From patchwork Tue Nov 28 08:15:07 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johan Hovold X-Patchwork-Id: 13470608 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 E6F5517988; 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="QkpLci41" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5D744C433CD; 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=G81lMNlYRmVBLpcYlNH0IxVp3LwH9UwmbbiIFMtSKyE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QkpLci41j5c4/RwAOvrCgGLQRVEQeNuHQfWRex0yjoXcD/1OPbV51okOYGbrbtuXN pwEHt9iQjIV+MtIMRR1bNOTphsf5f5iWUWubq5Vy+kyQ2FcSz4TDDFM6MeS2398tD1 EUj8RzvEG2KVMbzgamNshxoXTgOhdALZa/uNc+7EstsNp2iGrWvPxbuuHS/MMvT5tE Sp1kPyrpE8sys1JQL5bhhIugjcaRYnkljbld6Xe03/hfjAVKa4ckkbk8MPykltfONQ ZtW4bCl4e+sLxTtPN2eYm8A7tt4LBVoD16+Q/YFgYir9yN7UBlb5cbItr4TFLM/a2u UBVw3iTDj4/6Q== Received: from johan by xi.lan with local (Exim 4.96.2) (envelope-from ) id 1r7tG4-00053p-1c; 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 , stable@vger.kernel.org, Michael Bottini , "David E . Box" , Manivannan Sadhasivam Subject: [PATCH v2 1/6] PCI/ASPM: Add locked helper for enabling link state Date: Tue, 28 Nov 2023 09:15:07 +0100 Message-ID: <20231128081512.19387-2-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 Add a helper for enabling link states that can be used in contexts where a pci_bus_sem read lock is already held (e.g. from pci_walk_bus()). This helper will be used to fix a couple of potential deadlocks where the current helper is called with the lock already held, hence the CC stable tag. Fixes: f492edb40b54 ("PCI: vmd: Add quirk to configure PCIe ASPM and LTR") Cc: stable@vger.kernel.org # 6.3 Cc: Michael Bottini Cc: David E. Box Reviewed-by: Manivannan Sadhasivam Signed-off-by: Johan Hovold --- drivers/pci/pcie/aspm.c | 53 +++++++++++++++++++++++++++++++---------- include/linux/pci.h | 3 +++ 2 files changed, 43 insertions(+), 13 deletions(-) diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index 50b04ae5c394..5eb462772354 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -1109,17 +1109,7 @@ int pci_disable_link_state(struct pci_dev *pdev, int state) } EXPORT_SYMBOL(pci_disable_link_state); -/** - * pci_enable_link_state - Clear and set the default device link state so that - * the link may be allowed to enter the specified states. Note that if the - * BIOS didn't grant ASPM control to the OS, this does nothing because we can't - * touch the LNKCTL register. Also note that this does not enable states - * disabled by pci_disable_link_state(). Return 0 or a negative errno. - * - * @pdev: PCI device - * @state: Mask of ASPM link states to enable - */ -int pci_enable_link_state(struct pci_dev *pdev, int state) +static int __pci_enable_link_state(struct pci_dev *pdev, int state, bool locked) { struct pcie_link_state *link = pcie_aspm_get_link(pdev); @@ -1136,7 +1126,8 @@ int pci_enable_link_state(struct pci_dev *pdev, int state) return -EPERM; } - down_read(&pci_bus_sem); + if (!locked) + down_read(&pci_bus_sem); mutex_lock(&aspm_lock); link->aspm_default = 0; if (state & PCIE_LINK_STATE_L0S) @@ -1157,12 +1148,48 @@ int pci_enable_link_state(struct pci_dev *pdev, int state) link->clkpm_default = (state & PCIE_LINK_STATE_CLKPM) ? 1 : 0; pcie_set_clkpm(link, policy_to_clkpm_state(link)); mutex_unlock(&aspm_lock); - up_read(&pci_bus_sem); + if (!locked) + up_read(&pci_bus_sem); return 0; } + +/** + * pci_enable_link_state - Clear and set the default device link state so that + * the link may be allowed to enter the specified states. Note that if the + * BIOS didn't grant ASPM control to the OS, this does nothing because we can't + * touch the LNKCTL register. Also note that this does not enable states + * disabled by pci_disable_link_state(). Return 0 or a negative errno. + * + * @pdev: PCI device + * @state: Mask of ASPM link states to enable + */ +int pci_enable_link_state(struct pci_dev *pdev, int state) +{ + return __pci_enable_link_state(pdev, state, false); +} EXPORT_SYMBOL(pci_enable_link_state); +/** + * pci_enable_link_state_locked - Clear and set the default device link state + * so that the link may be allowed to enter the specified states. Note that if + * the BIOS didn't grant ASPM control to the OS, this does nothing because we + * can't touch the LNKCTL register. Also note that this does not enable states + * disabled by pci_disable_link_state(). Return 0 or a negative errno. + * + * @pdev: PCI device + * @state: Mask of ASPM link states to enable + * + * Context: Caller holds pci_bus_sem read lock. + */ +int pci_enable_link_state_locked(struct pci_dev *pdev, int state) +{ + lockdep_assert_held_read(&pci_bus_sem); + + return __pci_enable_link_state(pdev, state, true); +} +EXPORT_SYMBOL(pci_enable_link_state_locked); + static int pcie_aspm_set_policy(const char *val, const struct kernel_param *kp) { diff --git a/include/linux/pci.h b/include/linux/pci.h index 60ca768bc867..dea043bc1e38 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1829,6 +1829,7 @@ extern bool pcie_ports_native; int pci_disable_link_state(struct pci_dev *pdev, int state); int pci_disable_link_state_locked(struct pci_dev *pdev, int state); int pci_enable_link_state(struct pci_dev *pdev, int state); +int pci_enable_link_state_locked(struct pci_dev *pdev, int state); void pcie_no_aspm(void); bool pcie_aspm_support_enabled(void); bool pcie_aspm_enabled(struct pci_dev *pdev); @@ -1839,6 +1840,8 @@ static inline int pci_disable_link_state_locked(struct pci_dev *pdev, int state) { return 0; } static inline int pci_enable_link_state(struct pci_dev *pdev, int state) { return 0; } +static inline int pci_enable_link_state_locked(struct pci_dev *pdev, int state) +{ return 0; } static inline void pcie_no_aspm(void) { } static inline bool pcie_aspm_support_enabled(void) { return false; } static inline bool pcie_aspm_enabled(struct pci_dev *pdev) { return false; }