[PATCH 5.8 444/464] Revert "parisc: Revert "Release spinlocks using ordered store""

From: Greg Kroah-Hartman
Date: Mon Aug 17 2020 - 15:16:25 EST


From: Helge Deller <deller@xxxxxx>

commit 157e9afcc4fa25068b0e8743bc254a9b56010e13 upstream.

This reverts commit 86d4d068df573a8c2105554624796c086d6bec3d.

Signed-off-by: Helge Deller <deller@xxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v5.0+
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
arch/parisc/include/asm/spinlock.h | 4 ++--
arch/parisc/kernel/syscall.S | 12 ++++--------
2 files changed, 6 insertions(+), 10 deletions(-)

--- a/arch/parisc/include/asm/spinlock.h
+++ b/arch/parisc/include/asm/spinlock.h
@@ -37,8 +37,8 @@ static inline void arch_spin_unlock(arch
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)
--- a/arch/parisc/kernel/syscall.S
+++ b/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