I just purchased a HighPoint Rocket 1520 SATA controller.  There seems to
be no libata driver (yet), but there is an ide driver, hpt366.  When the
driver gets loaded, it causes a kernel NULL pointer dereference in
pci_bus_clock_list.  It seems to be because the driver is waiting for clock
stabilization in init_hpt37x() which never comes.  The driver just
continues on with the pci drvdata set to NULL, instead of a valid clock
entry.  The following patch prevents the NULL dereference from happening,
but instead exit with an error.
Acked-by: Bartlomiej Zolnierkiewicz <B.Zolnierkiewicz@elka.pw.edu.pl>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>