and races with scsi_destroy_sdev() <- scsi_sysfs_add_devices() <-
scsi_finish_async_scan().  The result is use after free and/or double
free, oops.

The fix is simple, move scsi_forget_host() under scan_mutex.

scsi_forget_host() is just sequence of __scsi_remove_device().  All
another calls of __scsi_remove_device() are made under scan_mutex.  So
that it is safe.
Signed-off-by: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>