1 files changed, 21 insertions, 3 deletions

diff --git a/drivers/media/dvb/dvb-core/dvb_ca_en50221.c b/drivers/media/dvb/dvb-core/dvb_ca_en50221.c
index 98ee16773ff2..7e3aeaa7370f 100644
--- a/drivers/media/dvb/dvb-core/dvb_ca_en50221.c
+++ b/drivers/media/dvb/dvb-core/dvb_ca_en50221.c
@@ -93,6 +93,9 @@ struct dvb_ca_slot {
 	/* current state of the CAM */
 	int slot_state;
 
+	/* mutex used for serializing access to one CI slot */
+	struct mutex slot_lock;
+
 	/* Number of CAMCHANGES that have occurred since last processing */
 	atomic_t camchange_count;
 
@@ -711,14 +714,20 @@ static int dvb_ca_en50221_write_data(struct dvb_ca_private *ca, int slot, u8 * b
 	dprintk("%s\n", __func__);
 
 
-	// sanity check
+	/* sanity check */
 	if (bytes_write > ca->slot_info[slot].link_buf_size)
 		return -EINVAL;
 
-	/* check if interface is actually waiting for us to read from it, or if a read is in progress */
+	/* it is possible we are dealing with a single buffer implementation,
+	   thus if there is data available for read or if there is even a read
+	   already in progress, we do nothing but awake the kernel thread to
+	   process the data if necessary. */
 	if ((status = ca->pub->read_cam_control(ca->pub, slot, CTRLIF_STATUS)) < 0)
 		goto exitnowrite;
 	if (status & (STATUSREG_DA | STATUSREG_RE)) {
+		if (status & STATUSREG_DA)
+			dvb_ca_en50221_thread_wakeup(ca);
+
 		status = -EAGAIN;
 		goto exitnowrite;
 	}
@@ -987,6 +996,8 @@ static int dvb_ca_en50221_thread(void *data)
 		/* go through all the slots processing them */
 		for (slot = 0; slot < ca->slot_count; slot++) {
 
+			mutex_lock(&ca->slot_info[slot].slot_lock);
+
 			// check the cam status + deal with CAMCHANGEs
 			while (dvb_ca_en50221_check_camstatus(ca, slot)) {
 				/* clear down an old CI slot if necessary */
@@ -1122,7 +1133,7 @@ static int dvb_ca_en50221_thread(void *data)
 
 			case DVB_CA_SLOTSTATE_RUNNING:
 				if (!ca->open)
-					continue;
+					break;
 
 				// poll slots for data
 				pktcount = 0;
@@ -1146,6 +1157,8 @@ static int dvb_ca_en50221_thread(void *data)
 				}
 				break;
 			}
+
+			mutex_unlock(&ca->slot_info[slot].slot_lock);
 		}
 	}
 
@@ -1181,6 +1194,7 @@ static int dvb_ca_en50221_io_do_ioctl(struct inode *inode, struct file *file,
 	switch (cmd) {
 	case CA_RESET:
 		for (slot = 0; slot < ca->slot_count; slot++) {
+			mutex_lock(&ca->slot_info[slot].slot_lock);
 			if (ca->slot_info[slot].slot_state != DVB_CA_SLOTSTATE_NONE) {
 				dvb_ca_en50221_slot_shutdown(ca, slot);
 				if (ca->flags & DVB_CA_EN50221_FLAG_IRQ_CAMCHANGE)
@@ -1188,6 +1202,7 @@ static int dvb_ca_en50221_io_do_ioctl(struct inode *inode, struct file *file,
 								     slot,
 								     DVB_CA_EN50221_CAMCHANGE_INSERTED);
 			}
+			mutex_unlock(&ca->slot_info[slot].slot_lock);
 		}
 		ca->next_read_slot = 0;
 		dvb_ca_en50221_thread_wakeup(ca);
@@ -1308,7 +1323,9 @@ static ssize_t dvb_ca_en50221_io_write(struct file *file,
 				goto exit;
 			}
 
+			mutex_lock(&ca->slot_info[slot].slot_lock);
 			status = dvb_ca_en50221_write_data(ca, slot, fragbuf, fraglen + 2);
+			mutex_unlock(&ca->slot_info[slot].slot_lock);
 			if (status == (fraglen + 2)) {
 				written = 1;
 				break;
@@ -1664,6 +1681,7 @@ int dvb_ca_en50221_init(struct dvb_adapter *dvb_adapter,
 		ca->slot_info[i].slot_state = DVB_CA_SLOTSTATE_NONE;
 		atomic_set(&ca->slot_info[i].camchange_count, 0);
 		ca->slot_info[i].camchange_type = DVB_CA_EN50221_CAMCHANGE_REMOVED;
+		mutex_init(&ca->slot_info[i].slot_lock);
 	}
 
 	if (signal_pending(current)) {