From patchwork Mon Jul 10 18:19:59 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Waiman Long X-Patchwork-Id: 13307476 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 0B612EB64D9 for ; Mon, 10 Jul 2023 18:20:48 +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=DX5SFFg5erClMHxGQqBm82y2CRvxAlVBWmS3ryx5ask=; b=YNwg1KRxEVjSnz WSHqRgnYrvCIPp6v8rqn6czuRQKWtoEWuCEbgrbqNg6H6b+xgcrTI8zWNMn6WOLX64Wo1gFGIa7am wEiXcgM3qfA+0wyd+oxAlJv/8W2QxKnh3pepuPz8hl+/zLJO7HmVkF9Qr5ObNvico9/qCa/pctaMo cEJV2VRWKIMNziMlgQdVBIof3amL28u2Zq7lY7L4TqXOu2UIuNWhnCj3lBVT1tm8QW4+BQ8YcDoz5 o6fb6d5LPQ+JjW68r1W9M2G872H9aDe+KqScZ8EQaxjcEh/XPc/tbltB1urxeM0+jfboaL7moqfJJ QZ+N3ZvTHgEdr33O4aOg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qIvUe-00CRbC-2d; Mon, 10 Jul 2023 18:20:16 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qIvUb-00CRZf-2h for linux-arm-kernel@lists.infradead.org; Mon, 10 Jul 2023 18:20:15 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1689013210; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=Nv5fweDCngTesnKRLAb8mrwCNzQpSKJUun6VW1O8oHw=; b=NnAHbJDgSEQXiasDGn1JntmAKldr4QyAnGqWWoCHgnUadrG/3FidsXPDfe3ffK6q9qmtvG hC83/tJuubbddyMtercrG5rb91mNmg5bAAXsvu2NFtMasAmR2xupeDiCbH5PvtxcMBd3lL lwYa1YGvKMwIfkC6JIiFXRxq9jTmO44= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-58-2YG5B3anO1epJciQrdsgsA-1; Mon, 10 Jul 2023 14:20:06 -0400 X-MC-Unique: 2YG5B3anO1epJciQrdsgsA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 74BCB1044589; Mon, 10 Jul 2023 18:20:06 +0000 (UTC) Received: from llong.com (unknown [10.22.33.187]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1974F40C6CD1; Mon, 10 Jul 2023 18:20:06 +0000 (UTC) From: Waiman Long To: Will Deacon , Mark Rutland Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Robin Murphy , Waiman Long Subject: [PATCH v2] perf/arm-dmc620: Reverse locking order in dmc620_pmu_get_irq() Date: Mon, 10 Jul 2023 14:19:59 -0400 Message-Id: <20230710181959.2750269-1-longman@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230710_112013_959631_86A9684D X-CRM114-Status: GOOD ( 17.05 ) 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 The following circular locking dependency was reported when running cpus online/offline test on an arm64 system. [ 84.195923] Chain exists of: dmc620_pmu_irqs_lock --> cpu_hotplug_lock --> cpuhp_state-down [ 84.207305] Possible unsafe locking scenario: [ 84.213212] CPU0 CPU1 [ 84.217729] ---- ---- [ 84.222247] lock(cpuhp_state-down); [ 84.225899] lock(cpu_hotplug_lock); [ 84.232068] lock(cpuhp_state-down); [ 84.238237] lock(dmc620_pmu_irqs_lock); [ 84.242236] *** DEADLOCK *** The problematic locking order seems to be lock(dmc620_pmu_irqs_lock) --> lock(cpu_hotplug_lock) This locking order happens when dmc620_pmu_get_irq() is called from dmc620_pmu_device_probe(). Since dmc620_pmu_irqs_lock is used for protecting the dmc620_pmu_irqs structure only, we don't actually need to hold the lock when adding a new instance to the CPU hotplug subsystem. Fix this possible deadlock scenario by releasing the lock when a new dmc620_pmu_irq needs to be created and reacquring it again when the new irq is inserted into dmc620_pmu_irqs. Suggested-by: Robin Murphy Signed-off-by: Waiman Long --- drivers/perf/arm_dmc620_pmu.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/perf/arm_dmc620_pmu.c b/drivers/perf/arm_dmc620_pmu.c index 9d0f01c4455a..dbf67c122420 100644 --- a/drivers/perf/arm_dmc620_pmu.c +++ b/drivers/perf/arm_dmc620_pmu.c @@ -419,13 +419,16 @@ static irqreturn_t dmc620_pmu_handle_irq(int irq_num, void *data) } static struct dmc620_pmu_irq *__dmc620_pmu_get_irq(int irq_num) + __releases(&dmc620_pmu_irqs_lock) { struct dmc620_pmu_irq *irq; int ret; list_for_each_entry(irq, &dmc620_pmu_irqs, irqs_node) if (irq->irq_num == irq_num && refcount_inc_not_zero(&irq->refcount)) - return irq; + goto out_unlock; + + mutex_unlock(&dmc620_pmu_irqs_lock); irq = kzalloc(sizeof(*irq), GFP_KERNEL); if (!irq) @@ -452,8 +455,12 @@ static struct dmc620_pmu_irq *__dmc620_pmu_get_irq(int irq_num) goto out_free_irq; irq->irq_num = irq_num; + + mutex_lock(&dmc620_pmu_irqs_lock); list_add(&irq->irqs_node, &dmc620_pmu_irqs); +out_unlock: + mutex_unlock(&dmc620_pmu_irqs_lock); return irq; out_free_irq: @@ -469,7 +476,7 @@ static int dmc620_pmu_get_irq(struct dmc620_pmu *dmc620_pmu, int irq_num) mutex_lock(&dmc620_pmu_irqs_lock); irq = __dmc620_pmu_get_irq(irq_num); - mutex_unlock(&dmc620_pmu_irqs_lock); + /* mutex_unlock() called inside __dmc620_pmu_get_irq() */ if (IS_ERR(irq)) return PTR_ERR(irq);