USB: add reset_resume method

This patch (as918) introduces a new USB driver method: reset_resume.
It is called when a device needs to be reset as part of a resume
procedure (whether because of a device quirk or because of the
USB-Persist facility), thereby taking over a role formerly assigned to
the post_reset method.  As a consequence, post_reset no longer needs
an argument indicating whether it is being called as part of a
reset-resume.  This separation of functions makes the code clearer.

In addition, the pre_reset and post_reset method return types are
changed; they now must return an error code.  The return value is
unused at present, but at some later time we may unbind drivers and
re-probe if they encounter an error during reset handling.

The existing pre_reset and post_reset methods in the usbhid,
usb-storage, and hub drivers are updated to match the new
requirements.  For usbhid the post_reset routine is also used for
reset_resume (duplicate method pointers); for the other drivers a new
reset_resume routine is added.  The change to hub.c looks bigger than
it really is, because mark_children_for_reset_resume() gets moved down
next to the new hub_reset_resume() routine.

A minor change to usb-storage makes the usb_stor_report_bus_reset()
routine acquire the host lock instead of requiring the caller to hold
it already.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
CC: Matthew Dharm <mdharm-usb@one-eyed-alien.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 26 insertions, 10 deletions

diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index e227f64d5641..1ba19eaa1970 100644
--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -321,10 +321,14 @@ void usb_stor_report_device_reset(struct us_data *us)
 
 /* Report a driver-initiated bus reset to the SCSI layer.
  * Calling this for a SCSI-initiated reset is unnecessary but harmless.
- * The caller must own the SCSI host lock. */
+ * The caller must not own the SCSI host lock. */
 void usb_stor_report_bus_reset(struct us_data *us)
 {
-        scsi_report_bus_reset(us_to_host(us), 0);
+        struct Scsi_Host *host = us_to_host(us);
+
+        scsi_lock(host);
+        scsi_report_bus_reset(host, 0);
+        scsi_unlock(host);
 }
 
 /***********************************************************************
diff --git a/drivers/usb/storage/usb.c b/drivers/usb/storage/usb.c
index be4cd8fe4ce6..00521f1d6a6b 100644
--- a/drivers/usb/storage/usb.c
+++ b/drivers/usb/storage/usb.c
@@ -219,6 +219,20 @@ static int storage_resume(struct usb_interface *iface)
         return 0;
 }
 
+static int storage_reset_resume(struct usb_interface *iface)
+{
+        struct us_data *us = usb_get_intfdata(iface);
+
+        US_DEBUGP("%s\n", __FUNCTION__);
+
+        /* Report the reset to the SCSI core */
+        usb_stor_report_bus_reset(us);
+
+        /* FIXME: Notify the subdrivers that they need to reinitialize
+         * the device */
+        return 0;
+}
+
 #endif /* CONFIG_PM */
 
 /*
@@ -226,7 +240,7 @@ static int storage_resume(struct usb_interface *iface)
  * a USB port reset, whether from this driver or a different one.
  */
 
-static void storage_pre_reset(struct usb_interface *iface)
+static int storage_pre_reset(struct usb_interface *iface)
 {
         struct us_data *us = usb_get_intfdata(iface);
 
@@ -234,26 +248,23 @@ static void storage_pre_reset(struct usb_interface *iface)
 
         /* Make sure no command runs during the reset */
         mutex_lock(&us->dev_mutex);
+        return 0;
 }
 
-static void storage_post_reset(struct usb_interface *iface, int reset_resume)
+static int storage_post_reset(struct usb_interface *iface)
 {
         struct us_data *us = usb_get_intfdata(iface);
 
         US_DEBUGP("%s\n", __FUNCTION__);
 
         /* Report the reset to the SCSI core */
-        scsi_lock(us_to_host(us));
         usb_stor_report_bus_reset(us);
-        scsi_unlock(us_to_host(us));
 
         /* FIXME: Notify the subdrivers that they need to reinitialize
          * the device */
 
-        /* If this is a reset-resume then the pre_reset routine wasn't
-         * called, so we don't need to unlock the mutex. */
-        if (!reset_resume)
-                mutex_unlock(&us->dev_mutex);
+        mutex_unlock(&us->dev_mutex);
+        return 0;
 }
 
 /*
@@ -1061,6 +1072,7 @@ static struct usb_driver usb_storage_driver = {
 #ifdef CONFIG_PM
         .suspend =      storage_suspend,
         .resume =       storage_resume,
+        .reset_resume = storage_reset_resume,
 #endif
         .pre_reset =    storage_pre_reset,
         .post_reset =   storage_post_reset,