From patchwork Wed Apr 5 17:28:42 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Waiman Long X-Patchwork-Id: 13202318 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 5EF13C76188 for ; Wed, 5 Apr 2023 17:29:46 +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=yVxFIc51h+rOeG23CqA3nYwoeAUvPkUx1q/mGFfz+nY=; b=10juKixKp1UxZt Qye0OcQh5GG2+Htg1XpR3yeyHOxbPylmBISz4V0X3ImWpzs12+GRU4Cr9CwcehTagRMuuEDTHfAAu 8CvUttzDvoT58vMLQt6Tvr/KoOuhKiDv+dortJpilgoTSz+pOhxZPPfYpVNAWXrI9Z6PJynHBODtt M4aS9RNdDvpTQOoZxZQs0iBNfOMRHlWYyp8rh3wsc9dLcHxud2A+tBI8fg6pIzTpN0rS7KRWnkMx/ 1LJF9yBhmr+k8XtrwlpXdQ56zZMbCmFcldV1rRo3l2Fn1Tw/P8lgVzrMsjbkLGC5tMn91kLg7Q/ha KxI/s2VDzTCwwmIobZuA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1pk6wK-005Gdb-04; Wed, 05 Apr 2023 17:28:56 +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 1pk6wG-005Gcz-26 for linux-arm-kernel@lists.infradead.org; Wed, 05 Apr 2023 17:28:53 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1680715731; 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=GPqtHGUUdaGMWj+r62KgPaCWtTqZFGGxhe2WBH2SAZQ=; b=dKfPiQA6BAAutZCGHfi9HFDycnmnIzn1N6UINI8LZ0W0HZ1W0IPU0l7ZkakqacGgSCkd2o KTqBKi6NXVj1Ie9uDJJ+JuX09aD2Pwe6Z2dMaK7jg/cqsrtKFMSOC1nPfPkMiDe68NsG3V cZHMmszg0r3CT1PtY5moSUj1+SQeTog= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-616-qymVOFufN7GrAuaKToXmBQ-1; Wed, 05 Apr 2023 13:28:49 -0400 X-MC-Unique: qymVOFufN7GrAuaKToXmBQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 43936381458A; Wed, 5 Apr 2023 17:28:49 +0000 (UTC) Received: from llong.com (dhcp-17-153.bos.redhat.com [10.18.17.153]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0C647C1602A; Wed, 5 Apr 2023 17:28:49 +0000 (UTC) From: Waiman Long To: Will Deacon , Mark Rutland Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Waiman Long Subject: [PATCH] perf/arm-dmc620: Reverse locking order in dmc620_pmu_get_irq() Date: Wed, 5 Apr 2023 13:28:42 -0400 Message-Id: <20230405172842.2663770-1-longman@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230405_102852_764710_36118F0C X-CRM114-Status: GOOD ( 14.79 ) 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(). Fix this possible deadlock scenario by reversing the locking order. Also export __cpuhp_state_add_instance_cpuslocked() so that it can be accessed by kernel modules. Signed-off-by: Waiman Long --- drivers/perf/arm_dmc620_pmu.c | 4 +++- kernel/cpu.c | 1 + 2 files changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/perf/arm_dmc620_pmu.c b/drivers/perf/arm_dmc620_pmu.c index 54aa4658fb36..78d3bfbe96a6 100644 --- a/drivers/perf/arm_dmc620_pmu.c +++ b/drivers/perf/arm_dmc620_pmu.c @@ -425,7 +425,7 @@ static struct dmc620_pmu_irq *__dmc620_pmu_get_irq(int irq_num) if (ret) goto out_free_irq; - ret = cpuhp_state_add_instance_nocalls(cpuhp_state_num, &irq->node); + ret = cpuhp_state_add_instance_nocalls_cpuslocked(cpuhp_state_num, &irq->node); if (ret) goto out_free_irq; @@ -445,9 +445,11 @@ static int dmc620_pmu_get_irq(struct dmc620_pmu *dmc620_pmu, int irq_num) { struct dmc620_pmu_irq *irq; + cpus_read_lock(); mutex_lock(&dmc620_pmu_irqs_lock); irq = __dmc620_pmu_get_irq(irq_num); mutex_unlock(&dmc620_pmu_irqs_lock); + cpus_read_unlock(); if (IS_ERR(irq)) return PTR_ERR(irq); diff --git a/kernel/cpu.c b/kernel/cpu.c index 6c0a92ca6bb5..05daaef362e6 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -2036,6 +2036,7 @@ int __cpuhp_state_add_instance_cpuslocked(enum cpuhp_state state, mutex_unlock(&cpuhp_state_mutex); return ret; } +EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance_cpuslocked); int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node, bool invoke)