From patchwork Thu Aug 10 15:41:14 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Waiman Long X-Patchwork-Id: 13349657 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 C154AC001E0 for ; Thu, 10 Aug 2023 15:41:58 +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=r5RvlTn2dmznKZ5CuOaN+R/BJzPc+P1o+1pa905fpl4=; b=jsHHaFjdf9XRwS ic1UGmAq7P1JiyzNMtiWblxH2ct4SHCfh5t+opMtuwPA2Dz1eEhPEFGy+qrVcai+8Befrwe+SZVnF WjH5TJn6R2n9xmob6jneLCG4hR02pjvZRZVDtLCAnH7gHRSnf/F7rMEcCtf+0uNCfjoaR5Z4xcw1E LT/dt/38zREnQWw1JfslYS+Io9h0GPOmPpuWDt/88K/zxeDSd+bkQlu4pvmPWUFtYZGzl06IpcKrb yEPtLTXrKi0DkFMhQoQkEOY7zZvIC6FwoW2j1UW3tiJ8BDZV2zuimtbX7lnnQxFhYGMNDZqXBnkRk iPFdCQ19ej/DjzfF06vA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qU7n1-0084RF-1r; Thu, 10 Aug 2023 15:41:31 +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 1qU7my-0084QL-1x for linux-arm-kernel@lists.infradead.org; Thu, 10 Aug 2023 15:41:30 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1691682087; 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=atSIShNb1k5EouTCC7gYCjFuXMvvzMrZitLjweZI368=; b=P7buExrgleMf10moYUOZVV0ltdu4DCoQwNDvhMKRrA8Sh9yNzxn2XX3zUfwqBnywJC+7BQ BD6K0ODsix4loew3ZZTmsjmycVcJ/v4yP+b8RxvaQ7dK47p+0xcYAi1ipQKlVGBO7EM7Ju JDiL7uhWVb1zQulpN7yTaaL1l9mHMXU= Received: from mimecast-mx02.redhat.com (66.187.233.73 [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-320-qUnfye_xObiUAg9FNFPnAg-1; Thu, 10 Aug 2023 11:41:24 -0400 X-MC-Unique: qUnfye_xObiUAg9FNFPnAg-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 6AFCB381C16D; Thu, 10 Aug 2023 15:41:22 +0000 (UTC) Received: from llong.com (unknown [10.22.18.33]) by smtp.corp.redhat.com (Postfix) with ESMTP id F33B72026D4B; Thu, 10 Aug 2023 15:41:21 +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 v5] perf/arm-dmc620: Fix dmc620_pmu_irqs_lock/cpu_hotplug_lock circular lock dependency Date: Thu, 10 Aug 2023 11:41:14 -0400 Message-Id: <20230810154114.405742-1-longman@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230810_084128_712069_760F4FAE X-CRM114-Status: GOOD ( 18.81 ) 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() calls cpuhp_state_add_instance_nocalls(). Since dmc620_pmu_irqs_lock is used for protecting the dmc620_pmu_irqs structure, 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 adding a new dmc620_pmu_get_lock for protecting the call to __dmc620_pmu_get_irq(). While at it, rename dmc620_pmu_irqs_lock to dmc620_pmu_list_lock as it is now just protecting the iteration and modification of pmus_node and irqs_node lists. As a result, cpuhp_state_add_instance_nocalls() won't be called with reanemd dmc620_pmu_list_lock held and cpu_hotplug_lock won't be acquired after dmc620_pmu_list_lock. Suggested-by: Robin Murphy Signed-off-by: Waiman Long --- drivers/perf/arm_dmc620_pmu.c | 34 ++++++++++++++++++++++------------ 1 file changed, 22 insertions(+), 12 deletions(-) diff --git a/drivers/perf/arm_dmc620_pmu.c b/drivers/perf/arm_dmc620_pmu.c index 9d0f01c4455a..a5bfc8f2e6ab 100644 --- a/drivers/perf/arm_dmc620_pmu.c +++ b/drivers/perf/arm_dmc620_pmu.c @@ -66,8 +66,14 @@ #define DMC620_PMU_COUNTERn_OFFSET(n) \ (DMC620_PMU_COUNTERS_BASE + 0x28 * (n)) +/* + * The allowable lock ordering is: + * - dmc620_pmu_get_lock (protects call to __dmc620_pmu_get_irq()) + * - dmc620_pmu_list_lock (protects pmus_node & irqs_node lists) + */ +static DEFINE_MUTEX(dmc620_pmu_get_lock); +static DEFINE_MUTEX(dmc620_pmu_list_lock); static LIST_HEAD(dmc620_pmu_irqs); -static DEFINE_MUTEX(dmc620_pmu_irqs_lock); struct dmc620_pmu_irq { struct hlist_node node; @@ -423,9 +429,11 @@ static struct dmc620_pmu_irq *__dmc620_pmu_get_irq(int irq_num) struct dmc620_pmu_irq *irq; int ret; + mutex_lock(&dmc620_pmu_list_lock); 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 unlock_out; + mutex_unlock(&dmc620_pmu_list_lock); irq = kzalloc(sizeof(*irq), GFP_KERNEL); if (!irq) @@ -452,8 +460,10 @@ 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_list_lock); list_add(&irq->irqs_node, &dmc620_pmu_irqs); - +unlock_out: + mutex_unlock(&dmc620_pmu_list_lock); return irq; out_free_irq: @@ -467,17 +477,17 @@ static int dmc620_pmu_get_irq(struct dmc620_pmu *dmc620_pmu, int irq_num) { struct dmc620_pmu_irq *irq; - mutex_lock(&dmc620_pmu_irqs_lock); + mutex_lock(&dmc620_pmu_get_lock); irq = __dmc620_pmu_get_irq(irq_num); - mutex_unlock(&dmc620_pmu_irqs_lock); + mutex_unlock(&dmc620_pmu_get_lock); if (IS_ERR(irq)) return PTR_ERR(irq); dmc620_pmu->irq = irq; - mutex_lock(&dmc620_pmu_irqs_lock); + mutex_lock(&dmc620_pmu_list_lock); list_add_rcu(&dmc620_pmu->pmus_node, &irq->pmus_node); - mutex_unlock(&dmc620_pmu_irqs_lock); + mutex_unlock(&dmc620_pmu_list_lock); return 0; } @@ -486,16 +496,16 @@ static void dmc620_pmu_put_irq(struct dmc620_pmu *dmc620_pmu) { struct dmc620_pmu_irq *irq = dmc620_pmu->irq; - mutex_lock(&dmc620_pmu_irqs_lock); + mutex_lock(&dmc620_pmu_list_lock); list_del_rcu(&dmc620_pmu->pmus_node); if (!refcount_dec_and_test(&irq->refcount)) { - mutex_unlock(&dmc620_pmu_irqs_lock); + mutex_unlock(&dmc620_pmu_list_lock); return; } list_del(&irq->irqs_node); - mutex_unlock(&dmc620_pmu_irqs_lock); + mutex_unlock(&dmc620_pmu_list_lock); free_irq(irq->irq_num, irq); cpuhp_state_remove_instance_nocalls(cpuhp_state_num, &irq->node); @@ -638,10 +648,10 @@ static int dmc620_pmu_cpu_teardown(unsigned int cpu, return 0; /* We're only reading, but this isn't the place to be involving RCU */ - mutex_lock(&dmc620_pmu_irqs_lock); + mutex_lock(&dmc620_pmu_list_lock); list_for_each_entry(dmc620_pmu, &irq->pmus_node, pmus_node) perf_pmu_migrate_context(&dmc620_pmu->pmu, irq->cpu, target); - mutex_unlock(&dmc620_pmu_irqs_lock); + mutex_unlock(&dmc620_pmu_list_lock); WARN_ON(irq_set_affinity(irq->irq_num, cpumask_of(target))); irq->cpu = target;