code review 132960044: runtime: changes to g->atomicstatus (nee status) to sup...

src/pkg/runtime/proc.go

 // Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package runtime
 
 import "unsafe"
 
 // This is not mechanically generated
 // so be very careful and refer to runtime.h
 // for the definitive enum.
 const (
         gStatusidle = iota
         gStatusRunnable
         gStatusRunning
         gStatusSyscall
         gStatusWaiting
         gStatusMoribundUnused
         gStatusDead
-        gStatusScanidle
-        gStatusScanrunnable
-        gStatusScanrunning
-        gStatusScanenqueue
-        gStatusScansyscall
-        gStatusScanwaiting
+        gStatusEnqueue
         gStatusCopystack
+        gStatusScan         = 0x1000
+        gStatusScanRunnable = gStatusScan + gStatusRunnable
+        gStatusScanRunning  = gStatusScan + gStatusRunning
+        gStatusScanSyscall  = gStatusScan + gStatusSyscall
+        gStatusScanWaiting  = gStatusScan + gStatusWaiting
+        gStatusScanEnqueue  = gStatusScan + gStatusEnqueue
 )
 
 var parkunlock_c byte
 
 // Gosched yields the processor, allowing other goroutines to run.  It does not
 // suspend the current goroutine, so execution resumes automatically.
 func Gosched() {
         mcall(&gosched_m)
 }
 
 func readgStatus(gp *g) uint32 {
         //return atomic.LoadUint32(&gp.atomicstatus) // TODO: add bootstrap code to provide.
         return gp.atomicstatus

[dvyukov, 2014/08/27 13:16:03]

we have goatomicload function

[rlh, 2014/08/27 15:15:53]

There are (or were as of yesterday) some bootstrap issues. It is being worked
on. I'll change it over in the next CL.

 }
 
 // Puts the current goroutine into a waiting state and calls unlockf.
 // If unlockf returns false, the goroutine is resumed.
 func gopark(unlockf unsafe.Pointer, lock unsafe.Pointer, reason string) {
         mp := acquirem()
         gp := mp.curg
         status := readgStatus(gp)
-        if status != gStatusRunning && status != gStatusScanrunning {
+        if status != gStatusRunning && status != gStatusScanRunning {
                 gothrow("gopark: bad g status")
         }
         mp.waitlock = lock
         mp.waitunlockf = *(*func(*g, unsafe.Pointer) uint8)(unsafe.Pointer(&unlockf))
         gp.waitreason = reason
         releasem(mp)
         // can't do anything that might move the G between Ms here.
         mcall(&park_m)
 }
 
@@ skipping 30 matching lines @@
         }
         return new(sudog)
 }
 
 //go:nosplit
 func releaseSudog(s *sudog) {
         c := gomcache()
         s.next = c.sudogcache
         c.sudogcache = s
 }