Revert "parisc: Revert "Release spinlocks using ordered store""

This reverts commit 86d4d068df.

Signed-off-by: Helge Deller <deller@gmx.de>
Cc: <stable@vger.kernel.org> # v5.0+

arch/parisc/include/asm/spinlock.h

@@ -37,8 +37,8 @@ static inline void arch_spin_unlock(arch_spinlock_t *x)
 	volatile unsigned int *a;
 
 	a = __ldcw_align(x);
-	mb();
-	*a = 1;
+	/* Release with ordered store. */
+	__asm__ __volatile__("stw,ma %0,0(%1)" : : "r"(1), "r"(a) : "memory");
 }
 
 static inline int arch_spin_trylock(arch_spinlock_t *x)

arch/parisc/kernel/syscall.S

@@ -640,8 +640,7 @@ cas_action:
 	sub,<>	%r28, %r25, %r0
 2:	stw	%r24, 0(%r26)
 	/* Free lock */
-	sync
-	stw	%r20, 0(%sr2,%r20)
+	stw,ma	%r20, 0(%sr2,%r20)
 #if ENABLE_LWS_DEBUG
 	/* Clear thread register indicator */
 	stw	%r0, 4(%sr2,%r20)
@@ -655,8 +654,7 @@ cas_action:
 3:		
 	/* Error occurred on load or store */
 	/* Free lock */
-	sync
-	stw	%r20, 0(%sr2,%r20)
+	stw,ma	%r20, 0(%sr2,%r20)
 #if ENABLE_LWS_DEBUG
 	stw	%r0, 4(%sr2,%r20)
 #endif
@@ -857,8 +855,7 @@ cas2_action:
 
 cas2_end:
 	/* Free lock */
-	sync
-	stw	%r20, 0(%sr2,%r20)
+	stw,ma	%r20, 0(%sr2,%r20)
 	/* Enable interrupts */
 	ssm	PSW_SM_I, %r0
 	/* Return to userspace, set no error */
@@ -868,8 +865,7 @@ cas2_end:
 22:
 	/* Error occurred on load or store */
 	/* Free lock */
-	sync
-	stw	%r20, 0(%sr2,%r20)
+	stw,ma	%r20, 0(%sr2,%r20)
 	ssm	PSW_SM_I, %r0
 	ldo	1(%r0),%r28
 	b	lws_exit