From patchwork Thu Jul 21 13:03:29 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sudeep Holla X-Patchwork-Id: 12925110 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 48EB5C43334 for ; Thu, 21 Jul 2022 13:14:13 +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: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:In-Reply-To:References: List-Owner; bh=6MkcidDn9rd06i+5gqOFtapw3dd5mBkthtWfyiEvy8c=; b=DJ1zmkgYGWCh1N ot8/N41FYW+aikVAjzlbIEW/Gl1FKukwDGJVP4pF+cHGFZDPfGuDKEDEvQK7BIlEyiNQKlRHUMpZr U606mWthgqfQGU0jlK0TArNP1Jv/7LW/q88lfXO4NYRDc52L+fdKPujWlTskDIm+zAsR/bfljL1ru ii4VyFoSkCJ3NNDlNO0HUTIydIune2ozX2lcU2B+XxICc8Pw+Obk1H/ySOmrxqTzNJLGOtU+NpyO2 CPdqtwIiIdih42KyZK/lUUIkmE4HhRI1uilSsrqY9+tZMmBlaTmr2sm+8zvNnxMBinPOW5B4oYDaM J6XKJ4ic6Xw05emJaQDw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oEVz5-006pRP-Pq; Thu, 21 Jul 2022 13:12:56 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oEVqF-006XR3-Im for linux-arm-kernel@lists.infradead.org; Thu, 21 Jul 2022 13:03:49 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 5F7AF23A; Thu, 21 Jul 2022 06:03:40 -0700 (PDT) Received: from usa.arm.com (e103737-lin.cambridge.arm.com [10.1.197.49]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id D37D73F73D; Thu, 21 Jul 2022 06:03:38 -0700 (PDT) From: Sudeep Holla To: linux-arm-kernel@lists.infradead.org Cc: Sudeep Holla , coresight@lists.linaro.org, Mathieu Poirier , Suzuki K Poulose , Mike Leach , Leo Yan Subject: [PATCH] coresight: Fix possible deadlock with lock dependency Date: Thu, 21 Jul 2022 14:03:29 +0100 Message-Id: <20220721130329.3787211-1-sudeep.holla@arm.com> X-Mailer: git-send-email 2.37.1 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220721_060347_773928_7CC07938 X-CRM114-Status: GOOD ( 14.94 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org With lockdeps enabled, we get the following warning: ====================================================== WARNING: possible circular locking dependency detected ------------------------------------------------------ kworker/u12:1/53 is trying to acquire lock: ffff80000adce220 (coresight_mutex){+.+.}-{4:4}, at: coresight_set_assoc_ectdev_mutex+0x3c/0x5c but task is already holding lock: ffff80000add1f60 (ect_mutex){+.+.}-{4:4}, at: cti_probe+0x318/0x394 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (ect_mutex){+.+.}-{4:4}: __mutex_lock_common+0xd8/0xe60 mutex_lock_nested+0x44/0x50 cti_add_assoc_to_csdev+0x4c/0x184 coresight_register+0x2f0/0x314 tmc_probe+0x33c/0x414 -> #0 (coresight_mutex){+.+.}-{4:4}: __lock_acquire+0x1a20/0x32d0 lock_acquire+0x160/0x308 __mutex_lock_common+0xd8/0xe60 mutex_lock_nested+0x44/0x50 coresight_set_assoc_ectdev_mutex+0x3c/0x5c cti_update_conn_xrefs+0x6c/0xf8 cti_probe+0x33c/0x394 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(ect_mutex); lock(coresight_mutex); lock(ect_mutex); lock(coresight_mutex); *** DEADLOCK *** 4 locks held by kworker/u12:1/53: #0: ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x1fc/0x63c #1: (deferred_probe_work){+.+.}-{0:0}, at: process_one_work+0x228/0x63c #2: (&dev->mutex){....}-{4:4}, at: __device_attach+0x48/0x1a8 #3: (ect_mutex){+.+.}-{4:4}, at: cti_probe+0x318/0x394 To fix the same, call cti_add_assoc_to_csdev without the holding coresight_mutex and confine the locking while setting the associated ect / cti device using coresight_set_assoc_ectdev_mutex(). Cc: Mathieu Poirier Cc: Suzuki K Poulose Cc: Mike Leach Cc: Leo Yan Signed-off-by: Sudeep Holla Reviewed-by: Mike Leach --- drivers/hwtracing/coresight/coresight-core.c | 7 ++++--- drivers/hwtracing/coresight/coresight-cti-core.c | 5 +++-- 2 files changed, 7 insertions(+), 5 deletions(-) Hi, I am not sure if I missed to consider something, but this is something I think could be the fix. Regards, Sudeep diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c index 1edfec1e9d18..275b4dce8401 100644 --- a/drivers/hwtracing/coresight/coresight-core.c +++ b/drivers/hwtracing/coresight/coresight-core.c @@ -1659,14 +1659,15 @@ struct coresight_device *coresight_register(struct coresight_desc *desc) ret = coresight_fixup_device_conns(csdev); if (!ret) ret = coresight_fixup_orphan_conns(csdev); - if (!ret && cti_assoc_ops && cti_assoc_ops->add) - cti_assoc_ops->add(csdev); out_unlock: mutex_unlock(&coresight_mutex); /* Success */ - if (!ret) + if (!ret) { + if (cti_assoc_ops && cti_assoc_ops->add) + cti_assoc_ops->add(csdev); return csdev; + } /* Unregister the device if needed */ if (registered) { diff --git a/drivers/hwtracing/coresight/coresight-cti-core.c b/drivers/hwtracing/coresight/coresight-cti-core.c index 8988b2ed2ea6..1be92342b5b9 100644 --- a/drivers/hwtracing/coresight/coresight-cti-core.c +++ b/drivers/hwtracing/coresight/coresight-cti-core.c @@ -541,7 +541,7 @@ cti_match_fixup_csdev(struct cti_device *ctidev, const char *node_name, /* * Search the cti list to add an associated CTI into the supplied CS device * This will set the association if CTI declared before the CS device. - * (called from coresight_register() with coresight_mutex locked). + * (called from coresight_register() without coresight_mutex locked). */ static void cti_add_assoc_to_csdev(struct coresight_device *csdev) { @@ -569,7 +569,8 @@ static void cti_add_assoc_to_csdev(struct coresight_device *csdev) * if we found a matching csdev then update the ECT * association pointer for the device with this CTI. */ - csdev->ect_dev = ect_item->csdev; + coresight_set_assoc_ectdev_mutex(csdev->ect_dev, + ect_item->csdev); break; } }