From: Adrian Hunter Date: Mon, 8 Jun 2026 05:43:10 +0000 (+0300) Subject: i3c: master: Defer new-device registration out of DAA caller context X-Git-Url: http://git.ipfire.org/index.cgi?a=commitdiff_plain;h=3f79dac3ea1c30516fcc791770af034387c7f917;p=thirdparty%2Fkernel%2Flinux.git i3c: master: Defer new-device registration out of DAA caller context Master drivers may invoke i3c_master_do_daa_ext() during resume to re-run Dynamic Address Assignment. As well as assigning addresses to any newly arrived devices, this restores the dynamic address of devices that lost it across system suspend, so it has to run as part of the controller's resume path. A side effect of i3c_master_do_daa_ext() today is that it also registers any newly discovered I3C devices with the driver model inline, via i3c_master_register_new_i3c_devs(). Doing that from the resume path is problematic: a hot-join-capable device may join the bus during this same DAA, and registering it immediately would push driver model work (probing, sysfs, etc.) into the controller's resume context, where the rest of the system is not yet fully resumed and the controller driver is still partway through its own resume sequence. Decouple discovery from registration: add a reg_work work item to struct i3c_master_controller and have i3c_master_do_daa_ext() queue it on master->wq (the freezable workqueue) instead of calling i3c_master_register_new_i3c_devs() directly. The worker performs the registration only when the controller is not shutting_down, and is cancelled alongside hj_work in i3c_master_shutdown(). Because wq is freezable, any newly observed devices end up being registered after the system has finished resuming. i3c_master_register() also routes its initial post-bus-init registration through reg_work, using flush_work() to keep probe-time behavior synchronous. This keeps a single registration code path and ensures the worker is the only writer of desc->dev. Fixes: 3a379bbcea0af ("i3c: Add core I3C infrastructure") Signed-off-by: Adrian Hunter Reviewed-by: Frank Li Link: https://patch.msgid.link/20260608054312.10604-7-adrian.hunter@intel.com Signed-off-by: Alexandre Belloni --- diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c index c89a1921fcf3..ed749f9ee413 100644 --- a/drivers/i3c/master.c +++ b/drivers/i3c/master.c @@ -839,6 +839,7 @@ static void i3c_master_shutdown(struct i3c_master_controller *master) i3c_bus_maintenance_unlock(&master->bus); cancel_work_sync(&master->hj_work); + cancel_work_sync(&master->reg_work); } static void i3c_device_shutdown(struct device *dev) @@ -1838,6 +1839,16 @@ i3c_master_register_new_i3c_devs(struct i3c_master_controller *master) } } +static void i3c_master_reg_work_fn(struct work_struct *work) +{ + struct i3c_master_controller *master = container_of(work, typeof(*master), reg_work); + + i3c_bus_normaluse_lock(&master->bus); + if (!master->shutting_down) + i3c_master_register_new_i3c_devs(master); + i3c_bus_normaluse_unlock(&master->bus); +} + /** * i3c_master_do_daa_ext() - Dynamic Address Assignment (extended version) * @master: controller @@ -1878,9 +1889,7 @@ int i3c_master_do_daa_ext(struct i3c_master_controller *master, bool rstdaa) if (ret) goto out; - i3c_bus_normaluse_lock(&master->bus); - i3c_master_register_new_i3c_devs(master); - i3c_bus_normaluse_unlock(&master->bus); + queue_work(master->wq, &master->reg_work); out: i3c_master_rpm_put(master); @@ -3126,6 +3135,7 @@ int i3c_master_register(struct i3c_master_controller *master, goto err_put_dev; } INIT_WORK(&master->hj_work, i3c_master_hj_work_fn); + INIT_WORK(&master->reg_work, i3c_master_reg_work_fn); ret = i3c_master_bus_init(master); if (ret) @@ -3151,12 +3161,15 @@ int i3c_master_register(struct i3c_master_controller *master, /* * We're done initializing the bus and the controller, we can now - * register I3C devices discovered during the initial DAA. + * register I3C devices discovered during the initial DAA. Device + * registration is done via reg_work because that keeps a single + * registration code path and ensures the worker is the only writer + * of desc->dev. Flush the work to preserve synchronous probe-time + * behavior. */ master->init_done = true; - i3c_bus_normaluse_lock(&master->bus); - i3c_master_register_new_i3c_devs(master); - i3c_bus_normaluse_unlock(&master->bus); + queue_work(master->wq, &master->reg_work); + flush_work(&master->reg_work); if (master->ops->set_dev_nack_retry) device_create_file(&master->dev, &dev_attr_dev_nack_retry_count); diff --git a/include/linux/i3c/master.h b/include/linux/i3c/master.h index 77e63082b06e..8cdd7be505d3 100644 --- a/include/linux/i3c/master.h +++ b/include/linux/i3c/master.h @@ -523,6 +523,11 @@ struct i3c_master_controller_ops { * be done from a sleep-able context * @hj_work: work item used to run DAA after a Hot-Join event is detected. * Queued to @wq by i3c_master_queue_hotjoin() + * @reg_work: work item used to register newly discovered I3C devices with + * the driver model. Queued to @wq by i3c_master_do_daa_ext() so + * that device registration is deferred out of the DAA caller's + * context (notably the resume path), and is skipped if the + * controller is shutting down * @dev_nack_retry_count: retry count when slave device nack * * A &struct i3c_master_controller has to be registered to the I3C subsystem @@ -548,6 +553,7 @@ struct i3c_master_controller { struct i3c_bus bus; struct workqueue_struct *wq; struct work_struct hj_work; + struct work_struct reg_work; unsigned int dev_nack_retry_count; };