From: John Hodge <tpg@mutabah.net>
Date: Sun, 27 Feb 2011 14:37:54 +0000 (+0800)
Subject: Kernel - Some rational comments to select
X-Git-Tag: rel0.10~188
X-Git-Url: https://git.ucc.asn.au/?a=commitdiff_plain;h=d9aa13b78d35a9460c5ea1ab260ae3470a551607;p=tpg%2Facess2.git

Kernel - Some rational comments to select
---

diff --git a/Kernel/vfs/select.c b/Kernel/vfs/select.c
index 46d6f39f..3cb0af2f 100644
--- a/Kernel/vfs/select.c
+++ b/Kernel/vfs/select.c
@@ -58,6 +58,15 @@ int VFS_Select(int MaxHandle, fd_set *ReadHandles, fd_set *WriteHandles, fd_set
 	tVFS_SelectThread	thread_info;
 	 int	ret;
 	
+	Semaphore_Init(&thread_info.SleepHandle, 0, 0, "VFS_Select()", "");
+	
+	// Notes: The idea is to make sure we onlt enter wait (on the semaphore)
+	// if we are going to be woken up (either by an event at a later time,
+	// or by an event that happened while or before we were registering).
+	// Hence, register must happen _before_ we check the state flag
+	// (See VFS_int_Select_Register), that way either we pick up the flag,
+	// or the semaphore is incremeneted (or both, but never none)
+	
 	// Register with nodes
 	ret  = VFS_int_Select_Register(&thread_info, MaxHandle, ReadHandles, 0, IsKernel);
 	ret += VFS_int_Select_Register(&thread_info, MaxHandle, WriteHandles, 1, IsKernel);