USB: use reset_resume when normal resume fails

This patch (as1109b) makes USB-Persist more resilient to errors.  With
the current code, if a normal resume fails, it's an unrecoverable
error.  With the patch, if a normal resume fails (and if the device is
enabled for USB-Persist) then a reset-resume is tried.

This fixes the problem reported in Bugzilla #10977.

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

1 files changed, 17 insertions, 3 deletions

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index f1efabbc1ca2..107e1d25ddec 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -1822,9 +1822,15 @@ static int check_port_resume_type(struct usb_device *udev,
                         status = -ENODEV;
         }
 
-        /* Can't do a normal resume if the port isn't enabled */
-        else if (!(portstatus & USB_PORT_STAT_ENABLE) && !udev->reset_resume)
-                status = -ENODEV;
+        /* Can't do a normal resume if the port isn't enabled,
+         * so try a reset-resume instead.
+         */
+        else if (!(portstatus & USB_PORT_STAT_ENABLE) && !udev->reset_resume) {
+                if (udev->persist_enabled)
+                        udev->reset_resume = 1;
+                else
+                        status = -ENODEV;
+        }
 
         if (status) {
                 dev_dbg(hub->intfdev,
@@ -1973,6 +1979,7 @@ static int finish_port_resume(struct usb_device *udev)
          * resumed.
          */
         if (udev->reset_resume)
+ retry_reset_resume:
                 status = usb_reset_and_verify_device(udev);
 
         /* 10.5.4.5 says be sure devices in the tree are still there.
@@ -1984,6 +1991,13 @@ static int finish_port_resume(struct usb_device *udev)
                 status = usb_get_status(udev, USB_RECIP_DEVICE, 0, &devstatus);
                 if (status >= 0)
                         status = (status > 0 ? 0 : -ENODEV);
+
+                /* If a normal resume failed, try doing a reset-resume */
+                if (status && !udev->reset_resume && udev->persist_enabled) {
+                        dev_dbg(&udev->dev, "retry with reset-resume\n");
+                        udev->reset_resume = 1;
+                        goto retry_reset_resume;
+                }
         }
 
         if (status) {