soundwire: bus: fix device number leak on errors

If the programming of the dev_number fails due to an IO error, a new
device_number will be assigned, resulting in a leak.

Make sure we only assign a device_number once per Slave device.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200113225637.17313-1-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index 66fd09e..6106577 100644 (file)
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -456,26 +456,35 @@ err:
 static int sdw_assign_device_num(struct sdw_slave *slave)
 {
        int ret, dev_num;
+       bool new_device = false;
 
        /* check first if device number is assigned, if so reuse that */
        if (!slave->dev_num) {
-               mutex_lock(&slave->bus->bus_lock);
-               dev_num = sdw_get_device_num(slave);
-               mutex_unlock(&slave->bus->bus_lock);
-               if (dev_num < 0) {
-                       dev_err(slave->bus->dev, "Get dev_num failed: %d\n",
-                               dev_num);
-                       return dev_num;
+               if (!slave->dev_num_sticky) {
+                       mutex_lock(&slave->bus->bus_lock);
+                       dev_num = sdw_get_device_num(slave);
+                       mutex_unlock(&slave->bus->bus_lock);
+                       if (dev_num < 0) {
+                               dev_err(slave->bus->dev, "Get dev_num failed: %d\n",
+                                       dev_num);
+                               return dev_num;
+                       }
+                       slave->dev_num = dev_num;
+                       slave->dev_num_sticky = dev_num;
+                       new_device = true;
+               } else {
+                       slave->dev_num = slave->dev_num_sticky;
                }
-       } else {
+       }
+
+       if (!new_device)
                dev_info(slave->bus->dev,
-                        "Slave already registered dev_num:%d\n",
+                        "Slave already registered, reusing dev_num:%d\n",
                         slave->dev_num);
 
-               /* Clear the slave->dev_num to transfer message on device 0 */
-               dev_num = slave->dev_num;
-               slave->dev_num = 0;
-       }
+       /* Clear the slave->dev_num to transfer message on device 0 */
+       dev_num = slave->dev_num;
+       slave->dev_num = 0;
 
        ret = sdw_write(slave, SDW_SCP_DEVNUMBER, dev_num);
        if (ret < 0) {
@@ -485,7 +494,7 @@ static int sdw_assign_device_num(struct sdw_slave *slave)
        }
 
        /* After xfer of msg, restore dev_num */
-       slave->dev_num = dev_num;
+       slave->dev_num = slave->dev_num_sticky;
 
        return 0;
 }

diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
index b7c9eca..b451bb6 100644 (file)
--- a/include/linux/soundwire/sdw.h
+++ b/include/linux/soundwire/sdw.h
@@ -546,7 +546,8 @@ struct sdw_slave_ops {
  * @debugfs: Slave debugfs
  * @node: node for bus list
  * @port_ready: Port ready completion flag for each Slave port
- * @dev_num: Device Number assigned by Bus
+ * @dev_num: Current Device Number, values can be 0 or dev_num_sticky
+ * @dev_num_sticky: one-time static Device Number assigned by Bus
  * @probed: boolean tracking driver state
  * @probe_complete: completion utility to control potential races
  * on startup between driver probe/initialization and SoundWire
@@ -575,6 +576,7 @@ struct sdw_slave {
        struct list_head node;
        struct completion *port_ready;
        u16 dev_num;
+       u16 dev_num_sticky;
        bool probed;
        struct completion probe_complete;
        struct completion enumeration_complete;