usb-storage: implement autosuspend

This patch (as930) implements autosuspend for usb-storage.  It is
adapted from a patch by Oliver Neukum.  Autosuspend is allowed except
during LUN scanning, resets, and command execution.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 9 insertions, 4 deletions

diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index 1ba19eaa1970..47e56079925d 100644
--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -285,10 +285,15 @@ static int device_reset(struct scsi_cmnd *srb)
 
         US_DEBUGP("%s called\n", __FUNCTION__);
 
-        /* lock the device pointers and do the reset */
-        mutex_lock(&(us->dev_mutex));
-        result = us->transport_reset(us);
-        mutex_unlock(&us->dev_mutex);
+        result = usb_autopm_get_interface(us->pusb_intf);
+        if (result == 0) {
+
+                /* lock the device pointers and do the reset */
+                mutex_lock(&(us->dev_mutex));
+                result = us->transport_reset(us);
+                mutex_unlock(&us->dev_mutex);
+                usb_autopm_put_interface(us->pusb_intf);
+        }
 
         return result < 0 ? FAILED : SUCCESS;
 }