Mikulas Patocka dd7a738028 alpha: fix memory barriers so that they conform to the specification ... commit 54505a1e2083fc54cbe8779b97479f969cd30a00 upstream. The commits cd0e00c106 and 92d7223a74 broke boot on the Alpha Avanti platform. The patches move memory barriers after a write before the write. The result is that if there's iowrite followed by ioread, there is no barrier between them. The Alpha architecture allows reordering of the accesses to the I/O space, and the missing barrier between write and read causes hang with serial port and real time clock. This patch makes barriers confiorm to the specification. 1. We add mb() before readX_relaxed and writeX_relaxed - memory-barriers.txt claims that these functions must be ordered w.r.t. each other. Alpha doesn't order them, so we need an explicit barrier. 2. We add mb() before reads from the I/O space - so that if there's a write followed by a read, there should be a barrier between them. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Fixes: cd0e00c106 ("alpha: io: reorder barriers to guarantee writeX() and iowriteX() ordering") Fixes: 92d7223a74 ("alpha: io: reorder barriers to guarantee writeX() and iowriteX() ordering #2") Cc: stable@vger.kernel.org # v4.17+ Acked-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Reviewed-by: Maciej W. Rozycki <macro@linux-mips.org> Signed-off-by: Matt Turner <mattst88@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2020-06-22 09:05:28 +02:00
..
boot	kbuild: Rename HOSTCFLAGS to KBUILD_HOSTCFLAGS	2018-07-18 01:18:05 +09:00
include	alpha: fix memory barriers so that they conform to the specification	2020-06-22 09:05:28 +02:00
kernel	alpha: fix memory barriers so that they conform to the specification	2020-06-22 09:05:28 +02:00
lib	alpha: Remove custom dec_and_lock() implementation	2018-06-12 23:33:24 +02:00
math-emu	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
mm	alpha: fix page fault handling for r16-r18 targets	2019-02-20 10:25:47 +01:00
oprofile	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
defconfig	alpha: defconfig: Cleanup from old Kconfig options	2017-09-04 12:04:33 -07:00
Kconfig	kconfig: include kernel/Kconfig.preempt from init/Kconfig	2018-08-02 08:06:54 +09:00
Kconfig.debug	Kconfig: consolidate the "Kernel hacking" menu	2018-08-02 08:06:48 +09:00
Makefile	kbuild: add machine size to CHECKFLAGS	2018-06-01 11:36:58 +09:00