FAILED: patch "[PATCH] i3c: master: Fix recursive locking during device registration" failed to apply to 6.12-stable tree

PATCH New [email protected] 2 participants 4 messages Sep 4 – Sep 10

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[email protected]

author maintainer

2026-09-04 04:37 UTC #0 lore raw

The patch below does not apply to the 6.12-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x 456f832e5fc26fbfd3b8200fd4553eee520cc377
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026090419-hunchback-antics-d9e3@gregkh' --subject-prefix 'PATCH 6.12.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 456f832e5fc26fbfd3b8200fd4553eee520cc377 Mon Sep 17 00:00:00 2001
From: Adrian Hunter <[email protected]>
Date: Fri, 7 Aug 2026 17:56:25 +0300
Subject: [PATCH] i3c: master: Fix recursive locking during device registration

i3c_master_register_new_i3c_devs() registers newly discovered devices while holding i3c_bus_normaluse_lock(), a down_read(). device_register() can immediately probe the device, and probe callbacks typically invoke I3C helpers that take i3c_bus_normaluse_lock() again, leading to a recursive acquisition of the same rwsem. rwsems do not support recursive read locking and can deadlock when a writer is waiting. See the "Recursive read locks" section of Documentation/locking/lockdep-design.rst.

For example, with Intel LPSS I3C, LOCKDEP generates a WARNING like:

  # echo intel-lpss-i3c.0 > /sys/bus/platform/drivers/mipi-i3c-hci/unbind
  # echo intel-lpss-i3c.0 > /sys/bus/platform/drivers/mipi-i3c-hci/bind
  WARNING: possible recursive locking detected
  kworker/5:1/94 is trying to acquire lock:
  ffff88811c810d78 (&i3cbus->lock){++++}-{4:4}, at: i3c_device_match_id+0x45/0x370
  but task is already holding lock:
  ffff88811c810d78 (&i3cbus->lock){++++}-{4:4}, at: i3c_master_reg_work_fn+0x21/0x5f0

Fix this by separating device creation from device registration. Populate desc->dev under the maintenance lock, collect the devices that still need registration into a local list, then release the lock before calling device_register(). Finally retake the lock and clean up any devices that failed to register.

Use the maintenance lock rather than the normal-use lock while adding device objects. A write-side maintenance lock prevents readers from observing a partially initialized desc->dev during initial device population, or desc->dev disappearing if registration fails.

The local list requires a list node, so add a list node member to struct i3c_device.

Fixes 3a379bbcea0a ("i3c: Add core I3C infrastructure")

Cc [email protected]

Signed-off-by Adrian Hunter <[email protected]>

Reviewed-by Frank Li <[email protected]>

Link https://patch.msgid.link/[email protected] open here

Signed-off-by Alexandre Belloni <[email protected]>

drivers/i3c/master.c +33 ~~-12~~

index f485b98805cf..d2fb1a110521 100644
@@ -2069,12 +2069,21 @@ static int i3c_master_early_i3c_dev_add(struct i3c_master_controller *master,
 static void
 i3c_master_register_new_i3c_devs(struct i3c_master_controller *master)
 {
+	struct i3c_device *i3cdev, *tmp;
 	struct i3c_dev_desc *desc;
+	LIST_HEAD(i3c_unreg_devs);
 	int ret;
 
 	if (!master->init_done)
 		return;
 
+	i3c_bus_maintenance_lock(&master->bus);
+
+	if (master->shutting_down) {
+		i3c_bus_maintenance_unlock(&master->bus);
+		return;
+	}
+
 	i3c_bus_for_each_i3cdev(&master->bus, desc) {
 		if (desc->dev || !desc->info.dyn_addr || desc == master->this)
 			continue;

@@ -2104,25 +2113,37 @@ i3c_master_register_new_i3c_devs(struct i3c_master_controller *master)
 		if (desc->boardinfo)
 			device_set_node(&desc->dev->dev, desc->boardinfo->fwnode);
 
-		ret = device_register(&desc->dev->dev);
-		if (ret) {
-			dev_err(&master->dev,
-				"Failed to add I3C device (err = %d)\n", ret);
-			desc->dev->desc = NULL;
-			put_device(&desc->dev->dev);
-			desc->dev = NULL;
-		}
+		list_add_tail(&desc->dev->node, &i3c_unreg_devs);
 	}
+
+	i3c_bus_maintenance_unlock(&master->bus);
+
+	list_for_each_entry_safe(i3cdev, tmp, &i3c_unreg_devs, node) {
+		ret = device_register(&i3cdev->dev);
+		if (ret)
+			dev_err(&master->dev, "Failed to add I3C device (err = %d)\n", ret);
+		else
+			list_del_init(&i3cdev->node);
+	}
+
+	i3c_bus_maintenance_lock(&master->bus);
+
+	list_for_each_entry_safe(i3cdev, tmp, &i3c_unreg_devs, node) {
+		list_del(&i3cdev->node);
+		desc = i3cdev->desc;
+		i3cdev->desc = NULL;
+		put_device(&i3cdev->dev);
+		desc->dev = NULL;
+	}
+
+	i3c_bus_maintenance_unlock(&master->bus);
 }
 
 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_register_new_i3c_devs(master);
 }
 
 /**

include/linux/i3c/master.h +3 -0

index 2dc139a217bf..26535beb1e77 100644
@@ -238,6 +238,8 @@ struct i3c_dev_desc {
  *	  every time the I3C device is rediscovered with a different dynamic
  *	  address assigned
  * @bus: I3C bus this device is attached to
+ * @node: unregistered device list node, only for use by
+ *	  i3c_master_register_new_i3c_devs(), it is not protected by a lock
  *
  * I3C device object exposed to I3C device drivers. The takes care of linking
  * this object to the relevant &struct_i3c_dev_desc one.

@@ -248,6 +250,7 @@ struct i3c_device {
 	struct device dev;
 	struct i3c_dev_desc *desc;
 	struct i3c_bus *bus;
+	struct list_head node;
 };
 
 /*

Sasha Levin

maintainer

2026-09-10 00:17 UTC #1 lore raw

PATCH 1/3 i3c: master: Replace WARN_ON() with dev_err() in i3c_dev_free_ibi_locked()

From: Adrian Hunter <[email protected]>

[ Upstream commit 471895799c2f46688792e175ced936ffeb6cdf01 ]

IBI disable failures are not indicative of a software bug, so using WARN_ON() is not appropriate. Replace these warnings with dev_err().

Signed-off-by Adrian Hunter <[email protected]>

Reviewed-by Frank Li <[email protected]>

Link https://patch.msgid.link/[email protected] open here

Signed-off-by Alexandre Belloni <[email protected]>

Stable-dep-of: 456f832e5fc2 ("i3c: master: Fix recursive locking during device registration")

Signed-off-by Sasha Levin <[email protected]>

---
 drivers/i3c/master.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

drivers/i3c/master.c +5 -2

index 6eec1e6fb139f..067dd5946d512 100644
@@ -3054,8 +3054,11 @@ void i3c_dev_free_ibi_locked(struct i3c_dev_desc *dev)
 	if (!dev->ibi)
 		return;
 
-	if (WARN_ON(dev->ibi->enabled))
-		WARN_ON(i3c_dev_disable_ibi_locked(dev));
+	if (dev->ibi->enabled) {
+		dev_err(&master->dev, "Freeing IBI that is still enabled\n");
+		if (i3c_dev_disable_ibi_locked(dev))
+			dev_err(&master->dev, "Failed to disable IBI before freeing\n");
+	}
 
 	master->ops->free_ibi(dev);

Signature · 1 line

2.53.0

Sasha Levin

maintainer

2026-09-10 00:17 UTC #2 lore raw

PATCH 2/3 i3c: master: Defer new-device registration out of DAA caller context

From: Adrian Hunter <[email protected]>

[ Upstream commit 3f79dac3ea1c30516fcc791770af034387c7f917 ]

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 <[email protected]>

Reviewed-by Frank Li <[email protected]>

Link https://patch.msgid.link/[email protected] open here

Signed-off-by Alexandre Belloni <[email protected]>

Stable adaptation for 6.12:

Use the existing i3c_master_do_daa() API because this branch lacks the extended DAA API and the runtime-PM and core hot-join prerequisites. Keep the registration worker introduced by this commit unchanged. Initialize reg_work in i3c_master_register() and preserve the initial registration flush.

Add the shutting_down gate and cancel reg_work directly in the existing i3c_master_unregister() path, before device and bus cleanup. Queue DAA registration while holding the maintenance lock so unregister cannot cancel the work and then race with a late enqueue. No additional helper functions or core hot-join/shutdown callbacks are introduced.

Include the two device_register() failure-path pointer clears from 74be657d98a8d ("i3c: master: Fix device_register() error path"), which are required by the target's registration cleanup rewrite. Keep the existing OF node handling; the target merges cleanly without the unified firmware property conversion.

This prepares the tree for 456f832e5fc2 ("i3c: master: Fix recursive locking during device registration").

Stable-dep-of: 456f832e5fc2 ("i3c: master: Fix recursive locking during device registration")

Signed-off-by Sasha Levin <[email protected]>

---
 drivers/i3c/master.c       | 48 +++++++++++++++++++++++++++-----------
 include/linux/i3c/master.h |  6 +++++
 2 files changed, 41 insertions(+), 13 deletions(-)

drivers/i3c/master.c +35 ~~-13~~

index 067dd5946d512..9103dc77a4459 100644
@@ -1689,11 +1689,23 @@ i3c_master_register_new_i3c_devs(struct i3c_master_controller *master)
 		if (ret) {
 			dev_err(&master->dev,
 				"Failed to add I3C device (err = %d)\n", ret);
+			desc->dev->desc = NULL;
 			put_device(&desc->dev->dev);
+			desc->dev = NULL;
 		}
 	}
 }
 
+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() - do a DAA (Dynamic Address Assignment)
  * @master: master doing the DAA

@@ -1714,17 +1726,17 @@ int i3c_master_do_daa(struct i3c_master_controller *master)
 	int ret;
 
 	i3c_bus_maintenance_lock(&master->bus);
-	ret = master->ops->do_daa(master);
-	i3c_bus_maintenance_unlock(&master->bus);
-
-	if (ret)
-		return ret;
+	if (master->shutting_down)
+		ret = -ENODEV;
+	else
+		ret = master->ops->do_daa(master);
 
-	i3c_bus_normaluse_lock(&master->bus);
-	i3c_master_register_new_i3c_devs(master);
-	i3c_bus_normaluse_unlock(&master->bus);
+	/* Serialize queuing with cancellation during unregister. */
+	if (!ret)
+		queue_work(master->wq, &master->reg_work);
+	i3c_bus_maintenance_unlock(&master->bus);
 
-	return 0;
+	return ret;
 }
 EXPORT_SYMBOL_GPL(i3c_master_do_daa);

@@ -2817,6 +2829,7 @@ int i3c_master_register(struct i3c_master_controller *master,
 	master->dev.release = i3c_masterdev_release;
 	master->ops = ops;
 	master->secondary = secondary;
+	master->shutting_down = false;
 	INIT_LIST_HEAD(&master->boardinfo.i2c);
 	INIT_LIST_HEAD(&master->boardinfo.i3c);

@@ -2868,6 +2881,7 @@ int i3c_master_register(struct i3c_master_controller *master,
 		ret = -ENOMEM;
 		goto err_put_dev;
 	}
+	INIT_WORK(&master->reg_work, i3c_master_reg_work_fn);
 
 	ret = i3c_master_bus_init(master);
 	if (ret)

@@ -2893,12 +2907,15 @@ 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);
 
 	return 0;

@@ -2925,6 +2942,11 @@ void i3c_master_unregister(struct i3c_master_controller *master)
 {
 	i3c_bus_notify(&master->bus, I3C_NOTIFY_BUS_REMOVE);
 
+	i3c_bus_maintenance_lock(&master->bus);
+	master->shutting_down = true;
+	i3c_bus_maintenance_unlock(&master->bus);
+	cancel_work_sync(&master->reg_work);
+
 	i3c_master_i2c_adapter_cleanup(master);
 	i3c_master_unregister_i3c_devs(master);
 	i3c_master_bus_cleanup(master);

include/linux/i3c/master.h +6 -0

index 414a8acde0183..2addb43f85dac 100644
@@ -499,6 +499,7 @@ struct i3c_master_controller_ops {
  * @secondary: true if the master is a secondary master
  * @init_done: true when the bus initialization is done
  * @hotjoin: true if the master support hotjoin
+ * @shutting_down: set to true when master is being unregistered
  * @boardinfo.i3c: list of I3C  boardinfo objects
  * @boardinfo.i2c: list of I2C boardinfo objects
  * @boardinfo: board-level information attached to devices connected on the bus

@@ -508,6 +509,9 @@ struct i3c_master_controller_ops {
  *	in a thread context. Typical examples are Hot Join processing which
  *	requires taking the bus lock in maintenance, which in turn, can only
  *	be done from a sleep-able context
+ * @reg_work: work item used to register newly discovered I3C devices with
+ *	    the driver model, queued to @wq by i3c_master_do_daa() and
+ *	    cancelled when the controller is unregistered
  *
  * A &struct i3c_master_controller has to be registered to the I3C subsystem
  * through i3c_master_register(). None of &struct i3c_master_controller fields

@@ -522,12 +526,14 @@ struct i3c_master_controller {
 	unsigned int secondary : 1;
 	unsigned int init_done : 1;
 	unsigned int hotjoin: 1;
+	bool shutting_down;
 	struct {
 		struct list_head i3c;
 		struct list_head i2c;
 	} boardinfo;
 	struct i3c_bus bus;
 	struct workqueue_struct *wq;
+	struct work_struct reg_work;
 };
 
 /**

Signature · 1 line

2.53.0

Sasha Levin

maintainer

2026-09-10 00:18 UTC #3 lore raw

PATCH 3/3 i3c: master: Fix recursive locking during device registration

In reply to Sasha Levin

From: Adrian Hunter <[email protected]>

[ Upstream commit 456f832e5fc26fbfd3b8200fd4553eee520cc377 ]

For example, with Intel LPSS I3C, LOCKDEP generates a WARNING like:

  # echo intel-lpss-i3c.0 > /sys/bus/platform/drivers/mipi-i3c-hci/unbind
  # echo intel-lpss-i3c.0 > /sys/bus/platform/drivers/mipi-i3c-hci/bind
  WARNING: possible recursive locking detected
  kworker/5:1/94 is trying to acquire lock:
  ffff88811c810d78 (&i3cbus->lock){++++}-{4:4}, at: i3c_device_match_id+0x45/0x370
  but task is already holding lock:
  ffff88811c810d78 (&i3cbus->lock){++++}-{4:4}, at: i3c_master_reg_work_fn+0x21/0x5f0

The local list requires a list node, so add a list node member to struct i3c_device.

Fixes 3a379bbcea0a ("i3c: Add core I3C infrastructure")

Cc [email protected]

Signed-off-by Adrian Hunter <[email protected]>

Reviewed-by Frank Li <[email protected]>

Link https://patch.msgid.link/[email protected] open here

Signed-off-by Alexandre Belloni <[email protected]>

Signed-off-by Sasha Levin <[email protected]>

---
 drivers/i3c/master.c       | 45 ++++++++++++++++++++++++++++----------
 include/linux/i3c/master.h |  3 +++
 2 files changed, 36 insertions(+), 12 deletions(-)

drivers/i3c/master.c +33 ~~-12~~

index 9103dc77a4459..96c29fdaf437a 100644
@@ -1659,12 +1659,21 @@ static int i3c_master_early_i3c_dev_add(struct i3c_master_controller *master,
 static void
 i3c_master_register_new_i3c_devs(struct i3c_master_controller *master)
 {
+	struct i3c_device *i3cdev, *tmp;
 	struct i3c_dev_desc *desc;
+	LIST_HEAD(i3c_unreg_devs);
 	int ret;
 
 	if (!master->init_done)
 		return;
 
+	i3c_bus_maintenance_lock(&master->bus);
+
+	if (master->shutting_down) {
+		i3c_bus_maintenance_unlock(&master->bus);
+		return;
+	}
+
 	i3c_bus_for_each_i3cdev(&master->bus, desc) {
 		if (desc->dev || !desc->info.dyn_addr || desc == master->this)
 			continue;

@@ -1685,25 +1694,37 @@ i3c_master_register_new_i3c_devs(struct i3c_master_controller *master)
 		if (desc->boardinfo)
 			desc->dev->dev.of_node = desc->boardinfo->of_node;
 
-		ret = device_register(&desc->dev->dev);
-		if (ret) {
-			dev_err(&master->dev,
-				"Failed to add I3C device (err = %d)\n", ret);
-			desc->dev->desc = NULL;
-			put_device(&desc->dev->dev);
-			desc->dev = NULL;
-		}
+		list_add_tail(&desc->dev->node, &i3c_unreg_devs);
 	}
+
+	i3c_bus_maintenance_unlock(&master->bus);
+
+	list_for_each_entry_safe(i3cdev, tmp, &i3c_unreg_devs, node) {
+		ret = device_register(&i3cdev->dev);
+		if (ret)
+			dev_err(&master->dev, "Failed to add I3C device (err = %d)\n", ret);
+		else
+			list_del_init(&i3cdev->node);
+	}
+
+	i3c_bus_maintenance_lock(&master->bus);
+
+	list_for_each_entry_safe(i3cdev, tmp, &i3c_unreg_devs, node) {
+		list_del(&i3cdev->node);
+		desc = i3cdev->desc;
+		i3cdev->desc = NULL;
+		put_device(&i3cdev->dev);
+		desc->dev = NULL;
+	}
+
+	i3c_bus_maintenance_unlock(&master->bus);
 }
 
 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_register_new_i3c_devs(master);
 }
 
 /**

include/linux/i3c/master.h +3 -0

index 2addb43f85dac..25efe4757d922 100644
@@ -228,6 +228,8 @@ struct i3c_dev_desc {
  *	  every time the I3C device is rediscovered with a different dynamic
  *	  address assigned
  * @bus: I3C bus this device is attached to
+ * @node: unregistered device list node, only for use by
+ *	  i3c_master_register_new_i3c_devs(), it is not protected by a lock
  *
  * I3C device object exposed to I3C device drivers. The takes care of linking
  * this object to the relevant &struct_i3c_dev_desc one.

@@ -238,6 +240,7 @@ struct i3c_device {
 	struct device dev;
 	struct i3c_dev_desc *desc;
 	struct i3c_bus *bus;
+	struct list_head node;
 };
 
 /*

Signature · 1 line

2.53.0