systrap: Rename fpState to fastpath.

FPState is already used in ThreadContexts. It's better to rename this
global to something more descriptive.

PiperOrigin-RevId: 597920631

pkg/sentry/platform/systrap/context_queue.go

@@ -100,7 +100,7 @@ func (q *contextQueue) queuedContexts() uint32 {
 func (q *contextQueue) add(ctx *sharedContext) {
 	ctx.startWaitingTS = cputicks()
 
-	if fpState.stubFastPath() {
+	if fastpath.stubFastPath() {
 		q.enableFastPath()
 	} else {
 		q.disableFastPath()
@@ -119,7 +119,7 @@ func (q *contextQueue) add(ctx *sharedContext) {
 	atomic.StoreUint64(&q.ringbuffer[next], v)
 
 	if atomic.SwapUint32(&q.usedFastPath, 0) != 0 {
-		fpState.usedStubFastPath.Store(true)
+		fastpath.usedStubFastPath.Store(true)
 	}
 }
 

pkg/sentry/platform/systrap/metrics.go

@@ -241,7 +241,7 @@ type fastPathState struct {
 }
 
 var (
-	fpState = fastPathState{
+	fastpath = fastPathState{
 		stubFPBackoff:   fastPathBackoffMin,
 		sentryFPBackoff: fastPathBackoffMin,
 		curState:        sentryOffStubOff,
@@ -262,10 +262,10 @@ func controlFastPath() {
 	for {
 		time.Sleep(recordingPeriod)
 
-		fpState.curState(&fpState)
+		fastpath.curState(&fastpath)
 		// Reset FP trackers.
-		fpState.usedStubFastPath.Store(false)
-		fpState.usedSentryFastPath.Store(false)
+		fastpath.usedStubFastPath.Store(false)
+		fastpath.usedSentryFastPath.Store(false)
 	}
 }
 

pkg/sentry/platform/systrap/shared_context.go

@@ -317,7 +317,7 @@ func (q *fastPathDispatcher) loop(target *sharedContext) {
 			break
 		}
 
-		slowPath = !fpState.sentryFastPath() || slowPath
+		slowPath = !fastpath.sentryFastPath() || slowPath
 		processed = 0
 		now := cputicks()
 		for ctx = q.list.Front(); ctx != nil; ctx = next {
@@ -349,7 +349,7 @@ func (q *fastPathDispatcher) loop(target *sharedContext) {
 			startedSpinning = now
 			firstTimeout = false
 		} else {
-			fpState.usedSentryFastPath.Store(true)
+			fastpath.usedSentryFastPath.Store(true)
 		}
 		// If dispatcher has been spinning for too long, send this
 		// dispatcher to sleep.

pkg/sentry/platform/systrap/subprocess.go

@@ -701,7 +701,7 @@ func (s *subprocess) incAwakeContexts() {
 	if nr > uint32(maxSysmsgThreads) {
 		return
 	}
-	fpState.nrMaxAwakeStubThreads.Add(1)
+	fastpath.nrMaxAwakeStubThreads.Add(1)
 }
 
 func (s *subprocess) decAwakeContexts() {
@@ -709,7 +709,7 @@ func (s *subprocess) decAwakeContexts() {
 	if nr >= uint32(maxSysmsgThreads) {
 		return
 	}
-	fpState.nrMaxAwakeStubThreads.Add(^uint32(0))
+	fastpath.nrMaxAwakeStubThreads.Add(^uint32(0))
 }
 
 // switchToApp is called from the main SwitchToApp entrypoint.