USB: check serial-number string after device reset

This patch (as1048) extends the descriptor checking after a device is
reset.  Now the SerialNumber string descriptor is compared to its old
value, in addition to the device and configuration descriptors.

As a consequence, the kmalloc() call in usb_string() is now on the
error-handling pathway for usb-storage.  Hence its allocation type is
changed to GFO_NOIO.

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

1 files changed, 4 insertions, 4 deletions

diff --git a/Documentation/usb/persist.txt b/Documentation/usb/persist.txt
index bea58db..d56cb1a 100644
--- a/Documentation/usb/persist.txt
+++ b/Documentation/usb/persist.txt
@@ -136,10 +136,10 @@ aren't guaranteed to be 100% accurate.
 
 If you replace one USB device with another of the same type (same
 manufacturer, same IDs, and so on) there's an excellent chance the
-kernel won't detect the change.  Serial numbers and other strings are
-not compared.  In many cases it wouldn't help if they were, because
-manufacturers frequently omit serial numbers entirely in their
-devices.
+kernel won't detect the change.  The serial number string and other
+descriptors are compared with the kernel's stored values, but this
+might not help since manufacturers frequently omit serial numbers
+entirely in their devices.
 
 Furthermore it's quite possible to leave a USB device exactly the same
 while changing its media.  If you replace the flash memory card in a