From: Mauri de Souza Meneguzzo <mauri870@gmail.com>
Date: Tue, 17 Oct 2023 22:54:27 +0000 (+0000)
Subject: runtime/internal/atomic: add memory barrier for mips Cas on failure
X-Git-Tag: go1.22rc1~525
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=25ad137cf4f0823b877a19f36479dbde005bfa10;p=gostls13.git

runtime/internal/atomic: add memory barrier for mips Cas on failure

Add a memory barrier on the failure case of the
compare-and-swap for mips, this avoids potential
race conditions.

For #63506

Change-Id: I3df1479d1438ba72aa72567eb3dea76ff745e98d
GitHub-Last-Rev: 2101b9fd446f28f856986b27d20f92cd4a1f4fef
GitHub-Pull-Request: golang/go#63604
Reviewed-on: https://go-review.googlesource.com/c/go/+/536116
Auto-Submit: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Keith Randall <khr@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
---

diff --git a/src/runtime/internal/atomic/atomic_mipsx.go b/src/runtime/internal/atomic/atomic_mipsx.go
index 5dd15a0b02..e3dcde1bde 100644
--- a/src/runtime/internal/atomic/atomic_mipsx.go
+++ b/src/runtime/internal/atomic/atomic_mipsx.go
@@ -48,11 +48,6 @@ func unlock() {
 	spinUnlock(&lock.state)
 }
 
-//go:nosplit
-func unlockNoFence() {
-	lock.state = 0
-}
-
 //go:nosplit
 func Xadd64(addr *uint64, delta int64) (new uint64) {
 	lockAndCheck(addr)
@@ -85,7 +80,7 @@ func Cas64(addr *uint64, old, new uint64) (swapped bool) {
 		return true
 	}
 
-	unlockNoFence()
+	unlock()
 	return false
 }
 
diff --git a/src/runtime/internal/atomic/atomic_mipsx.s b/src/runtime/internal/atomic/atomic_mipsx.s
index 390e9ce7ac..8f5fc53cb7 100644
--- a/src/runtime/internal/atomic/atomic_mipsx.s
+++ b/src/runtime/internal/atomic/atomic_mipsx.s
@@ -28,6 +28,7 @@ try_cas:
 	MOVB	R3, ret+12(FP)
 	RET
 cas_fail:
+	SYNC
 	MOVB	R0, ret+12(FP)
 	RET