i2c: ensure timely release of driver-allocated resources

More and more drivers rely on devres to manage their resources, however
if bus' probe() and release() methods are not trivial and control some
of resources as well (for example enable or disable clocks, or attach
device to a power domain), we need to make sure that driver-allocated
resources are released immediately after driver's remove() method
returns, and not postponed until driver core gets around to releasing
resources. To fix that we open a new devres group before calling
driver's probe() and explicitly release it when we return from driver's
remove().

Tested-by: Jeff LaBundy <jeff@labundy.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 5c16083694bf2abc730b0d6f49694b7d50b34910..4351bf529d0f4ff26005dc2c0071510c56060f45 100644 (file)
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -539,6 +539,13 @@ static int i2c_device_probe(struct device *dev)
        if (status)
                goto err_clear_wakeup_irq;
 
+       client->devres_group_id = devres_open_group(&client->dev, NULL,
+                                                   GFP_KERNEL);
+       if (!client->devres_group_id) {
+               status = -ENOMEM;
+               goto err_detach_pm_domain;
+       }
+
        /*
         * When there are no more users of probe(),
         * rename probe_new to probe.
@@ -551,11 +558,21 @@ static int i2c_device_probe(struct device *dev)
        else
                status = -EINVAL;
 
+       /*
+        * Note that we are not closing the devres group opened above so
+        * even resources that were attached to the device after probe is
+        * run are released when i2c_device_remove() is executed. This is
+        * needed as some drivers would allocate additional resources,
+        * for example when updating firmware.
+        */
+
        if (status)
-               goto err_detach_pm_domain;
+               goto err_release_driver_resources;
 
        return 0;
 
+err_release_driver_resources:
+       devres_release_group(&client->dev, client->devres_group_id);
 err_detach_pm_domain:
        dev_pm_domain_detach(&client->dev, true);
 err_clear_wakeup_irq:
@@ -584,6 +601,8 @@ static int i2c_device_remove(struct device *dev)
                        dev_warn(dev, "remove failed (%pe), will be ignored\n", ERR_PTR(status));
        }
 
+       devres_release_group(&client->dev, client->devres_group_id);
+
        dev_pm_domain_detach(&client->dev, true);
 
        dev_pm_clear_wake_irq(&client->dev);

diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index e5d8b9dad6bf26c0469481be920a6739cd1049d0..e8f2ac8c9c3d4aa254305c8417d14c1dbefd7a56 100644 (file)
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -309,6 +309,8 @@ struct i2c_driver {
  *     userspace_devices list
  * @slave_cb: Callback when I2C slave mode of an adapter is used. The adapter
  *     calls it to pass on slave events to the slave driver.
+ * @devres_group_id: id of the devres group that will be created for resources
+ *     acquired when probing this device.
  *
  * An i2c_client identifies a single device (i.e. chip) connected to an
  * i2c bus. The behaviour exposed to Linux is defined by the driver
@@ -337,6 +339,7 @@ struct i2c_client {
 #if IS_ENABLED(CONFIG_I2C_SLAVE)
        i2c_slave_cb_t slave_cb;        /* callback for slave mode      */
 #endif
+       void *devres_group_id;          /* ID of probe devres group     */
 };
 #define to_i2c_client(d) container_of(d, struct i2c_client, dev)