Merge remote-tracking branch 'lsk/v3.10/topic/gator' into linux-linaro-lsk

[firefly-linux-kernel-4.4.55.git] / arch / arm / include / asm / spinlock.h

diff --git a/arch/arm/include/asm/spinlock.h b/arch/arm/include/asm/spinlock.h
index f8b8965666e9b14842786742f48ccdef49000802..b07c09e5a0ac86c6ddd5f7bc9ba25425c784e147 100644 (file)
--- a/arch/arm/include/asm/spinlock.h
+++ b/arch/arm/include/asm/spinlock.h
@@ -107,7 +107,7 @@ static inline int arch_spin_trylock(arch_spinlock_t *lock)
                "       subs    %1, %0, %0, ror #16\n"
                "       addeq   %0, %0, %4\n"
                "       strexeq %2, %0, [%3]"
-               : "=&r" (slock), "=&r" (contended), "=r" (res)
+               : "=&r" (slock), "=&r" (contended), "=&r" (res)
                : "r" (&lock->slock), "I" (1 << TICKET_SHIFT)
                : "cc");
        } while (res);
@@ -168,17 +168,20 @@ static inline void arch_write_lock(arch_rwlock_t *rw)
 
 static inline int arch_write_trylock(arch_rwlock_t *rw)
 {
-       unsigned long tmp;
+       unsigned long contended, res;
 
-       __asm__ __volatile__(
-"      ldrex   %0, [%1]\n"
-"      teq     %0, #0\n"
-"      strexeq %0, %2, [%1]"
-       : "=&r" (tmp)
-       : "r" (&rw->lock), "r" (0x80000000)
-       : "cc");
+       do {
+               __asm__ __volatile__(
+               "       ldrex   %0, [%2]\n"
+               "       mov     %1, #0\n"
+               "       teq     %0, #0\n"
+               "       strexeq %1, %3, [%2]"
+               : "=&r" (contended), "=&r" (res)
+               : "r" (&rw->lock), "r" (0x80000000)
+               : "cc");
+       } while (res);
 
-       if (tmp == 0) {
+       if (!contended) {
                smp_mb();
                return 1;
        } else {
@@ -254,18 +257,26 @@ static inline void arch_read_unlock(arch_rwlock_t *rw)
 
 static inline int arch_read_trylock(arch_rwlock_t *rw)
 {
-       unsigned long tmp, tmp2 = 1;
+       unsigned long contended, res;
 
-       __asm__ __volatile__(
-"      ldrex   %0, [%2]\n"
-"      adds    %0, %0, #1\n"
-"      strexpl %1, %0, [%2]\n"
-       : "=&r" (tmp), "+r" (tmp2)
-       : "r" (&rw->lock)
-       : "cc");
+       do {
+               __asm__ __volatile__(
+               "       ldrex   %0, [%2]\n"
+               "       mov     %1, #0\n"
+               "       adds    %0, %0, #1\n"
+               "       strexpl %1, %0, [%2]"
+               : "=&r" (contended), "=&r" (res)
+               : "r" (&rw->lock)
+               : "cc");
+       } while (res);
 
-       smp_mb();
-       return tmp2 == 0;
+       /* If the lock is negative, then it is already held for write. */
+       if (contended < 0x80000000) {
+               smp_mb();
+               return 1;
+       } else {
+               return 0;
+       }
 }
 
 /* read_can_lock - would read_trylock() succeed? */