From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.16]) (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 DA7CD336EC0; Thu, 6 Aug 2026 13:19:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.16 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786022364; cv=none; b=kRFasMSDIQquGrtA1igI9Uc2hxV7DM6sYNZHlkoXRSqRzHgWitXh9JFoOTQ3jeVNArPpUSBNCxDuB+gITCbm1o5/qPMHv19s4hEnOKBFQ9Rd/kK14qGOOw6P8OtFIDYyJT7Tto3kvyf2w0KKUFoK4C6s2MvpBJPGHlXnoz/DiG8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786022364; c=relaxed/simple; bh=8qnas1z0yzFN13YNJ/JLjoAtaKWli/KcWEU4XZkGZg4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jsveZx9ELPWbph3rkzacppFTiLSDPjzC0J/8T3IC74tBTQyfJvA1SYMcq4S2kWY7mqOV2aL2O0pmiG2wt37rpvWbpXYwsM8jjbwqGD/mrm4Afo9Xjg4iZPhCYDnZjFedJyR+1PPlJYdIJANAXIh51akyqh+OVF/QTv1r74XTf94= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=lXqWuE9C; arc=none smtp.client-ip=192.198.163.16 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="lXqWuE9C" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1786022360; x=1817558360; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=8qnas1z0yzFN13YNJ/JLjoAtaKWli/KcWEU4XZkGZg4=; b=lXqWuE9COGOAw4UA2n2IuItTXNIiWo9wyOMLHlCkecFxarZ6NLEUHVEU Z+qQucHVKB4XfAT5Dem9ajBj+rFUmUW0VX0ORgbXt1JhM3DsTpML+qSBT VNkLGf6XN5AjvGqV3u8eP+PXurnHvXTnCsagABMzkFk4/gttX6P2O+CR/ Zx6OLTsFtIhtIzuzE43F7YhAMl0fcbOcPDzfoE5l+FACof1MWfjH1S5jn kNnX8mmVgIBMLhyRyi9S3+eBsxw0rN/Tmm9V2UHNzFqw0WPZwn2GgoVlu /sXQ/0fdblGs1mOImBBLXHLIqoNrCL8OpS2FUAmzzzeVIdLfFAt+5DSwh Q==; X-CSE-ConnectionGUID: s2dDDLr+SKuxZW9BJ6q4EQ== X-CSE-MsgGUID: 4mIFs2lTQz2mTKKmOG4KqQ== X-IronPort-AV: E=McAfee;i="6800,10657,11867"; a="74149511" X-IronPort-AV: E=Sophos;i="6.25,208,1779174000"; d="scan'208";a="74149511" Received: from orviesa006.jf.intel.com ([10.64.159.146]) by fmvoesa110.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Aug 2026 06:19:11 -0700 X-CSE-ConnectionGUID: 9ZPlh3lCTs6KcgQ5p0szrg== X-CSE-MsgGUID: vBveXvr1SjOXi5CNKQYXuQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,208,1779174000"; d="scan'208";a="260338057" Received: from mkosciow-mobl1.ger.corp.intel.com (HELO ahunter6-desk) ([10.245.244.200]) by orviesa006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Aug 2026 06:19:08 -0700 From: Adrian Hunter To: alexandre.belloni@bootlin.com Cc: Frank.Li@nxp.com, akhilrajeev@nvidia.com, mukesh.savaliya@oss.qualcomm.com, rafael@kernel.org, linux-i3c@lists.infradead.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-pm@vger.kernel.org Subject: [PATCH V4 01/14] i3c: master: Fix recursive locking during device registration Date: Thu, 6 Aug 2026 16:18:44 +0300 Message-ID: <20260806131857.119830-2-adrian.hunter@intel.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260806131857.119830-1-adrian.hunter@intel.com> References: <20260806131857.119830-1-adrian.hunter@intel.com> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Organization: Intel Finland Oy, Registered Address: c/o Alberga Business Park, 6 krs, Bertel Jungin Aukio 5, 02600 Espoo, Business Identity Code: 0357606 - 4, Domiciled in Helsinki Content-Transfer-Encoding: 8bit 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 --- Changes in V4: Expanded the kernel-doc for the new struct i3c_device @node member to note that it is only for use by i3c_master_register_new_i3c_devs() and is not protected by a lock. Changes in V3: Added Cc: stable@vger.kernel.org Changes in V2: New patch 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 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; }; /* -- 2.53.0