From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A0812381E98; Sat, 12 Sep 2026 09:33:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789205594; cv=none; b=SngGCyz5lUyZ+urSQloeIb3cWaaoy3nkBAPAwXX3LNV+jcXc5hCvQomfeSLFjysuRi4gl7G+BoaeYhYjcjXcdu5GDz6mX4ii5GK176rIexK65Csu1P8bcObagu+Rn0sgyl2Gf3exCQ8I3XGzgdKDSPrXWxsw2Th+RnauI76BSAw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789205594; c=relaxed/simple; bh=WVlSY0UuUCU9dZ6sRKtoTVMneZKhhsNcnrwOaO+pgZA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VYtdIEIl8lxXu55CV9HiFGA5ijLlmBWn7y5CgdxVUISDFirEKd0XCiHXtGh6CXhE/TU6NGb8+FJWqy59skKzUGhJ708K48ezpIhI5baMHCdefVvU1Jr8Ed7EqYc8vF9uNjhMCUSukkB95uhalJCle1MEAlq5JJiPV8TINueAzDc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ui1DrzF9; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="ui1DrzF9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C5E661F000FF; Sat, 12 Sep 2026 09:33:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789205589; bh=UFx9ZrlOa7MpYYKt4ox5CkrXiZs/5hMzQ+7DgiuC1Bc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ui1DrzF9fs3ahsMucOvPINVJDspWV8lJaeG91PPOTZQbD9jJB8do3B7PvLT7B5WAm 34vvbWEkO65E57h5KMaR5UCtjefhCcEYtOE+gm/LXNDhJ5FT2toJ6qiJ5wL3sAaQYM jqrgJ3p7K1L8xAksFLOfEnQCq1hJ7kS1XMSY9aRg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Adrian Hunter , Frank Li , Alexandre Belloni , Sasha Levin Subject: [PATCH 6.18 0032/1518] i3c: master: Fix recursive locking during device registration Date: Sat, 12 Sep 2026 08:36:41 +0200 Message-ID: <20260912065624.151359248@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065623.398859879@linuxfoundation.org> References: <20260912065623.398859879@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Adrian Hunter [ Upstream commit 456f832e5fc26fbfd3b8200fd4553eee520cc377 ] 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: stable@vger.kernel.org Signed-off-by: Adrian Hunter Reviewed-by: Frank Li Link: https://patch.msgid.link/20260807145638.168865-2-adrian.hunter@intel.com Signed-off-by: Alexandre Belloni Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/i3c/master.c | 45 +++++++++++++++++++++++++++++++++------------ include/linux/i3c/master.h | 3 +++ 2 files changed, 36 insertions(+), 12 deletions(-) --- a/drivers/i3c/master.c +++ b/drivers/i3c/master.c @@ -1787,12 +1787,21 @@ err_free_dev: 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; @@ -1813,25 +1822,37 @@ i3c_master_register_new_i3c_devs(struct 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); } /** --- a/include/linux/i3c/master.h +++ b/include/linux/i3c/master.h @@ -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; }; /*