From 62a21143be0010e6f9681394cfa9e93960169dcb Mon Sep 17 00:00:00 2001
From: Hugo Santos <hugosantos@nowhere.fake>
Date: Fri, 4 May 2007 18:43:30 +0000
Subject: [PATCH] fixed a race condition in TCP's WaitList Wait/Signal that was
 preventing Connect() from awake when it should. Reported by Francois Revol.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@21024 a95241bf-73f2-0310-859d-f6bbb57e9c96
---
 .../network/protocols/tcp/TCPEndpoint.cpp     | 20 +++++++++++++------
 .../network/protocols/tcp/TCPEndpoint.h       |  1 +
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/src/add-ons/kernel/network/protocols/tcp/TCPEndpoint.cpp b/src/add-ons/kernel/network/protocols/tcp/TCPEndpoint.cpp
index be04b408e2..5da10c6070 100644
--- a/src/add-ons/kernel/network/protocols/tcp/TCPEndpoint.cpp
+++ b/src/add-ons/kernel/network/protocols/tcp/TCPEndpoint.cpp
@@ -171,6 +171,7 @@ state_needs_finish(int32 state)
 
 WaitList::WaitList(const char *name)
 {
+	fCondition = 0;
 	fSem = create_sem(0, name);
 }
 
@@ -192,11 +193,17 @@ status_t
 WaitList::Wait(RecursiveLocker &locker, bigtime_t timeout, bool wakeNext)
 {
 	locker.Unlock();
-	status_t status = acquire_sem_etc(fSem, 1, B_ABSOLUTE_TIMEOUT
-		| B_CAN_INTERRUPT, timeout);
+
+	status_t status = B_OK;
+
+	while (status == B_OK && !atomic_test_and_set(&fCondition, 0, 1))
+		status = acquire_sem_etc(fSem, 1, B_ABSOLUTE_TIMEOUT | B_CAN_INTERRUPT,
+			timeout);
+
 	locker.Lock();
-	if (wakeNext && status == B_OK)
+	if (status == B_OK && wakeNext)
 		Signal();
+
 	return status;
 }
 
@@ -204,8 +211,8 @@ WaitList::Wait(RecursiveLocker &locker, bigtime_t timeout, bool wakeNext)
 void
 WaitList::Signal()
 {
-	release_sem_etc(fSem, 1, B_DO_NOT_RESCHEDULE
-		| B_RELEASE_IF_WAITING_ONLY);
+	atomic_or(&fCondition, 1);
+	release_sem_etc(fSem, 1, B_DO_NOT_RESCHEDULE | B_RELEASE_IF_WAITING_ONLY);
 }
 
 
@@ -418,7 +425,8 @@ TCPEndpoint::Connect(const sockaddr *address)
 	}
 
 	status = _WaitForEstablished(locker, absolute_timeout(timeout));
-	TRACE("  Connect(): Connection complete: %s", strerror(status));
+	TRACE("  Connect(): Connection complete: %s (timeout was %llu)",
+		strerror(status), timeout);
 	return posix_error(status);
 }
 
diff --git a/src/add-ons/kernel/network/protocols/tcp/TCPEndpoint.h b/src/add-ons/kernel/network/protocols/tcp/TCPEndpoint.h
index ddc1f43abf..a50fb68bf2 100644
--- a/src/add-ons/kernel/network/protocols/tcp/TCPEndpoint.h
+++ b/src/add-ons/kernel/network/protocols/tcp/TCPEndpoint.h
@@ -36,6 +36,7 @@ public:
 	void Signal();
 
 private:
+	int32 fCondition;
 	sem_id fSem;
 };