From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 267F3C5ACC2 for ; Fri, 7 Aug 2026 14:57:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=WTHnkrrwlx/xrbXg7+fT96hEvIpVMQXzsyPl+PIJtn0=; b=OMefgka6kfwD9L GY9ufVL6UEkX4yDcTpO9G4TwLON7WTYKIqXp+NhxnSA6mIXJkl6/3g6AmEYgG1oNOuMDZggGsBL/1 2Os2MKQvGMHlpfSyyXOA2weBd4vuvaFkxmX8Gx8OvG8EzmkpuNMH48uWssJqcsQOPKXMbPSdzRUAD Z8FRBUfCuNd0A6NOky5GkYXsaQA2x7uzHF2IYAmoS1WWfty81YuPTeIlrAW1l/vZhHxHGRjZLP5EJ oZUN+cCsapTY3uuzdXrjYAlCl17F4JbcynZQ6Kzbm4GY48TVCOgRlvpprTXGC5/BQx3mSDmItDFKy 1n3k+S/S8sMXWS3o8XLQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wsM0p-00000008Ihc-2pRu; Fri, 07 Aug 2026 14:57:31 +0000 Received: from mgamail.intel.com ([198.175.65.20]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wsM0m-00000008Ifs-46e7 for linux-i3c@lists.infradead.org; Fri, 07 Aug 2026 14:57:30 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1786114649; x=1817650649; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=iUf7XrtbaGTZLGwnhEqDqVPZQrqJ/bjk10K3AhMjNNw=; b=P5unf9xJ/WRJFZTWK8wPkgLQ6ZuEXmr1V57RPi9XzmXisrtQB4FqgYuc SVSCfLPPDEHD4/rRmmXgZ9KKpE2dbWkd9lKF+7p6day1DXIPRfBOMxB+r 6POmPLXFqwcfM+VW0p/SATGUrp79IOhhTJ9bW8JhKDUgaithcWfz0Rx9Z A4Ase+bpqr/TMCfdkAlah84MMKgJm28cCWSGJBGx0khFNqqTBW2oW4WpK lq9Gdz1/DqtWnYtW9CvEQImsJLTJiNZaDnr/9OmkgUVy5bS6TVwwu2hS9 aHz7l0Xtf8rIWE7L2A7ZPNe7+7raAMbT1867ZLs6dWtwNqZY06NqlOZgp A==; X-CSE-ConnectionGUID: 3oct6LiyR82GDtL/nAJQMg== X-CSE-MsgGUID: CCF5AK8cSKqewXKPg7o+HQ== X-IronPort-AV: E=McAfee;i="6800,10657,11868"; a="86485180" X-IronPort-AV: E=Sophos;i="6.25,210,1779174000"; d="scan'208";a="86485180" Received: from fmviesa008.fm.intel.com ([10.60.135.148]) by orvoesa112.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Aug 2026 07:57:24 -0700 X-CSE-ConnectionGUID: MiaaZ06gQ6KmppPlDM5SPg== X-CSE-MsgGUID: M0Ah3gm0RiSsebDU/Co6Qg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,210,1779174000"; d="scan'208";a="259809875" Received: from amilburn-desk.amilburn-desk (HELO ahunter6-desk) ([10.245.245.114]) by fmviesa008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Aug 2026 07:56:48 -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 V5 01/14] i3c: master: Fix recursive locking during device registration Date: Fri, 7 Aug 2026 17:56:25 +0300 Message-ID: <20260807145638.168865-2-adrian.hunter@intel.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260807145638.168865-1-adrian.hunter@intel.com> References: <20260807145638.168865-1-adrian.hunter@intel.com> 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260807_075729_062256_803E1299 X-CRM114-Status: GOOD ( 19.37 ) X-BeenThere: linux-i3c@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-i3c" Errors-To: linux-i3c-bounces+linux-i3c=archiver.kernel.org@lists.infradead.org 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 --- Changes in V5: Added Frank's Rev'd-by 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 -- linux-i3c mailing list linux-i3c@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-i3c