1 files changed, 31 insertions, 59 deletions

diff --git a/drivers/usb/storage/usb.c b/drivers/usb/storage/usb.c
index 3dd7da9fd504..db51ba16dc07 100644
--- a/drivers/usb/storage/usb.c
+++ b/drivers/usb/storage/usb.c
@@ -788,15 +788,19 @@ static void quiesce_and_remove_host(struct us_data *us)
         struct Scsi_Host *host = us_to_host(us);
 
         /* If the device is really gone, cut short reset delays */
-        if (us->pusb_dev->state == USB_STATE_NOTATTACHED)
+        if (us->pusb_dev->state == USB_STATE_NOTATTACHED) {
                 set_bit(US_FLIDX_DISCONNECTING, &us->dflags);
+                wake_up(&us->delay_wait);
+        }
 
-        /* Prevent SCSI-scanning (if it hasn't started yet)
-         * and wait for the SCSI-scanning thread to stop.
+        /* Prevent SCSI scanning (if it hasn't started yet)
+         * or wait for the SCSI-scanning routine to stop.
          */
-        set_bit(US_FLIDX_DONT_SCAN, &us->dflags);
-        wake_up(&us->delay_wait);
-        wait_for_completion(&us->scanning_done);
+        cancel_delayed_work_sync(&us->scan_dwork);
+
+        /* Balance autopm calls if scanning was cancelled */
+        if (test_bit(US_FLIDX_SCAN_PENDING, &us->dflags))
+                usb_autopm_put_interface_no_suspend(us->pusb_intf);
 
         /* Removing the host will perform an orderly shutdown: caches
          * synchronized, disks spun down, etc.
@@ -823,53 +827,28 @@ static void release_everything(struct us_data *us)
         scsi_host_put(us_to_host(us));
 }
 
-/* Thread to carry out delayed SCSI-device scanning */
-static int usb_stor_scan_thread(void * __us)
+/* Delayed-work routine to carry out SCSI-device scanning */
+static void usb_stor_scan_dwork(struct work_struct *work)
 {
-        struct us_data *us = (struct us_data *)__us;
+        struct us_data *us = container_of(work, struct us_data,
+                        scan_dwork.work);
         struct device *dev = &us->pusb_intf->dev;
 
-        dev_dbg(dev, "device found\n");
-
-        set_freezable();
+        dev_dbg(dev, "starting scan\n");
 
-        /*
-         * Wait for the timeout to expire or for a disconnect
-         *
-         * We can't freeze in this thread or we risk causing khubd to
-         * fail to freeze, but we can't be non-freezable either. Nor can
-         * khubd freeze while waiting for scanning to complete as it may
-         * hold the device lock, causing a hang when suspending devices.
-         * So instead of using wait_event_freezable(), explicitly test
-         * for (DONT_SCAN || freezing) in interruptible wait and proceed
-         * if any of DONT_SCAN, freezing or timeout has happened.
-         */
-        if (delay_use > 0) {
-                dev_dbg(dev, "waiting for device to settle "
-                                "before scanning\n");
-                wait_event_interruptible_timeout(us->delay_wait,
-                                test_bit(US_FLIDX_DONT_SCAN, &us->dflags) ||
-                                freezing(current), delay_use * HZ);
+        /* For bulk-only devices, determine the max LUN value */
+        if (us->protocol == USB_PR_BULK && !(us->fflags & US_FL_SINGLE_LUN)) {
+                mutex_lock(&us->dev_mutex);
+                us->max_lun = usb_stor_Bulk_max_lun(us);
+                mutex_unlock(&us->dev_mutex);
         }
+        scsi_scan_host(us_to_host(us));
+        dev_dbg(dev, "scan complete\n");
 
-        /* If the device is still connected, perform the scanning */
-        if (!test_bit(US_FLIDX_DONT_SCAN, &us->dflags)) {
-
-                /* For bulk-only devices, determine the max LUN value */
-                if (us->protocol == USB_PR_BULK &&
-                                !(us->fflags & US_FL_SINGLE_LUN)) {
-                        mutex_lock(&us->dev_mutex);
-                        us->max_lun = usb_stor_Bulk_max_lun(us);
-                        mutex_unlock(&us->dev_mutex);
-                }
-                scsi_scan_host(us_to_host(us));
-                dev_dbg(dev, "scan complete\n");
-
-                /* Should we unbind if no devices were detected? */
-        }
+        /* Should we unbind if no devices were detected? */
 
         usb_autopm_put_interface(us->pusb_intf);
-        complete_and_exit(&us->scanning_done, 0);
+        clear_bit(US_FLIDX_SCAN_PENDING, &us->dflags);
 }
 
 static unsigned int usb_stor_sg_tablesize(struct usb_interface *intf)
@@ -916,7 +895,7 @@ int usb_stor_probe1(struct us_data **pus,
         init_completion(&us->cmnd_ready);
         init_completion(&(us->notify));
         init_waitqueue_head(&us->delay_wait);
-        init_completion(&us->scanning_done);
+        INIT_DELAYED_WORK(&us->scan_dwork, usb_stor_scan_dwork);
 
         /* Associate the us_data structure with the USB device */
         result = associate_dev(us, intf);
@@ -947,7 +926,6 @@ EXPORT_SYMBOL_GPL(usb_stor_probe1);
 /* Second part of general USB mass-storage probing */
 int usb_stor_probe2(struct us_data *us)
 {
-        struct task_struct *th;
         int result;
         struct device *dev = &us->pusb_intf->dev;
 
@@ -988,20 +966,14 @@ int usb_stor_probe2(struct us_data *us)
                 goto BadDevice;
         }
 
-        /* Start up the thread for delayed SCSI-device scanning */
-        th = kthread_create(usb_stor_scan_thread, us, "usb-stor-scan");
-        if (IS_ERR(th)) {
-                dev_warn(dev,
-                                "Unable to start the device-scanning thread\n");
-                complete(&us->scanning_done);
-                quiesce_and_remove_host(us);
-                result = PTR_ERR(th);
-                goto BadDevice;
-        }
-
+        /* Submit the delayed_work for SCSI-device scanning */
         usb_autopm_get_interface_no_resume(us->pusb_intf);
-        wake_up_process(th);
+        set_bit(US_FLIDX_SCAN_PENDING, &us->dflags);
 
+        if (delay_use > 0)
+                dev_dbg(dev, "waiting for device to settle before scanning\n");
+        queue_delayed_work(system_freezable_wq, &us->scan_dwork,
+                        delay_use * HZ);
         return 0;
 
         /* We come here if there are any problems */