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 96FCC37F33A for ; Fri, 4 Sep 2026 04:37:54 +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=1788496676; cv=none; b=JGkF9tRbKEn5FDv/Dma0uo22IrLmGOewjq/Ul2ROE7FAsl9HbQTBrd1E5MqUhmp6pjEHQR9N9uoZ2A9XR2nMXdaeK43APRPgJwpQ9loheCQQTo7zbHEG9Uqbj3r8A7O0c1wpVZvMm5CnwwLYFI8P351bzSWb9m1HPHgTjmrYaaM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788496676; c=relaxed/simple; bh=xi3rQKewuUpRnTkWW/8BqAV5DpXypgqtzTqkHcQhIuk=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=Va5vn8NCcwnZxejdJnW1gzcBFdyrB74Ef7MUSLK9h6HXSTBjV5h8dIbH/zQVANAW0Rf5lQMTY5XzTFInhQZwS9IhENtYlTjgirhXNIkiRw+YbF2jV0Mu3QPGcXTl8dkDvw64ue0OwUouIVy+EEgc5sEFTt90+kwxA31M+K94rpk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=dSKDxtA0; 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="dSKDxtA0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F28BB1F00A3D; Fri, 4 Sep 2026 04:37:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788496674; bh=pFXuPtADq9y4K/0UCRy8204UWteigKNp/vP/hPmssfk=; h=Subject:To:Cc:From:Date; b=dSKDxtA0dtomPxgJBvtQqXLpF+U968mRmXi0pqkqOS15sK6reO85r5fXoAiN77Iwm xzGgOlyBIianmlgmIbxEYTUhMl3hS9F5bbq4Lkz6eXs62pO384kFfk8WTdCIIp5vtA xS559UT1xXGRlaBGNDFI1+d5I/KZ546w472Zxn4E= Subject: FAILED: patch "[PATCH] i3c: master: Fix recursive locking during device registration" failed to apply to 6.1-stable tree To: adrian.hunter@intel.com,Frank.Li@nxp.com,alexandre.belloni@bootlin.com Cc: From: Date: Fri, 04 Sep 2026 06:37:20 +0200 Message-ID: <2026090420-phobia-unluckily-1be7@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.1-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 . 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-6.1.y git checkout FETCH_HEAD git cherry-pick -x 456f832e5fc26fbfd3b8200fd4553eee520cc377 # git commit -s git send-email --to '' --in-reply-to '2026090420-phobia-unluckily-1be7@gregkh' --subject-prefix 'PATCH 6.1.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 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: 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 diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c index f485b98805cf..d2fb1a110521 100644 --- a/drivers/i3c/master.c +++ b/drivers/i3c/master.c @@ -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); } /** diff --git a/include/linux/i3c/master.h b/include/linux/i3c/master.h index 2dc139a217bf..26535beb1e77 100644 --- a/include/linux/i3c/master.h +++ b/include/linux/i3c/master.h @@ -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; }; /*