From patchwork Thu May 4 11:35:08 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: AngeloGioacchino Del Regno X-Patchwork-Id: 13231061 X-Patchwork-Delegate: kw@linux.com 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7A5A4C77B7C for ; Thu, 4 May 2023 11:35:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230017AbjEDLfV (ORCPT ); Thu, 4 May 2023 07:35:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51756 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229872AbjEDLfU (ORCPT ); Thu, 4 May 2023 07:35:20 -0400 Received: from madras.collabora.co.uk (madras.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e5ab]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DF15F44B5; Thu, 4 May 2023 04:35:18 -0700 (PDT) Received: from IcarusMOD.eternityproject.eu (unknown [IPv6:2001:b07:2ed:14ed:c5f8:7372:f042:90a2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: kholk11) by madras.collabora.co.uk (Postfix) with ESMTPSA id 981BD66032D1; Thu, 4 May 2023 12:35:16 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1683200117; bh=oYDe/VXfJGa+IBEXNZZL8Wjnx24xldbrD++GRNp7wf8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SSY9a5QIjnOdxPA/nZt/sT2nUHh81bauNVLFJmH9cSX+HGZD4TACaot8H0bR8D23L ySp40BxxMq+oXusx1z8QEq56Gcy6IwgsSYbl8bEpH/6dpRebt9lznmGBTTtk5NwX7t Q97j8u24JQfFH/K1/zSpXU+s4RP/+JZxhw8kwvCbM7UbgSaF4yGncb6JdbFCGJeyT4 8e5GVRzCvv0KNWKK1hyjwS5jZjNxCCYUbkYdBMXSbjTqoFjyrBF0JuwESQRoU6weIn 8ioIlSAUata3gYwRmFZLJMd1FKYksDMex1zYtBGsgfRQruvoPRAy3A1jJ15lIPheG4 qcjCPyNSKplQQ== From: AngeloGioacchino Del Regno To: ryder.lee@mediatek.com Cc: jianjun.wang@mediatek.com, lpieralisi@kernel.org, kw@linux.com, robh@kernel.org, bhelgaas@google.com, p.zabel@pengutronix.de, matthias.bgg@gmail.com, angelogioacchino.delregno@collabora.com, linux-pci@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH 1/2] PCI: mediatek-gen3: Stop acquiring spinlocks in {suspend,resume}_noirq Date: Thu, 4 May 2023 13:35:08 +0200 Message-Id: <20230504113509.184633-2-angelogioacchino.delregno@collabora.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230504113509.184633-1-angelogioacchino.delregno@collabora.com> References: <20230504113509.184633-1-angelogioacchino.delregno@collabora.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org In mtk_pcie_suspend_noirq() and mtk_pcie_resume_noirq() we are, respectively, disabling and enabling generation of interrupts and then saving and restoring the enabled interrupts register: since we're using noirq PM callbacks, that can be safely done without holding any spin lock. That was noticed because of, and solves, the following issue: <4>[ 74.185982] ======================================================== <4>[ 74.192629] WARNING: possible irq lock inversion dependency detected <4>[ 74.199276] 6.3.0-next-20230428+ #51 Tainted: G W <4>[ 74.205664] -------------------------------------------------------- <4>[ 74.212309] systemd-sleep/809 just changed the state of lock: <4>[ 74.218347] ffff65a5c34c65a0 (&pcie->irq_lock){+...}-{2:2}, at: mtk_pcie_resume+0x50/0xa8 <4>[ 74.226870] but this lock was taken by another, HARDIRQ-safe lock in the past: <4>[ 74.234389] (&irq_desc_lock_class){-.-.}-{2:2} <4>[ 74.234409] <4>[ 74.234409] <4>[ 74.234409] and interrupts could create inverse lock ordering between them. <4>[ 74.234409] <4>[ 74.251704] <4>[ 74.251704] other info that might help us debug this: <4>[ 74.258785] Possible interrupt unsafe locking scenario: <4>[ 74.258785] <4>[ 74.266126] CPU0 CPU1 <4>[ 74.270942] ---- ---- <4>[ 74.275758] lock(&pcie->irq_lock); <4>[ 74.279627] local_irq_disable(); <4>[ 74.285836] lock(&irq_desc_lock_class); <4>[ 74.292667] lock(&pcie->irq_lock); <4>[ 74.299061] <4>[ 74.301960] lock(&irq_desc_lock_class); <4>[ 74.306438] <4>[ 74.306438] *** DEADLOCK *** Fixes: d537dc125f07 ("PCI: mediatek-gen3: Add system PM support") Signed-off-by: AngeloGioacchino Del Regno --- drivers/pci/controller/pcie-mediatek-gen3.c | 8 -------- 1 file changed, 8 deletions(-) diff --git a/drivers/pci/controller/pcie-mediatek-gen3.c b/drivers/pci/controller/pcie-mediatek-gen3.c index b8612ce5f4d0..52f52ca5db71 100644 --- a/drivers/pci/controller/pcie-mediatek-gen3.c +++ b/drivers/pci/controller/pcie-mediatek-gen3.c @@ -963,8 +963,6 @@ static void mtk_pcie_irq_save(struct mtk_gen3_pcie *pcie) { int i; - raw_spin_lock(&pcie->irq_lock); - pcie->saved_irq_state = readl_relaxed(pcie->base + PCIE_INT_ENABLE_REG); for (i = 0; i < PCIE_MSI_SET_NUM; i++) { @@ -973,16 +971,12 @@ static void mtk_pcie_irq_save(struct mtk_gen3_pcie *pcie) msi_set->saved_irq_state = readl_relaxed(msi_set->base + PCIE_MSI_SET_ENABLE_OFFSET); } - - raw_spin_unlock(&pcie->irq_lock); } static void mtk_pcie_irq_restore(struct mtk_gen3_pcie *pcie) { int i; - raw_spin_lock(&pcie->irq_lock); - writel_relaxed(pcie->saved_irq_state, pcie->base + PCIE_INT_ENABLE_REG); for (i = 0; i < PCIE_MSI_SET_NUM; i++) { @@ -991,8 +985,6 @@ static void mtk_pcie_irq_restore(struct mtk_gen3_pcie *pcie) writel_relaxed(msi_set->saved_irq_state, msi_set->base + PCIE_MSI_SET_ENABLE_OFFSET); } - - raw_spin_unlock(&pcie->irq_lock); } static int mtk_pcie_turn_off_link(struct mtk_gen3_pcie *pcie)