trying to fix frontend thread start/stop problems

1 files changed, 49 insertions, 23 deletions

diff --git a/linux/drivers/media/dvb/dvb-core/dvb_frontend.c b/linux/drivers/media/dvb/dvb-core/dvb_frontend.c
index ee95bb16d..73184e1c2 100644
--- a/linux/drivers/media/dvb/dvb-core/dvb_frontend.c
+++ b/linux/drivers/media/dvb/dvb-core/dvb_frontend.c
@@ -65,7 +65,7 @@ struct dvb_frontend_data {
 	struct semaphore sem;
 	struct list_head list_head;
 	wait_queue_head_t wait_queue;
-	struct task_struct *thread;
+	pid_t thread_pid;
 	unsigned long release_jiffies;
 	unsigned long lost_sync_jiffies;
 	int bending;
@@ -437,7 +437,7 @@ int dvb_frontend_thread (void *data)
 
 	dvb_kernel_thread_setup (name);
 
-	fe->thread = current;
+	fe->thread_pid = current->pid;
 	fe->lost_sync_count = -1;
 
 	dvb_call_frontend_notifiers (fe, 0);
@@ -447,11 +447,11 @@ int dvb_frontend_thread (void *data)
 		up (&fe->sem);      /* is locked when we enter the thread... */
 
 		interruptible_sleep_on_timeout (&fe->wait_queue, delay);
+		if (signal_pending(current))
+			break;
 
-		if (down_interruptible (&fe->sem)) {
-			fe->thread = NULL;
-			return -ERESTARTSYS;
-		}
+		if (down_interruptible (&fe->sem))
+			break;
 
 		if (fe->lost_sync_count == -1)
 			continue;
@@ -493,7 +493,11 @@ int dvb_frontend_thread (void *data)
 		dvb_frontend_internal_ioctl (&fe->frontend, FE_SLEEP, NULL); 
 
 	up (&fe->sem);
-	fe->thread = NULL;
+
+	fe->thread_pid = 0;
+	mb();
+
+	wake_up_interruptible (&fe->wait_queue);
 	return 0;
 }
 
@@ -503,32 +507,54 @@ void dvb_frontend_stop (struct dvb_frontend_data *fe)
 {
 	dprintk ("%s\n", __FUNCTION__);
 
-	while (fe->thread) {
-		fe->exit = 1;
-		wake_up_interruptible (&fe->wait_queue);
-		set_current_state(TASK_INTERRUPTIBLE);
-		schedule_timeout (5);
-		if (signal_pending(current))
-			break;
-	};
+	fe->exit = 1;
+	mb();
+
+	if (!fe->thread_pid)
+		return;
+
+	/* check if the thread is really alive */
+	if (kill_proc(fe->thread_pid, 0, 1) == -ESRCH) {
+		printk("dvb_frontend_stop: thread PID %d already died\n",
+				fe->thread_pid);
+		/* make sure the mutex was not held by the thread */
+		init_MUTEX (&fe->sem);
+		return;
+	}
+
+	wake_up_interruptible(&fe->wait_queue);
+	interruptible_sleep_on(&fe->wait_queue);
+
+	/* paranoia check */
+	if (fe->thread_pid)
+		printk("dvb_frontend_stop: warning: thread PID %d won't exit\n",
+				fe->thread_pid);
 }
 
 
 static
-void dvb_frontend_start (struct dvb_frontend_data *fe)
+int dvb_frontend_start (struct dvb_frontend_data *fe)
 {
 	dprintk ("%s\n", __FUNCTION__);
 
-	if (fe->thread)
-		dvb_frontend_stop (fe);
+	if (fe->thread_pid) {
+		if (!fe->exit)
+			return 0;
+		else
+			dvb_frontend_stop (fe);
+	}
 
+	if (signal_pending(current))
+		return -EINTR;
 	if (down_interruptible (&fe->sem))
-		return;
+		return -EINTR;
 
 	fe->exit = 0;
-	fe->thread = (void*) ~0;
+	fe->thread_pid = 0;
+	mb();
 
 	kernel_thread (dvb_frontend_thread, fe, 0);
+	return 0;
 }
 
 
@@ -606,12 +632,12 @@ int dvb_frontend_open (struct inode *inode, struct file *file)
 		return ret;
 
 	if ((file->f_flags & O_ACCMODE) != O_RDONLY) {
-		dvb_frontend_start (fe);
+		ret = dvb_frontend_start (fe);
 
 		/*  empty event queue */
-		fe->events.eventr = fe->events.eventw;
+		fe->events.eventr = fe->events.eventw = 0;
 	}
-	
+
 	return ret;
 }