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authorAndreas Larsson <andreas@gaisler.com>2014-11-05 15:52:08 +0100
committerDavid S. Miller <davem@davemloft.net>2014-11-07 12:51:44 -0800
commit1a17fdc4f4ed06b63fac1937470378a5441a663a (patch)
tree1590a724b9a40458ba1a990ceb41fc51839196fc /arch/sparc/lib
parentab5c780913bca0a5763ca05dd5c2cb5cb08ccb26 (diff)
downloadlinux-1a17fdc4f4ed06b63fac1937470378a5441a663a.tar.gz
sparc32: Implement xchg and atomic_xchg using ATOMIC_HASH locks
Atomicity between xchg and cmpxchg cannot be guaranteed when xchg is implemented with a swap and cmpxchg is implemented with locks. Without this, e.g. mcs_spin_lock and mcs_spin_unlock are broken. Signed-off-by: Andreas Larsson <andreas@gaisler.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/sparc/lib')
-rw-r--r--arch/sparc/lib/atomic32.c27
1 files changed, 27 insertions, 0 deletions
diff --git a/arch/sparc/lib/atomic32.c b/arch/sparc/lib/atomic32.c
index a7c418ac26af..71cd65ab200c 100644
--- a/arch/sparc/lib/atomic32.c
+++ b/arch/sparc/lib/atomic32.c
@@ -45,6 +45,19 @@ ATOMIC_OP(add, +=)
#undef ATOMIC_OP
+int atomic_xchg(atomic_t *v, int new)
+{
+ int ret;
+ unsigned long flags;
+
+ spin_lock_irqsave(ATOMIC_HASH(v), flags);
+ ret = v->counter;
+ v->counter = new;
+ spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
+ return ret;
+}
+EXPORT_SYMBOL(atomic_xchg);
+
int atomic_cmpxchg(atomic_t *v, int old, int new)
{
int ret;
@@ -137,3 +150,17 @@ unsigned long __cmpxchg_u32(volatile u32 *ptr, u32 old, u32 new)
return (unsigned long)prev;
}
EXPORT_SYMBOL(__cmpxchg_u32);
+
+unsigned long __xchg_u32(volatile u32 *ptr, u32 new)
+{
+ unsigned long flags;
+ u32 prev;
+
+ spin_lock_irqsave(ATOMIC_HASH(ptr), flags);
+ prev = *ptr;
+ *ptr = new;
+ spin_unlock_irqrestore(ATOMIC_HASH(ptr), flags);
+
+ return (unsigned long)prev;
+}
+EXPORT_SYMBOL(__xchg_u32);