From: John David Anglin <dave.anglin@bell.net>
Date: Tue, 6 Nov 2018 11:00:01 +0000 (+0100)
Subject: parisc: Revert "Release spinlocks using ordered store"
X-Git-Tag: v4.20-rc3~28^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=86d4d068df573a8c2105554624796c086d6bec3d;p=thirdparty%2Fkernel%2Flinux.git

parisc: Revert "Release spinlocks using ordered store"

This reverts commit d27dfa13b9f77ae7e6ed09d70a0426ed26c1a8f9.

Unfortunately, this patch needs to be reverted.  We need the full sync
barrier and not the limited barrier provided by using an ordered store.
The sync ensures that all accesses and cache purge instructions that
follow the sync are performed after all such instructions prior the sync
instruction have completed executing.

The patch breaks the rwlock implementation in glibc.  This caused the
test-lock application in the libprelude testsuite to hang.  With the
change reverted, the test runs correctly and the libprelude package
builds successfully.

Signed-off-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
---

diff --git a/arch/parisc/include/asm/spinlock.h b/arch/parisc/include/asm/spinlock.h
index 16aec9ba2580a..8a63515f03bfe 100644
--- 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_spinlock_t *x)
 	volatile unsigned int *a;
 
 	a = __ldcw_align(x);
-	/* Release with ordered store. */
-	__asm__ __volatile__("stw,ma %0,0(%1)" : : "r"(1), "r"(a) : "memory");
+	mb();
+	*a = 1;
 }
 
 static inline int arch_spin_trylock(arch_spinlock_t *x)
diff --git a/arch/parisc/kernel/syscall.S b/arch/parisc/kernel/syscall.S
index 9505c317818df..a9bc90dc4ae75 100644
--- a/arch/parisc/kernel/syscall.S
+++ b/arch/parisc/kernel/syscall.S
@@ -640,7 +640,8 @@ cas_action:
 	sub,<>	%r28, %r25, %r0
 2:	stw	%r24, 0(%r26)
 	/* Free lock */
-	stw,ma	%r20, 0(%sr2,%r20)
+	sync
+	stw	%r20, 0(%sr2,%r20)
 #if ENABLE_LWS_DEBUG
 	/* Clear thread register indicator */
 	stw	%r0, 4(%sr2,%r20)
@@ -654,7 +655,8 @@ cas_action:
 3:		
 	/* Error occurred on load or store */
 	/* Free lock */
-	stw,ma	%r20, 0(%sr2,%r20)
+	sync
+	stw	%r20, 0(%sr2,%r20)
 #if ENABLE_LWS_DEBUG
 	stw	%r0, 4(%sr2,%r20)
 #endif
@@ -855,7 +857,8 @@ cas2_action:
 
 cas2_end:
 	/* Free lock */
-	stw,ma	%r20, 0(%sr2,%r20)
+	sync
+	stw	%r20, 0(%sr2,%r20)
 	/* Enable interrupts */
 	ssm	PSW_SM_I, %r0
 	/* Return to userspace, set no error */
@@ -865,7 +868,8 @@ cas2_end:
 22:
 	/* Error occurred on load or store */
 	/* Free lock */
-	stw,ma	%r20, 0(%sr2,%r20)
+	sync
+	stw	%r20, 0(%sr2,%r20)
 	ssm	PSW_SM_I, %r0
 	ldo	1(%r0),%r28
 	b	lws_exit