1 files changed, 3 insertions, 49 deletions
diff --git a/src/pkg/sync/mutex.go b/src/pkg/sync/mutex.go
index bf19f0dec..9ba628824 100644
--- a/src/pkg/sync/mutex.go
+++ b/src/pkg/sync/mutex.go
@@ -20,6 +20,9 @@ type Mutex struct {
 	sema	uint32;
 }
 
+// Add delta to *val, and return the new *val in a thread-safe way. If multiple
+// goroutines call xadd on the same val concurrently, the changes will be
+// serialized, and all the deltas will be added in an undefined order.
 func xadd(val *uint32, delta int32) (new uint32) {
 	for {
 		v := *val;
@@ -55,52 +58,3 @@ func (m *Mutex) Unlock() {
 	}
 	runtime.Semrelease(&m.sema);
 }
-
-// Stub implementation of r/w locks.
-// This satisfies the semantics but
-// is not terribly efficient.
-
-// The next comment goes in the BUGS section of the document,
-// in its own paragraph, without the (rsc) tag.
-
-// BUG(rsc): RWMutex does not (yet) allow multiple readers;
-// instead it behaves as if RLock and RUnlock were Lock and Unlock.
-
-// An RWMutex is a reader/writer mutual exclusion lock.
-// The lock can be held by an arbitrary number of readers
-// or a single writer.
-// RWMutexes can be created as part of other
-// structures; the zero value for a RWMutex is
-// an unlocked mutex.
-type RWMutex struct {
-	m Mutex;
-}
-
-// RLock locks rw for reading.
-// If the lock is already locked for writing or there is a writer already waiting
-// to acquire the lock, RLock blocks until the writer has released the lock.
-func (rw *RWMutex) RLock()	{ rw.m.Lock() }
-
-// RUnlock undoes a single RLock call;
-// it does not affect other simultaneous readers.
-// It is a run-time error if rw is not locked for reading
-// on entry to RUnlock.
-func (rw *RWMutex) RUnlock()	{ rw.m.Unlock() }
-
-// Lock locks rw for writing.
-// If the lock is already locked for reading or writing,
-// Lock blocks until the lock is available.
-// To ensure that the lock eventually becomes available,
-// a blocked Lock call excludes new readers from acquiring
-// the lock.
-func (rw *RWMutex) Lock()	{ rw.m.Lock() }
-
-// Unlock unlocks rw for writing.
-// It is a run-time error if rw is not locked for writing
-// on entry to Unlock.
-//
-// Like for Mutexes,
-// a locked RWMutex is not associated with a particular goroutine.
-// It is allowed for one goroutine to RLock (Lock) an RWMutex and then
-// arrange for another goroutine to RUnlock (Unlock) it.
-func (rw *RWMutex) Unlock()	{ rw.m.Unlock() }