tools/syz-repro: order Loop() and vmPool.Close()

There used to be no strict ordering between cancelling the loop context
and the actual moment the Loop() method exits. Now that we assert that
all instances are freed in vmPool.Close(), we need to wait until Loop()
finishes before closing the VM pool.

Restructure the main() method to ensure this order.

1 files changed, 37 insertions, 35 deletions

diff --git a/tools/syz-repro/repro.go b/tools/syz-repro/repro.go
index c7526af3d..220170599 100644
--- a/tools/syz-repro/repro.go
+++ b/tools/syz-repro/repro.go
@@ -62,45 +62,47 @@ func main() {
 	}
 	pool := vm.NewDispatcher(vmPool, nil)
 	pool.ReserveForRun(count)
-	ctx, done := context.WithCancel(context.Background())
-	go pool.Loop(ctx)
-	defer done()
 
-	res, stats, err := repro.Run(data, cfg, flatrpc.AllFeatures, reporter, pool)
-	if err != nil {
-		log.Logf(0, "reproduction failed: %v", err)
-	}
-	if stats != nil {
-		fmt.Printf("extracting prog: %v\n", stats.ExtractProgTime)
-		fmt.Printf("minimizing prog: %v\n", stats.MinimizeProgTime)
-		fmt.Printf("simplifying prog options: %v\n", stats.SimplifyProgTime)
-		fmt.Printf("extracting C: %v\n", stats.ExtractCTime)
-		fmt.Printf("simplifying C: %v\n", stats.SimplifyCTime)
-	}
-	if res == nil {
-		return
-	}
+	ctx, done := context.WithCancel(context.Background())
+	go func() {
+		defer done()
 
-	fmt.Printf("opts: %+v crepro: %v\n\n", res.Opts, res.CRepro)
+		res, stats, err := repro.Run(data, cfg, flatrpc.AllFeatures, reporter, pool)
+		if err != nil {
+			log.Logf(0, "reproduction failed: %v", err)
+		}
+		if stats != nil {
+			fmt.Printf("extracting prog: %v\n", stats.ExtractProgTime)
+			fmt.Printf("minimizing prog: %v\n", stats.MinimizeProgTime)
+			fmt.Printf("simplifying prog options: %v\n", stats.SimplifyProgTime)
+			fmt.Printf("extracting C: %v\n", stats.ExtractCTime)
+			fmt.Printf("simplifying C: %v\n", stats.SimplifyCTime)
+		}
+		if res == nil {
+			return
+		}
 
-	progSerialized := res.Prog.Serialize()
-	fmt.Printf("%s\n", progSerialized)
-	if err = osutil.WriteFile(*flagOutput, progSerialized); err == nil {
-		fmt.Printf("program saved to %s\n", *flagOutput)
-	} else {
-		log.Logf(0, "failed to write prog to file: %v", err)
-	}
+		fmt.Printf("opts: %+v crepro: %v\n\n", res.Opts, res.CRepro)
+		progSerialized := res.Prog.Serialize()
+		fmt.Printf("%s\n", progSerialized)
+		if err = osutil.WriteFile(*flagOutput, progSerialized); err == nil {
+			fmt.Printf("program saved to %s\n", *flagOutput)
+		} else {
+			log.Logf(0, "failed to write prog to file: %v", err)
+		}
 
-	if res.Report != nil && *flagTitle != "" {
-		recordTitle(res, *flagTitle)
-	}
-	if res.CRepro {
-		recordCRepro(res, *flagCRepro)
-	}
-	if *flagStrace != "" {
-		result := repro.RunStrace(res, cfg, reporter, pool)
-		recordStraceResult(result, *flagStrace)
-	}
+		if res.Report != nil && *flagTitle != "" {
+			recordTitle(res, *flagTitle)
+		}
+		if res.CRepro {
+			recordCRepro(res, *flagCRepro)
+		}
+		if *flagStrace != "" {
+			result := repro.RunStrace(res, cfg, reporter, pool)
+			recordStraceResult(result, *flagStrace)
+		}
+	}()
+	pool.Loop(ctx)
 }
 
 func recordTitle(res *repro.Result, fileName string) {