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 4B1003C7E1D; Sat, 17 Oct 2026 16:46:01 +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=1792255562; cv=none; b=LVZbumcuP/RZjUrDp8toKA6+oH2Sxr2ZyBXEREi+0Zx6cXCyitR7pGEBDlv595MUNn8UIfXrZKKTF6B0EMWFDsLQzN0BpAWH21Fv2vpcWaN+hNCuYble0nLQ5SWyBTO763dv5c3WBzQL0Hw0pSR25LgBkFbBrn6Ik0Ag1K7Zg6I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792255562; c=relaxed/simple; bh=hqWU/vloKjS03gMAoWlwoK/L1y2C6SgXSuEbPfxzQE4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=s8HVvqTZAYVW8kczHAyu6GGqGszmv1UZSHlCXw45kcHwgFeRYJRGMhmNpccbinIUhAPfweNwXRYFH6Wkvgo7zZLr0/AKbRTn0ISIFtIgpl1axUUNixNDHrj2w12o70+7GSo9zLN7EJYV/w0gqVKRqBLgGaK2Ejqz3WCDfVc5PF8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=evj0ll8p; 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="evj0ll8p" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A412B1F000C7; Sat, 17 Oct 2026 16:46:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1792255561; bh=S26IWwn3OOtrde4xddvRjr3v0UMboDuhYwT+VgdNh8A=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=evj0ll8pm2UDhZFdcigZtjEOyeJwhiHLZhPwmz96Mh0hUn+Y2YMODdk9R8MLm74dA SfvaTnGqAlM3UJkMcaCqRPQxKwvNuFLlOqpDD9Ir14fMBPK5D2fdE3biO1u6wmPV3N LwoOaDryMflXqaI+T5+WdBcT7dHAWQjmFwAlgVXc= 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 6.12 817/869] i3c: master: Fix recursive locking during device registration Date: Sat, 17 Oct 2026 18:00:58 +0200 Message-ID: <20261017160057.838156916@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261017160036.979869304@linuxfoundation.org> References: <20261017160036.979869304@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 6.12-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 --- drivers/i3c/master.c | 39 ++++++++++++++++++++++++++------------ include/linux/i3c/master.h | 3 +++ 2 files changed, 30 insertions(+), 12 deletions(-) diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c index 4b23fe33329b0..bb15b621c067b 100644 --- a/drivers/i3c/master.c +++ b/drivers/i3c/master.c @@ -1661,12 +1661,16 @@ 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); + i3c_bus_for_each_i3cdev(&master->bus, desc) { if (desc->dev || !desc->info.dyn_addr || desc == master->this) continue; @@ -1687,15 +1691,30 @@ 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); } /** @@ -1724,9 +1743,7 @@ int i3c_master_do_daa(struct i3c_master_controller *master) if (ret) return ret; - i3c_bus_normaluse_lock(&master->bus); i3c_master_register_new_i3c_devs(master); - i3c_bus_normaluse_unlock(&master->bus); return 0; } @@ -2904,9 +2921,7 @@ int i3c_master_register(struct i3c_master_controller *master, * register I3C devices discovered during the initial DAA. */ master->init_done = true; - i3c_bus_normaluse_lock(&master->bus); i3c_master_register_new_i3c_devs(master); - i3c_bus_normaluse_unlock(&master->bus); return 0; diff --git a/include/linux/i3c/master.h b/include/linux/i3c/master.h index 414a8acde0183..a17433c2458a3 100644 --- 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; }; /* -- 2.53.0