Cleanup in signal.c and related tests

Add comments, add assert for edge case around signal registration, and
make consistent *always* using atomic get/set for memory shared
between the signal handler and the threads.

2 files changed, 5 insertions, 0 deletions

diff --git a/mcs/class/Mono.Posix/Mono.Unix/UnixSignal.cs b/mcs/class/Mono.Posix/Mono.Unix/UnixSignal.cs
index b71743f9102..6c441e528eb 100644
--- a/mcs/class/Mono.Posix/Mono.Unix/UnixSignal.cs
+++ b/mcs/class/Mono.Posix/Mono.Unix/UnixSignal.cs
@@ -145,6 +145,8 @@ namespace Mono.Unix {
 			set {Interlocked.Exchange (ref Info->count, value);}
 		}
 
+		// signum, count, write_fd, pipecnt, and pipelock are read from a signal handler thread
+		// count and pipelock are both read and written from the signal handler thread
 		[Map]
 		struct SignalInfo {
 			public int signum, count, read_fd, write_fd, pipecnt, pipelock, have_handler;
diff --git a/mcs/class/Mono.Posix/Test/Mono.Unix/UnixSignalTest.cs b/mcs/class/Mono.Posix/Test/Mono.Unix/UnixSignalTest.cs
index 14613104d9b..d621ad51d45 100644
--- a/mcs/class/Mono.Posix/Test/Mono.Unix/UnixSignalTest.cs
+++ b/mcs/class/Mono.Posix/Test/Mono.Unix/UnixSignalTest.cs
@@ -456,6 +456,7 @@ namespace MonoTests.Mono.Unix {
 				s.Close ();
 		}
 
+		// Create thread that issues many signals from a set of harmless signals
 		static Thread CreateRaiseStormThread (int max)
 		{
 			return new Thread (delegate () {
@@ -486,6 +487,7 @@ namespace MonoTests.Mono.Unix {
 			CloseSignals (usignals);
 		}
 
+		// Create thread that repeatedly registers then unregisters signal handlers
 		static Thread CreateSignalCreatorThread ()
 		{
 			return new Thread (delegate () {
@@ -523,6 +525,7 @@ namespace MonoTests.Mono.Unix {
 			CloseSignals (usignals);
 		}
 
+		// Create thread that blocks until at least one of the given signals is received
 		static Thread CreateWaitAnyThread (params UnixSignal[] usignals)
 		{
 			return new Thread (delegate () {