diff options
| -rw-r--r-- | drivers/fsi/fsi-master-hub.c | 21 | ||||
| -rw-r--r-- | drivers/fsi/fsi-master.h | 15 |
2 files changed, 33 insertions, 3 deletions
diff --git a/drivers/fsi/fsi-master-hub.c b/drivers/fsi/fsi-master-hub.c index 5e4cd3134bc0..5885fc4a1ef0 100644 --- a/drivers/fsi/fsi-master-hub.c +++ b/drivers/fsi/fsi-master-hub.c @@ -288,10 +288,19 @@ static int hub_master_probe(struct device *dev) hub_master_init(hub); rc = fsi_master_register(&hub->master); - if (!rc) - return 0; + if (rc) + goto err_release; + + /* At this point, fsi_master_register performs the device_initialize(), + * and holds the sole reference on master.dev. This means the device + * will be freed (via ->release) during any subsequent call to + * fsi_master_unregister. We add our own reference to it here, so we + * can perform cleanup (in _remove()) without it being freed before + * we're ready. + */ + get_device(&hub->master.dev); + return 0; - kfree(hub); err_release: fsi_slave_release_range(fsi_dev->slave, FSI_HUB_LINK_OFFSET, FSI_HUB_LINK_SIZE * links); @@ -306,6 +315,12 @@ static int hub_master_remove(struct device *dev) fsi_slave_release_range(hub->upstream->slave, hub->addr, hub->size); of_node_put(hub->master.dev.of_node); + /* + * master.dev will likely be ->release()ed after this, which free()s + * the hub + */ + put_device(&hub->master.dev); + return 0; } diff --git a/drivers/fsi/fsi-master.h b/drivers/fsi/fsi-master.h index 18bd4ad79356..ee0b46086026 100644 --- a/drivers/fsi/fsi-master.h +++ b/drivers/fsi/fsi-master.h @@ -37,6 +37,21 @@ struct fsi_master { #define dev_to_fsi_master(d) container_of(d, struct fsi_master, dev) +/** + * fsi_master registration & lifetime: the fsi_master_register() and + * fsi_master_unregister() functions will take ownership of the master, and + * ->dev in particular. The registration path performs a get_device(), which + * takes the first reference on the device. Similarly, the unregistration path + * performs a put_device(), which may well drop the last reference. + * + * This means that master implementations *may* need to hold their own + * reference (via get_device()) on master->dev. In particular, if the device's + * ->release callback frees the fsi_master, then fsi_master_unregister will + * invoke this free if no other reference is held. + * + * The same applies for the error path of fsi_master_register; if the call + * fails, dev->release will have been invoked. + */ extern int fsi_master_register(struct fsi_master *master); extern void fsi_master_unregister(struct fsi_master *master); |