usb-storage: implement "soft" unbinding

This patch (as1092) implements "soft" unbinding for usb-storage.  When
the disconnect routine is called, all commands and reset delays are
allowed to complete normally until after scsi_remove_host() returns.
This means that the commands needed for an orderly shutdown will be
sent through to the device.

Unlike before, the driver will now execute every command that it
accepts.  Hence there's no need for special code to catch unexecuted
commands and fail them.

The new sequence of events when disconnect runs goes as follows:

	If the device is truly unplugged, set the DISCONNECTING
	flag so we won't try to access it any more.

	If the SCSI-scanning thread hasn't started up yet, prevent
	it from doing anything by setting the new DONT_SCAN flag.
	Then wake it up and wait for it to terminate.

	Remove the SCSI host.  This unbinds the upper-level drivers,
	doing an orderly shutdown.  Commands sent to quiesce the
	device will be transmitted normally, unless the device is
	unplugged.

	Set the DISCONNECTING flag so that we won't accept any new
	commands that might get submitted (there aren't supposed to be
	any) and we won't try to access the device for resets.

	Tell the control thread to exit by waking it up with no
	pending command, and wait for it to terminate.

	Go on to do all the other normal stuff: releasing resources,
	freeing memory, and so on.

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

1 files changed, 8 insertions, 8 deletions

diff --git a/drivers/usb/storage/transport.c b/drivers/usb/storage/transport.c
index 2f88bb958ba..94138df557b 100644
--- a/drivers/usb/storage/transport.c
+++ b/drivers/usb/storage/transport.c
@@ -127,8 +127,8 @@ static int usb_stor_msg_common(struct us_data *us, int timeout)
         long timeleft;
         int status;
 
-        /* don't submit URBs during abort/disconnect processing */
-        if (us->dflags & ABORTING_OR_DISCONNECTING)
+        /* don't submit URBs during abort processing */
+        if (test_bit(US_FLIDX_ABORTING, &us->dflags))
                 return -EIO;
 
         /* set up data structures for the wakeup system */
@@ -161,8 +161,8 @@ static int usb_stor_msg_common(struct us_data *us, int timeout)
          * to cancel it */
         set_bit(US_FLIDX_URB_ACTIVE, &us->dflags);
 
-        /* did an abort/disconnect occur during the submission? */
-        if (us->dflags & ABORTING_OR_DISCONNECTING) {
+        /* did an abort occur during the submission? */
+        if (test_bit(US_FLIDX_ABORTING, &us->dflags)) {
 
                 /* cancel the URB, if it hasn't been cancelled already */
                 if (test_and_clear_bit(US_FLIDX_URB_ACTIVE, &us->dflags)) {
@@ -419,8 +419,8 @@ static int usb_stor_bulk_transfer_sglist(struct us_data *us, unsigned int pipe,
 {
         int result;
 
-        /* don't submit s-g requests during abort/disconnect processing */
-        if (us->dflags & ABORTING_OR_DISCONNECTING)
+        /* don't submit s-g requests during abort processing */
+        if (test_bit(US_FLIDX_ABORTING, &us->dflags))
                 return USB_STOR_XFER_ERROR;
 
         /* initialize the scatter-gather request block */
@@ -437,8 +437,8 @@ static int usb_stor_bulk_transfer_sglist(struct us_data *us, unsigned int pipe,
          * okay to cancel it */
         set_bit(US_FLIDX_SG_ACTIVE, &us->dflags);
 
-        /* did an abort/disconnect occur during the submission? */
-        if (us->dflags & ABORTING_OR_DISCONNECTING) {
+        /* did an abort occur during the submission? */
+        if (test_bit(US_FLIDX_ABORTING, &us->dflags)) {
 
                 /* cancel the request, if it hasn't been cancelled already */
                 if (test_and_clear_bit(US_FLIDX_SG_ACTIVE, &us->dflags)) {