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 68B282DC32E for ; Wed, 9 Sep 2026 20:50:51 +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=1788987062; cv=none; b=b6XWNhNpWsroy4+VMqTRXszUUMqCYHHlaE5pMfKuOcmshNL7hyPUHapKHNblWthFA3QbrTxFlHyTUa7K227+ID2ibyTSMawSRuhYF7sarrgCoHcsY7KxN0dcWQeZmGdqZgZ9G/qEIeUxCoQ1xUbu+PdrKi7w69aTgIkWsXWcKbk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788987062; c=relaxed/simple; bh=XdTlHssqusNZF02mkffkL5kzzuPIDZm/B14FQt9qt3E=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VFk+gDMF/Hr7Uw8wj+kQ5vLgKbIp3VAGSWG/IVl2hmAgCfXfUBa+pC5of7KFYvnaXdrkd7BKuJnxGyhBspaNS7dxxnq46Ohphh7FCOARK1vhcvLrLK2uFbgRRC2FCUn277DIarARn8YzZxc6MyQlSo6B44ckBbfrVe+xr0m77LQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dnbxn3bR; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="dnbxn3bR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CA7AB1F00898; Wed, 9 Sep 2026 20:50:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788987050; bh=GgFaqUSy6W4NCKcZ46yxPskNv34M5+T+NxGVH0Qix58=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=dnbxn3bR8+n50+xHD7TevJMj8pLba2KlgDni1lyHl65Ts8gPnb6IQ+FWtxjdztrr7 ejaSIIDrfavghysS5TO5epLl8xFLC6T61jc1EdSGGAbsqyGr9PYcDUBjJVCY293qNe +xCpSLMKwRFJWRNcdo71rxE9MFj84hztezW/Cz0RSuiGOKUmZenKk4KmLzQeETLxIS czZvUH4Ffcjbqbx2YWj+BRjBuRaPQmJ8W0gXkp9xarc6gVPKMS7WzGvBl+Rb6Nm0te TaMu0fuDXmnpR/Vg/HiTB5+waujbbHxDKlRpQZY6xzzZeSIwsBqENSKmcmW5nQXjMs P2j8H89OtKALQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Adrian Hunter , Frank Li , Alexandre Belloni , Sasha Levin Subject: [PATCH 6.18.y 2/2] i3c: master: Fix recursive locking during device registration Date: Wed, 9 Sep 2026 16:50:47 -0400 Message-ID: <20260909205047.3699690-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260909205047.3699690-1-sashal@kernel.org> References: <2026090418-debug-slicing-96e1@gregkh> <20260909205047.3699690-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 | 45 ++++++++++++++++++++++++++++---------- include/linux/i3c/master.h | 3 +++ 2 files changed, 36 insertions(+), 12 deletions(-) diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c index 0166490c3da58..e84615a45a1a7 100644 --- a/drivers/i3c/master.c +++ b/drivers/i3c/master.c @@ -1787,12 +1787,21 @@ 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; @@ -1813,25 +1822,37 @@ 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); } /** diff --git a/include/linux/i3c/master.h b/include/linux/i3c/master.h index 1aa1efd835b86..df0132048a102 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