[linux-dvb] dmxdev_filter_t mutex

[Matt Davis <matt@Helius.COM>]

The patch below adds a mutex to dmxdev_filter_t.  When using the DVB driver we 
had problems with multiple processes (setting up a number of different 
section/PES filters) reading from the demux.  This was due to DmxDevRead 
locking the dmxdev mutex so only one read at a time was allowed.  This patch 
adds a filter specific mutex which allows multiple reads at the same time.


[mdavis@tun cvs]$ diff -ru DVB/ temp/DVB/
diff -ru DVB/driver/dmxdev.c temp/DVB/driver/dmxdev.c
--- DVB/driver/dmxdev.c	Thu Aug  1 11:46:11 2002
+++ temp/DVB/driver/dmxdev.c	Thu Aug 15 12:49:57 2002
@@ -722,6 +726,7 @@
                 return -EMFILE;
 	}
         dmxdevfilter=&dmxdev->filter[i];
+	sema_init(&dmxdevfilter->mutex, 1);
 	file->private_data=dmxdevfilter;
 
 	DmxDevBufferInit(&dmxdevfilter->buffer);
@@ -747,6 +752,11 @@
 	        up(&dmxdev->mutex);
 	        return -EINVAL;
         }
+	
+	if (down_interruptible(&dmxdevfilter->mutex)) {
+	        up(&dmxdev->mutex);
+	        return -ERESTARTSYS;
+	}
 
         DmxDevFilterStop(dmxdevfilter);
 	DmxDevFilterReset(dmxdevfilter);
@@ -761,6 +771,7 @@
 	}
 	DmxDevFilterStateSet(dmxdevfilter, DMXDEV_STATE_FREE);
 	wake_up(&dmxdevfilter->buffer.queue);
+	up(&dmxdevfilter->mutex);
 	up(&dmxdev->mutex);
 	//printk("free filters = %d\n", DmxDevFilterNum(dmxdev));
         return 0;
@@ -907,7 +924,7 @@
         dmxdev_filter_t *dmxdevfilter=DmxDevFile2Filter(dmxdev, file);
 	int ret=0;
 
-        if (down_interruptible(&dmxdev->mutex))
+        if (down_interruptible(&dmxdevfilter->mutex))
 		return -ERESTARTSYS;
 
 	if (dmxdevfilter->type==DMXDEV_TYPE_SEC)
@@ -916,7 +933,7 @@
 	        ret=DmxDevBufferRead(&dmxdevfilter->buffer, 
 				     file->f_flags&O_NONBLOCK, 
 				     buf, count, ppos);
-        up(&dmxdev->mutex);
+        up(&dmxdevfilter->mutex);
 	return ret;
 }
 
@@ -937,14 +954,26 @@
 
 	switch (cmd) {
 	case DMX_START: 
+	        if (down_interruptible(&dmxdevfilter->mutex)) {
+	              up(&dmxdev->mutex);
+		      return -ERESTARTSYS;
+	        }
+
 	        if (dmxdevfilter->state<DMXDEV_STATE_SET)
 		        ret=-EINVAL;
 		else
 		        ret=DmxDevFilterStart(dmxdevfilter);
+
+		up(&dmxdevfilter->mutex);
 		break;
 
 	case DMX_STOP: 
+	        if (down_interruptible(&dmxdevfilter->mutex)) {
+	              up(&dmxdev->mutex);
+		      return -ERESTARTSYS;
+	        }
 		ret=DmxDevFilterStop(dmxdevfilter);
+		up(&dmxdevfilter->mutex);
 		break;
 
 	case DMX_SET_FILTER: 
@@ -954,8 +983,14 @@
 	        if (copy_from_user(&params, parg, sizeof(params)))
 			
 		        ret=-EFAULT;
-		else
+		else {
+	                if (down_interruptible(&dmxdevfilter->mutex)) {
+	                        up(&dmxdev->mutex);
+				return -ERESTARTSYS;
+			}
 		        ret=DmxDevFilterSet(dmxdev, dmxdevfilter, &params);
+			up(&dmxdevfilter->mutex);
+		}
 		break;
 	}
 
@@ -965,13 +1000,24 @@
 		
 		if (copy_from_user(&params, parg, sizeof(params)))
 		        ret=-EFAULT;
-		else
+		else {
+	                if (down_interruptible(&dmxdevfilter->mutex)) {
+	                      up(&dmxdev->mutex);
+			      return -ERESTARTSYS;
+			}
 			ret=DmxDevPesFilterSet(dmxdev, dmxdevfilter, &params);
+			up(&dmxdevfilter->mutex);
+		}
 		break;
 	}
 
 	case DMX_SET_BUFFER_SIZE: 
+	        if (down_interruptible(&dmxdevfilter->mutex)) {
+	              up(&dmxdev->mutex);
+		      return -ERESTARTSYS;
+	        }
 	        ret=DmxDevSetBufferSize(dmxdevfilter, arg);
+		up(&dmxdevfilter->mutex);
 		break;
         
         case DMX_GET_EVENT: 
diff -ru DVB/driver/dmxdev.h temp/DVB/driver/dmxdev.h
--- DVB/driver/dmxdev.h	Mon Oct 29 05:51:26 2001
+++ temp/DVB/driver/dmxdev.h	Wed Aug  7 15:08:30 2002
@@ -96,6 +96,8 @@
         struct dmxdev_s *dev;
         dmxdev_buffer_t buffer;
 
+        struct semaphore mutex;
+
         // only for sections
         struct timer_list timer;
         int todo;


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