From patchwork Tue Nov 14 13:55:50 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johan Hovold X-Patchwork-Id: 13455329 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 5B27C405E3 for ; Tue, 14 Nov 2023 13:56:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="BBHOHfNc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CA8C7C43397; Tue, 14 Nov 2023 13:56:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1699970193; bh=FBrVwkCNQ13rjcfw1rE/Ykhh7nhHv9rEy/bYSmsBegQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BBHOHfNckzRz7mnu26EM4ZGNdr34Tk+SyDvwuccRYDg3/vBsf5XfdAI532RpNgedV N2JcKrllILDtvNuhJ1nbPIeWY5nSHp8yMzs02lrEnGHsngcHmdgVmFYB5nTN+iedLp dvT6K9UjGj7xIwUy0BOu+U75X49pqAxeZkUf7ZxLMW3AZ48e94dDU7baWsnE/IUxOa iaaixLJK/z0HBKHZwYXQuw/48ot5+xto239+Sedo42JooeUiqBl1f8et7L58/eNSHe YuICzi3eeb6/fxPrdVYw8HwDXX7YFZzoBaJw4GEid+wCUMf1pJd2tiDkUHS0LBHoQ/ u85joJ6WXsyug== Received: from johan by xi.lan with local (Exim 4.96.2) (envelope-from ) id 1r2tu2-0008PT-2c; Tue, 14 Nov 2023 14:56:30 +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 3/6] PCI: qcom: Fix deadlock when enabling ASPM Date: Tue, 14 Nov 2023 14:55:50 +0100 Message-ID: <20231114135553.32301-4-johan+linaro@kernel.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20231114135553.32301-1-johan+linaro@kernel.org> References: <20231114135553.32301-1-johan+linaro@kernel.org> Precedence: bulk X-Mailing-List: linux-arm-msm@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") Cc: Manivannan Sadhasivam Signed-off-by: Johan Hovold Reviewed-by: Manivannan Sadhasivam --- 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; }