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Subject[PATCH] soundwire: bus: fix device number leak on errors
Date
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>
---
drivers/soundwire/bus.c | 37 ++++++++++++++++++++++-------------
include/linux/soundwire/sdw.h | 4 +++-
2 files changed, 26 insertions(+), 15 deletions(-)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index be5d437058ed..8f973e70e6f7 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -456,26 +456,35 @@ static int sdw_get_device_num(struct sdw_slave *slave)
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 b7c9eca4332a..b451bb622335 100644
--- 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;
--
2.20.1
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