Author: kib
Date: Wed Aug 12 09:43:12 2015
New Revision: 286657
URL: https://svnweb.freebsd.org/changeset/base/286657
Log:
AP should load aps_ready with acquire semantic to see BSP updates to
the SMP structures, synchronized with the load by release store in
release_aps().
The change is formal, x86 strong memory model implicitely provided
the guarantees.
Discussed with: bde
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Modified:
head/sys/amd64/amd64/mp_machdep.c
head/sys/i386/i386/mp_machdep.c
Modified: head/sys/amd64/amd64/mp_machdep.c
==============================================================================
--- head/sys/amd64/amd64/mp_machdep.c Wed Aug 12 08:41:48 2015
(r286656)
+++ head/sys/amd64/amd64/mp_machdep.c Wed Aug 12 09:43:12 2015
(r286657)
@@ -282,7 +282,7 @@ init_secondary(void)
mp_naps++;
/* Spin until the BSP releases the AP's. */
- while (!aps_ready)
+ while (atomic_load_acq_int(&aps_ready) == 0)
ia32_pause();
init_secondary_tail();
Modified: head/sys/i386/i386/mp_machdep.c
==============================================================================
--- head/sys/i386/i386/mp_machdep.c Wed Aug 12 08:41:48 2015
(r286656)
+++ head/sys/i386/i386/mp_machdep.c Wed Aug 12 09:43:12 2015
(r286657)
@@ -291,7 +291,7 @@ init_secondary(void)
CHECK_WRITE(0x39, 6);
/* Spin until the BSP releases the AP's. */
- while (!aps_ready)
+ while (atomic_load_acq_int(&aps_ready) == 0)
ia32_pause();
/* BSP may have changed PTD while we were waiting */
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