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Diffstat (limited to 'arch/arm/include/asm/spinlock.h')
-rw-r--r--arch/arm/include/asm/spinlock.h36
1 files changed, 20 insertions, 16 deletions
diff --git a/arch/arm/include/asm/spinlock.h b/arch/arm/include/asm/spinlock.h
index 4f2c28060c9a..ef3c6072aa45 100644
--- a/arch/arm/include/asm/spinlock.h
+++ b/arch/arm/include/asm/spinlock.h
@@ -5,21 +5,13 @@
#error SMP not supported on pre-ARMv6 CPUs
#endif
-#include <asm/processor.h>
+#include <linux/prefetch.h>
/*
* sev and wfe are ARMv6K extensions. Uniprocessor ARMv6 may not have the K
* extensions, so when running on UP, we have to patch these instructions away.
*/
-#define ALT_SMP(smp, up) \
- "9998: " smp "\n" \
- " .pushsection \".alt.smp.init\", \"a\"\n" \
- " .long 9998b\n" \
- " " up "\n" \
- " .popsection\n"
-
#ifdef CONFIG_THUMB2_KERNEL
-#define SEV ALT_SMP("sev.w", "nop.w")
/*
* For Thumb-2, special care is needed to ensure that the conditional WFE
* instruction really does assemble to exactly 4 bytes (as required by
@@ -31,17 +23,18 @@
* the assembler won't change IT instructions which are explicitly present
* in the input.
*/
-#define WFE(cond) ALT_SMP( \
+#define WFE(cond) __ALT_SMP_ASM( \
"it " cond "\n\t" \
"wfe" cond ".n", \
\
"nop.w" \
)
#else
-#define SEV ALT_SMP("sev", "nop")
-#define WFE(cond) ALT_SMP("wfe" cond, "nop")
+#define WFE(cond) __ALT_SMP_ASM("wfe" cond, "nop")
#endif
+#define SEV __ALT_SMP_ASM(WASM(sev), WASM(nop))
+
static inline void dsb_sev(void)
{
#if __LINUX_ARM_ARCH__ >= 7
@@ -77,6 +70,7 @@ static inline void arch_spin_lock(arch_spinlock_t *lock)
u32 newval;
arch_spinlock_t lockval;
+ prefetchw(&lock->slock);
__asm__ __volatile__(
"1: ldrex %0, [%3]\n"
" add %1, %0, %4\n"
@@ -100,6 +94,7 @@ static inline int arch_spin_trylock(arch_spinlock_t *lock)
unsigned long contended, res;
u32 slock;
+ prefetchw(&lock->slock);
do {
__asm__ __volatile__(
" ldrex %0, [%3]\n"
@@ -127,10 +122,14 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock)
dsb_sev();
}
+static inline int arch_spin_value_unlocked(arch_spinlock_t lock)
+{
+ return lock.tickets.owner == lock.tickets.next;
+}
+
static inline int arch_spin_is_locked(arch_spinlock_t *lock)
{
- struct __raw_tickets tickets = ACCESS_ONCE(lock->tickets);
- return tickets.owner != tickets.next;
+ return !arch_spin_value_unlocked(ACCESS_ONCE(*lock));
}
static inline int arch_spin_is_contended(arch_spinlock_t *lock)
@@ -152,6 +151,7 @@ static inline void arch_write_lock(arch_rwlock_t *rw)
{
unsigned long tmp;
+ prefetchw(&rw->lock);
__asm__ __volatile__(
"1: ldrex %0, [%1]\n"
" teq %0, #0\n"
@@ -170,6 +170,7 @@ static inline int arch_write_trylock(arch_rwlock_t *rw)
{
unsigned long contended, res;
+ prefetchw(&rw->lock);
do {
__asm__ __volatile__(
" ldrex %0, [%2]\n"
@@ -203,7 +204,7 @@ static inline void arch_write_unlock(arch_rwlock_t *rw)
}
/* write_can_lock - would write_trylock() succeed? */
-#define arch_write_can_lock(x) ((x)->lock == 0)
+#define arch_write_can_lock(x) (ACCESS_ONCE((x)->lock) == 0)
/*
* Read locks are a bit more hairy:
@@ -221,6 +222,7 @@ static inline void arch_read_lock(arch_rwlock_t *rw)
{
unsigned long tmp, tmp2;
+ prefetchw(&rw->lock);
__asm__ __volatile__(
"1: ldrex %0, [%2]\n"
" adds %0, %0, #1\n"
@@ -241,6 +243,7 @@ static inline void arch_read_unlock(arch_rwlock_t *rw)
smp_mb();
+ prefetchw(&rw->lock);
__asm__ __volatile__(
"1: ldrex %0, [%2]\n"
" sub %0, %0, #1\n"
@@ -259,6 +262,7 @@ static inline int arch_read_trylock(arch_rwlock_t *rw)
{
unsigned long contended, res;
+ prefetchw(&rw->lock);
do {
__asm__ __volatile__(
" ldrex %0, [%2]\n"
@@ -280,7 +284,7 @@ static inline int arch_read_trylock(arch_rwlock_t *rw)
}
/* read_can_lock - would read_trylock() succeed? */
-#define arch_read_can_lock(x) ((x)->lock < 0x80000000)
+#define arch_read_can_lock(x) (ACCESS_ONCE((x)->lock) < 0x80000000)
#define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
#define arch_write_lock_flags(lock, flags) arch_write_lock(lock)