From 4620b4e54cd32935a3b477c1da74b09ce704734f Mon Sep 17 00:00:00 2001
From: cloudwalk <cloudwalk@d7cf8633-e32d-0410-b094-e92efae38249>
Date: Sat, 18 Jul 2020 19:45:09 +0000
Subject: [PATCH] cmd: Use reentrant mutex for cbufs. Fixes deadlock when
 expanding aliases in some situations

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@12839 d7cf8633-e32d-0410-b094-e92efae38249
---
 cmd.c        | 9 ++++++---
 cmd.h        | 2 +-
 sys_shared.c | 4 ++--
 3 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/cmd.c b/cmd.c
index b7baf77e..6e2b6479 100644
--- a/cmd.c
+++ b/cmd.c
@@ -49,12 +49,12 @@ qboolean host_stuffcmdsrun = false;
 
 void Cbuf_Lock(cmd_state_t *cmd)
 {
-	Thread_AtomicLock(&cmd->text_lock);
+	Thread_LockMutex(cmd->text_mutex);
 }
 
 void Cbuf_Unlock(cmd_state_t *cmd)
 {
-	Thread_AtomicUnlock(&cmd->text_lock);
+	Thread_UnlockMutex(cmd->text_mutex);
 }
 
 
@@ -1512,16 +1512,19 @@ void Cmd_Init(void)
 	cmd_client.cvars_flagsmask = CVAR_CLIENT | CVAR_SERVER;
 	cmd_client.cmd_flags = CMD_CLIENT | CMD_CLIENT_FROM_SERVER | CMD_SERVER_FROM_CLIENT;
 	cmd_client.userdefined = &cmd_userdefined_all;
+	cmd_client.text_mutex = Thread_CreateMutex();
 	// dedicated server console can only see server cvars, there is no client
 	cmd_server.cvars = &cvars_all;
 	cmd_server.cvars_flagsmask = CVAR_SERVER;
 	cmd_server.cmd_flags = CMD_SERVER;
 	cmd_server.userdefined = &cmd_userdefined_all;
+	cmd_server.text_mutex = Thread_CreateMutex();
 	// server commands received from clients have no reason to access cvars, cvar expansion seems perilous.
 	cmd_serverfromclient.cvars = &cvars_null;
 	cmd_serverfromclient.cvars_flagsmask = 0;
 	cmd_serverfromclient.cmd_flags = CMD_SERVER_FROM_CLIENT | CMD_USERINFO;
 	cmd_serverfromclient.userdefined = &cmd_userdefined_null;
+	cmd_serverfromclient.text_mutex = Thread_CreateMutex();
 
 //
 // register our commands
@@ -1576,7 +1579,7 @@ void Cmd_Shutdown(void)
 	{
 		cmd_state_t *cmd = cmd_iter->cmd;
 
-		if (cmd->text_lock)
+		if (cmd->text_mutex)
 		{
 			// we usually have this locked when we get here from Host_Quit_f
 			Cbuf_Unlock(cmd);
diff --git a/cmd.h b/cmd.h
index 40b71958..9016c27c 100644
--- a/cmd.h
+++ b/cmd.h
@@ -114,7 +114,7 @@ typedef struct cmd_state_s
 
 	sizebuf_t text;
 	unsigned char text_buf[CMDBUFSIZE];
-	Thread_SpinLock text_lock;
+	void *text_mutex;
 
 	int argc;
 	const char *argv[MAX_ARGS];
diff --git a/sys_shared.c b/sys_shared.c
index 6b3f8c5a..4898c82a 100644
--- a/sys_shared.c
+++ b/sys_shared.c
@@ -48,9 +48,9 @@ char *Sys_TimeString(const char *timeformat)
 void Sys_Quit (int returnvalue)
 {
 	// Unlock mutexes because the quit command may jump directly here, causing a deadlock
-	if (cmd_client.text_lock)
+	if (cmd_client.text_mutex)
 		Cbuf_Unlock(&cmd_client);
-	if (cmd_server.text_lock)
+	if (cmd_server.text_mutex)
 		Cbuf_Unlock(&cmd_server);
 	SV_UnlockThreadMutex();
 	TaskQueue_Frame(true);
-- 
2.39.2