@@ -1636,6 +1633,8 @@ static void hub_disconnect(struct usb_interface *intf)
kref_put(&hub->kref, hub_release);
}
+static void hub_event(struct work_struct *);
+
static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
{
struct usb_host_interface *desc;
@@ -1726,7 +1725,7 @@ descriptor_error:
}
kref_init(&hub->kref);
- INIT_LIST_HEAD(&hub->event_list);
+ INIT_WORK(&hub->event_work, hub_event);
hub->intfdev = &intf->dev;
hub->hdev = hdev;
INIT_DELAYED_WORK(&hub->leds, led_work);
@@ -4828,42 +4827,16 @@ static void port_event(struct usb_hub *hub, int port1)
}
-static void hub_events(void)
+static void hub_event(struct work_struct *w)
{
- struct list_head *tmp;
- struct usb_device *hdev;
- struct usb_interface *intf;
- struct usb_hub *hub;
- struct device *hub_dev;
- u16 hubstatus;
- u16 hubchange;
+ struct usb_hub *hub = container_of(w, struct usb_hub, event_work);
int i, ret;
+ u16 hubstatus, hubchange;
+ struct usb_device *hdev = hub->hdev;
+ struct device *hub_dev = hub->intfdev;
+ struct usb_interface *intf = to_usb_interface(hub_dev);
- /*
- * We restart the list every time to avoid a deadlock with
- * deleting hubs downstream from this one. This should be
- * safe since we delete the hub from the event list.
- * Not the most efficient, but avoids deadlocks.
- */
- while (1) {
-
- /* Grab the first entry at the beginning of the list */
- spin_lock_irq(&hub_event_lock);
- if (list_empty(&hub_event_list)) {
- spin_unlock_irq(&hub_event_lock);
- break;
- }
-
- tmp = hub_event_list.next;
- list_del_init(tmp);
-
- hub = list_entry(tmp, struct usb_hub, event_list);
- kref_get(&hub->kref);
- spin_unlock_irq(&hub_event_lock);
-
- hdev = hub->hdev;
- hub_dev = hub->intfdev;
- intf = to_usb_interface(hub_dev);
+ do {
dev_dbg(hub_dev, "state %d ports %d chg %04x evt %04x\n",
hdev->state, hdev->maxchild,
/* NOTE: expects max 15 ports... */
@@ -4873,8 +4846,6 @@ static void hub_events(void)
/* Lock the device, then check to see if we were
* disconnected while waiting for the lock to succeed. */
usb_lock_device(hdev);
- if (unlikely(hub->disconnected))
- goto loop_disconnected;
/* If the hub has died, clean up after it */
if (hdev->state == USB_STATE_NOTATTACHED) {
@@ -4963,31 +4934,9 @@ static void hub_events(void)
* kick_khubd() and allow autosuspend.
*/
usb_autopm_put_interface(intf);
- loop_disconnected:
usb_unlock_device(hdev);
- kref_put(&hub->kref, hub_release);
-
- } /* end while (1) */
-}
-
-static int hub_thread(void *__unused)
-{
- /* khubd needs to be freezable to avoid interfering with USB-PERSIST
- * port handover. Otherwise it might see that a full-speed device
- * was gone before the EHCI controller had handed its port over to
- * the companion full-speed controller.
- */
- set_freezable();
-
- do {
- hub_events();
- wait_event_freezable(khubd_wait,
- !list_empty(&hub_event_list) ||
- kthread_should_stop());
- } while (!kthread_should_stop() || !list_empty(&hub_event_list));
-
- pr_debug("%s: khubd exiting\n", usbcore_name);
- return 0;
+ } while (0);
+ kref_put(&hub->kref, hub_release);
}
static const struct usb_device_id hub_id_table[] = {
@@ -5027,11 +4976,17 @@ int usb_hub_init(void)
return -1;
}
- khubd_task = kthread_run(hub_thread, NULL, "khubd");
- if (!IS_ERR(khubd_task))
+ /* khubd needs to be freezable to avoid interfering with USB-PERSIST
+ * port handover. Otherwise it might see that a full-speed device
+ * was gone before the EHCI controller had handed its port over to
+ * the companion full-speed controller.
+ */
+ khubd_wq = create_freezable_workqueue("khubd");
+
+ if (khubd_wq)
return 0;
- /* Fall through if kernel_thread failed */
+ /* Fall through if workqueue creation failed */
usb_deregister(&hub_driver);
printk(KERN_ERR "%s: can't start khubd\n", usbcore_name);
@@ -5040,8 +4995,6 @@ int usb_hub_init(void)
void usb_hub_cleanup(void)
{
- kthread_stop(khubd_task);
-
/*
* Hub resources are freed for us by usb_deregister. It calls
* usb_driver_purge on every device which in turn calls that
@@ -5050,7 +5003,8 @@ void usb_hub_cleanup(void)
* individual hub resources. -greg
*/
usb_deregister(&hub_driver);
-} /* usb_hub_cleanup() */
+ destroy_workqueue(khubd_wq);
+}
static int descriptors_changed(struct usb_device *udev,
struct usb_device_descriptor *old_device_descriptor,
diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
index 16d03486e8fc..96a058c8d85f 100644
--- a/drivers/usb/core/hub.h
+++ b/drivers/usb/core/hub.h
@@ -41,7 +41,7 @@ struct usb_hub {
int error; /* last reported error */
int nerrors; /* track consecutive errors */
- struct list_head event_list; /* hubs w/data or errs ready */
+ struct work_struct event_work; /* hubs w/data or errs ready */
unsigned long event_bits[1]; /* status change bitmask */
unsigned long change_bits[1]; /* ports with logical connect
status change */
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
