[PATCH 4.2 078/110] xen-blkfront: check for null drvdata in blkback_changed (XenbusStateClosing)

4.2-stable review patch. If anyone has any objections, please let me know. -- From: Cathy Avery commit a54c8f0f2d7df525ff997e2afe71866a1a013064 upstream. xen-blkfront will crash if the check to talk_to_blkback() in blkback_changed()(XenbusStateInitWait) returns an error. The

[PATCH 4.2 078/110] xen-blkfront: check for null drvdata in blkback_changed (XenbusStateClosing)

4.2-stable review patch. If anyone has any objections, please let me know. -- From: Cathy Avery commit a54c8f0f2d7df525ff997e2afe71866a1a013064 upstream. xen-blkfront will crash if the check to talk_to_blkback() in