From 1760f1eb7ec485197bd3a8a9c13e4160bb740275 Mon Sep 17 00:00:00 2001
From: Christian Borntraeger <borntraeger@de.ibm.com>
Date: Sun, 7 Dec 2014 22:01:59 +0100
Subject: x86/xen/p2m: Replace ACCESS_ONCE with READ_ONCE
ACCESS_ONCE does not work reliably on non-scalar types. For
example gcc 4.6 and 4.7 might remove the volatile tag for such
accesses during the SRA (scalar replacement of aggregates) step
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145)
Change the p2m code to replace ACCESS_ONCE with READ_ONCE.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Acked-by: David Vrabel <david.vrabel@citrix.com>
---
arch/x86/xen/p2m.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
(limited to 'arch/x86')
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index edbc7a63fd73..cb7101692a75 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -554,7 +554,7 @@ static bool alloc_p2m(unsigned long pfn)
mid_mfn = NULL;
}
- p2m_pfn = pte_pfn(ACCESS_ONCE(*ptep));
+ p2m_pfn = pte_pfn(READ_ONCE(*ptep));
if (p2m_pfn == PFN_DOWN(__pa(p2m_identity)) ||
p2m_pfn == PFN_DOWN(__pa(p2m_missing))) {
/* p2m leaf page is missing */
--
cgit v1.2.3-70-g09d2
From bccec2a0a25206cb837e939adab94768a990ffa9 Mon Sep 17 00:00:00 2001
From: Christian Borntraeger <borntraeger@de.ibm.com>
Date: Tue, 6 Jan 2015 22:49:54 +0100
Subject: x86/spinlock: Leftover conversion ACCESS_ONCE->READ_ONCE
commit 78bff1c8684f ("x86/ticketlock: Fix spin_unlock_wait() livelock")
introduced two additional ACCESS_ONCE cases in x86 spinlock.h.
Lets change those as well.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
---
arch/x86/include/asm/spinlock.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
(limited to 'arch/x86')
diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h
index 625660f8a2fc..7050d864f520 100644
--- a/arch/x86/include/asm/spinlock.h
+++ b/arch/x86/include/asm/spinlock.h
@@ -183,10 +183,10 @@ static __always_inline void arch_spin_lock_flags(arch_spinlock_t *lock,
static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
{
- __ticket_t head = ACCESS_ONCE(lock->tickets.head);
+ __ticket_t head = READ_ONCE(lock->tickets.head);
for (;;) {
- struct __raw_tickets tmp = ACCESS_ONCE(lock->tickets);
+ struct __raw_tickets tmp = READ_ONCE(lock->tickets);
/*
* We need to check "unlocked" in a loop, tmp.head == head
* can be false positive because of overflow.
--
cgit v1.2.3-70-g09d2