From patchwork Tue Nov 28 08:15:09 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johan Hovold X-Patchwork-Id: 13470607 X-Patchwork-Delegate: bhelgaas@google.com Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 22B3F182CF; Tue, 28 Nov 2023 08:15:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="KePGVFYk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5B1DFC433CC; Tue, 28 Nov 2023 08:15:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1701159324; bh=ldSxVLm151+9Q08xzcfgehlwNmHacduIvn8mLdpw3MU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KePGVFYkKCg+fXwzHWo2HnyjhX9Zr2jHkmy1eiykrci56JAFiNLHSHkkizTcxo6eR uV0uD5HK0PstpCYwy9pmIUtUF5y29g+cvKeBILu5wlhdTCUa9W1cazuJSw8mi5eWLP /AN5grugmjvSA13X9F2lbf2ThCiNRQXxQ+pLo+A/7idYbx1GVcXs7pBpepX7aY0hk0 MrRzhRjdR7dcz1dBvDcOxRdD6dliCErptS7/zOTehlO1g/C1CHzmsKZsC9Pb73EI5P EpJpJoiD7TctTPQO4SHuVY5TcDNc+3fK9GvCZvqRVAjS095HAK8WgTlbJFPqsj2fNN TxIQQDR1TthLQ== Received: from johan by xi.lan with local (Exim 4.96.2) (envelope-from ) id 1r7tG4-00053t-2C; Tue, 28 Nov 2023 09:15:52 +0100 From: Johan Hovold To: "Lorenzo Pieralisi" , =?utf-8?q?Krzysztof_Wilczy?= =?utf-8?q?=C5=84ski?= , "Bjorn Helgaas" Cc: Andy Gross , Bjorn Andersson , Konrad Dybcio , Manivannan Sadhasivam , Rob Herring , Nirmal Patel , Jonathan Derrick , linux-arm-msm@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Johan Hovold , Manivannan Sadhasivam Subject: [PATCH v2 3/6] PCI: qcom: Fix deadlock when enabling ASPM Date: Tue, 28 Nov 2023 09:15:09 +0100 Message-ID: <20231128081512.19387-4-johan+linaro@kernel.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20231128081512.19387-1-johan+linaro@kernel.org> References: <20231128081512.19387-1-johan+linaro@kernel.org> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 The qcom_pcie_enable_aspm() helper is called from pci_walk_bus() during host init to enable ASPM. Since pci_walk_bus() already holds a pci_bus_sem read lock, use the new locked helper to enable link states in order to avoid a potential deadlock (e.g. in case someone takes a write lock before reacquiring the read lock). This issue was reported by lockdep: ============================================ WARNING: possible recursive locking detected 6.7.0-rc1 #4 Not tainted -------------------------------------------- kworker/u16:6/147 is trying to acquire lock: ffffbf3ff9d2cfa0 (pci_bus_sem){++++}-{3:3}, at: pci_enable_link_state+0x74/0x1e8 but task is already holding lock: ffffbf3ff9d2cfa0 (pci_bus_sem){++++}-{3:3}, at: pci_walk_bus+0x34/0xbc other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(pci_bus_sem); lock(pci_bus_sem); *** DEADLOCK *** Fixes: 9f4f3dfad8cf ("PCI: qcom: Enable ASPM for platforms supporting 1.9.0 ops") Reviewed-by: Manivannan Sadhasivam Signed-off-by: Johan Hovold --- drivers/pci/controller/dwc/pcie-qcom.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c index ce3ece28fed2..21523115f6a4 100644 --- a/drivers/pci/controller/dwc/pcie-qcom.c +++ b/drivers/pci/controller/dwc/pcie-qcom.c @@ -971,7 +971,7 @@ static int qcom_pcie_enable_aspm(struct pci_dev *pdev, void *userdata) { /* Downstream devices need to be in D0 state before enabling PCI PM substates */ pci_set_power_state(pdev, PCI_D0); - pci_enable_link_state(pdev, PCIE_LINK_STATE_ALL); + pci_enable_link_state_locked(pdev, PCIE_LINK_STATE_ALL); return 0; }