Merge pull request #1 from google/master

catch up

6 files changed, 19 insertions, 210 deletions

diff --git a/pkg/atomicbitops/BUILD b/pkg/atomicbitops/BUILD
index 36beaade9..1a30f6967 100644
--- a/pkg/atomicbitops/BUILD
+++ b/pkg/atomicbitops/BUILD
@@ -1,23 +1,22 @@
-load("//tools/go_stateify:defs.bzl", "go_library")
-load("@io_bazel_rules_go//go:def.bzl", "go_test")
+load("//tools:defs.bzl", "go_library", "go_test")
 
 package(licenses = ["notice"])
 
 go_library(
     name = "atomicbitops",
     srcs = [
-        "atomic_bitops.go",
-        "atomic_bitops_amd64.s",
-        "atomic_bitops_arm64.s",
-        "atomic_bitops_common.go",
+        "atomicbitops.go",
+        "atomicbitops_amd64.s",
+        "atomicbitops_arm64.s",
+        "atomicbitops_noasm.go",
     ],
-    importpath = "gvisor.dev/gvisor/pkg/atomicbitops",
     visibility = ["//:sandbox"],
 )
 
 go_test(
     name = "atomicbitops_test",
     size = "small",
-    srcs = ["atomic_bitops_test.go"],
-    embed = [":atomicbitops"],
+    srcs = ["atomicbitops_test.go"],
+    library = ":atomicbitops",
+    deps = ["//pkg/sync"],
 )
diff --git a/pkg/atomicbitops/atomic_bitops.go b/pkg/atomicbitops/atomicbitops.go
index fcc41a9ea..1be081719 100644
--- a/pkg/atomicbitops/atomic_bitops.go
+++ b/pkg/atomicbitops/atomicbitops.go
@@ -14,47 +14,34 @@
 
 // +build amd64 arm64
 
-// Package atomicbitops provides basic bitwise operations in an atomic way.
-// The implementation on amd64 leverages the LOCK prefix directly instead of
-// relying on the generic cas primitives, and the arm64 leverages the LDAXR
-// and STLXR pair primitives.
+// Package atomicbitops provides extensions to the sync/atomic package.
 //
-// WARNING: the bitwise ops provided in this package doesn't imply any memory
-// ordering. Using them to construct locks must employ proper memory barriers.
+// All read-modify-write operations implemented by this package have
+// acquire-release memory ordering (like sync/atomic).
 package atomicbitops
 
-// AndUint32 atomically applies bitwise and operation to *addr with val.
+// AndUint32 atomically applies bitwise AND operation to *addr with val.
 func AndUint32(addr *uint32, val uint32)
 
-// OrUint32 atomically applies bitwise or operation to *addr with val.
+// OrUint32 atomically applies bitwise OR operation to *addr with val.
 func OrUint32(addr *uint32, val uint32)
 
-// XorUint32 atomically applies bitwise xor operation to *addr with val.
+// XorUint32 atomically applies bitwise XOR operation to *addr with val.
 func XorUint32(addr *uint32, val uint32)
 
 // CompareAndSwapUint32 is like sync/atomic.CompareAndSwapUint32, but returns
 // the value previously stored at addr.
 func CompareAndSwapUint32(addr *uint32, old, new uint32) uint32
 
-// AndUint64 atomically applies bitwise and operation to *addr with val.
+// AndUint64 atomically applies bitwise AND operation to *addr with val.
 func AndUint64(addr *uint64, val uint64)
 
-// OrUint64 atomically applies bitwise or operation to *addr with val.
+// OrUint64 atomically applies bitwise OR operation to *addr with val.
 func OrUint64(addr *uint64, val uint64)
 
-// XorUint64 atomically applies bitwise xor operation to *addr with val.
+// XorUint64 atomically applies bitwise XOR operation to *addr with val.
 func XorUint64(addr *uint64, val uint64)
 
 // CompareAndSwapUint64 is like sync/atomic.CompareAndSwapUint64, but returns
 // the value previously stored at addr.
 func CompareAndSwapUint64(addr *uint64, old, new uint64) uint64
-
-// IncUnlessZeroInt32 increments the value stored at the given address and
-// returns true; unless the value stored in the pointer is zero, in which case
-// it is left unmodified and false is returned.
-func IncUnlessZeroInt32(addr *int32) bool
-
-// DecUnlessOneInt32 decrements the value stored at the given address and
-// returns true; unless the value stored in the pointer is 1, in which case it
-// is left unmodified and false is returned.
-func DecUnlessOneInt32(addr *int32) bool
diff --git a/pkg/atomicbitops/atomic_bitops_amd64.s b/pkg/atomicbitops/atomicbitops_amd64.s
index db0972001..54c887ee5 100644
--- a/pkg/atomicbitops/atomic_bitops_amd64.s
+++ b/pkg/atomicbitops/atomicbitops_amd64.s
@@ -75,41 +75,3 @@ TEXT ·CompareAndSwapUint64(SB),$0-32
   CMPXCHGQ DX, 0(DI)
   MOVQ  AX, ret+24(FP)
   RET
-
-TEXT ·IncUnlessZeroInt32(SB),NOSPLIT,$0-9
-  MOVQ     addr+0(FP), DI
-  MOVL     0(DI), AX
-
-retry:
-  TESTL    AX, AX
-  JZ       fail
-  LEAL     1(AX), DX
-  LOCK
-  CMPXCHGL DX, 0(DI)
-  JNZ      retry
-
-  SETEQ    ret+8(FP)
-  RET
-
-fail:
-  MOVB     AX, ret+8(FP)
-  RET
-
-TEXT ·DecUnlessOneInt32(SB),NOSPLIT,$0-9
-  MOVQ     addr+0(FP), DI
-  MOVL     0(DI), AX
-
-retry:
-  LEAL     -1(AX), DX
-  TESTL    DX, DX
-  JZ       fail
-  LOCK
-  CMPXCHGL DX, 0(DI)
-  JNZ      retry
-
-  SETEQ    ret+8(FP)
-  RET
-
-fail:
-  MOVB     DX, ret+8(FP)
-  RET
diff --git a/pkg/atomicbitops/atomic_bitops_arm64.s b/pkg/atomicbitops/atomicbitops_arm64.s
index 97f8808c1..5c780851b 100644
--- a/pkg/atomicbitops/atomic_bitops_arm64.s
+++ b/pkg/atomicbitops/atomicbitops_arm64.s
@@ -50,7 +50,6 @@ TEXT ·CompareAndSwapUint32(SB),$0-20
   MOVD addr+0(FP), R0
   MOVW old+8(FP), R1
   MOVW new+12(FP), R2
-
 again:
   LDAXRW (R0), R3
   CMPW R1, R3
@@ -95,7 +94,6 @@ TEXT ·CompareAndSwapUint64(SB),$0-32
   MOVD addr+0(FP), R0
   MOVD old+8(FP), R1
   MOVD new+16(FP), R2
-
 again:
   LDAXR (R0), R3
   CMP R1, R3
@@ -105,35 +103,3 @@ again:
 done:
   MOVD R3, prev+24(FP)
   RET
-
-TEXT ·IncUnlessZeroInt32(SB),NOSPLIT,$0-9
-  MOVD addr+0(FP), R0
-
-again:
-  LDAXRW (R0), R1
-  CBZ R1, fail
-  ADDW $1, R1
-  STLXRW R1, (R0), R2
-  CBNZ R2, again
-  MOVW $1, R2
-  MOVB R2, ret+8(FP)
-  RET
-fail:
-  MOVB ZR, ret+8(FP)
-  RET
-
-TEXT ·DecUnlessOneInt32(SB),NOSPLIT,$0-9
-  MOVD addr+0(FP), R0
-
-again:
-  LDAXRW (R0), R1
-  SUBSW $1, R1, R1
-  BEQ fail
-  STLXRW R1, (R0), R2
-  CBNZ R2, again
-  MOVW $1, R2
-  MOVB R2, ret+8(FP)
-  RET
-fail:
-  MOVB ZR, ret+8(FP)
-  RET
diff --git a/pkg/atomicbitops/atomic_bitops_common.go b/pkg/atomicbitops/atomicbitops_noasm.go
index 85163ad62..3b2898256 100644
--- a/pkg/atomicbitops/atomic_bitops_common.go
+++ b/pkg/atomicbitops/atomicbitops_noasm.go
@@ -20,7 +20,6 @@ import (
 	"sync/atomic"
 )
 
-// AndUint32 atomically applies bitwise and operation to *addr with val.
 func AndUint32(addr *uint32, val uint32) {
 	for {
 		o := atomic.LoadUint32(addr)
@@ -31,7 +30,6 @@ func AndUint32(addr *uint32, val uint32) {
 	}
 }
 
-// OrUint32 atomically applies bitwise or operation to *addr with val.
 func OrUint32(addr *uint32, val uint32) {
 	for {
 		o := atomic.LoadUint32(addr)
@@ -42,7 +40,6 @@ func OrUint32(addr *uint32, val uint32) {
 	}
 }
 
-// XorUint32 atomically applies bitwise xor operation to *addr with val.
 func XorUint32(addr *uint32, val uint32) {
 	for {
 		o := atomic.LoadUint32(addr)
@@ -53,8 +50,6 @@ func XorUint32(addr *uint32, val uint32) {
 	}
 }
 
-// CompareAndSwapUint32 is like sync/atomic.CompareAndSwapUint32, but returns
-// the value previously stored at addr.
 func CompareAndSwapUint32(addr *uint32, old, new uint32) (prev uint32) {
 	for {
 		prev = atomic.LoadUint32(addr)
@@ -67,7 +62,6 @@ func CompareAndSwapUint32(addr *uint32, old, new uint32) (prev uint32) {
 	}
 }
 
-// AndUint64 atomically applies bitwise and operation to *addr with val.
 func AndUint64(addr *uint64, val uint64) {
 	for {
 		o := atomic.LoadUint64(addr)
@@ -78,7 +72,6 @@ func AndUint64(addr *uint64, val uint64) {
 	}
 }
 
-// OrUint64 atomically applies bitwise or operation to *addr with val.
 func OrUint64(addr *uint64, val uint64) {
 	for {
 		o := atomic.LoadUint64(addr)
@@ -89,7 +82,6 @@ func OrUint64(addr *uint64, val uint64) {
 	}
 }
 
-// XorUint64 atomically applies bitwise xor operation to *addr with val.
 func XorUint64(addr *uint64, val uint64) {
 	for {
 		o := atomic.LoadUint64(addr)
@@ -100,8 +92,6 @@ func XorUint64(addr *uint64, val uint64) {
 	}
 }
 
-// CompareAndSwapUint64 is like sync/atomic.CompareAndSwapUint64, but returns
-// the value previously stored at addr.
 func CompareAndSwapUint64(addr *uint64, old, new uint64) (prev uint64) {
 	for {
 		prev = atomic.LoadUint64(addr)
@@ -113,35 +103,3 @@ func CompareAndSwapUint64(addr *uint64, old, new uint64) (prev uint64) {
 		}
 	}
 }
-
-// IncUnlessZeroInt32 increments the value stored at the given address and
-// returns true; unless the value stored in the pointer is zero, in which case
-// it is left unmodified and false is returned.
-func IncUnlessZeroInt32(addr *int32) bool {
-	for {
-		v := atomic.LoadInt32(addr)
-		if v == 0 {
-			return false
-		}
-
-		if atomic.CompareAndSwapInt32(addr, v, v+1) {
-			return true
-		}
-	}
-}
-
-// DecUnlessOneInt32 decrements the value stored at the given address and
-// returns true; unless the value stored in the pointer is 1, in which case it
-// is left unmodified and false is returned.
-func DecUnlessOneInt32(addr *int32) bool {
-	for {
-		v := atomic.LoadInt32(addr)
-		if v == 1 {
-			return false
-		}
-
-		if atomic.CompareAndSwapInt32(addr, v, v-1) {
-			return true
-		}
-	}
-}
diff --git a/pkg/atomicbitops/atomic_bitops_test.go b/pkg/atomicbitops/atomicbitops_test.go
index 965e9be79..73af71bb4 100644
--- a/pkg/atomicbitops/atomic_bitops_test.go
+++ b/pkg/atomicbitops/atomicbitops_test.go
@@ -16,8 +16,9 @@ package atomicbitops
 
 import (
 	"runtime"
-	"sync"
 	"testing"
+
+	"gvisor.dev/gvisor/pkg/sync"
 )
 
 const iterations = 100
@@ -195,67 +196,3 @@ func TestCompareAndSwapUint64(t *testing.T) {
 		}
 	}
 }
-
-func TestIncUnlessZeroInt32(t *testing.T) {
-	for _, test := range []struct {
-		initial int32
-		final   int32
-		ret     bool
-	}{
-		{
-			initial: 0,
-			final:   0,
-			ret:     false,
-		},
-		{
-			initial: 1,
-			final:   2,
-			ret:     true,
-		},
-		{
-			initial: 2,
-			final:   3,
-			ret:     true,
-		},
-	} {
-		val := test.initial
-		if got, want := IncUnlessZeroInt32(&val), test.ret; got != want {
-			t.Errorf("For initial value of %d: incorrect return value: got %v, wanted %v", test.initial, got, want)
-		}
-		if got, want := val, test.final; got != want {
-			t.Errorf("For initial value of %d: incorrect final value: got %d, wanted %d", test.initial, got, want)
-		}
-	}
-}
-
-func TestDecUnlessOneInt32(t *testing.T) {
-	for _, test := range []struct {
-		initial int32
-		final   int32
-		ret     bool
-	}{
-		{
-			initial: 0,
-			final:   -1,
-			ret:     true,
-		},
-		{
-			initial: 1,
-			final:   1,
-			ret:     false,
-		},
-		{
-			initial: 2,
-			final:   1,
-			ret:     true,
-		},
-	} {
-		val := test.initial
-		if got, want := DecUnlessOneInt32(&val), test.ret; got != want {
-			t.Errorf("For initial value of %d: incorrect return value: got %v, wanted %v", test.initial, got, want)
-		}
-		if got, want := val, test.final; got != want {
-			t.Errorf("For initial value of %d: incorrect final value: got %d, wanted %d", test.initial, got, want)
-		}
-	}
-}