From mboxrd@z Thu Jan 1 00:00:00 1970 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 ACAA8129EFB; Mon, 18 Dec 2023 14:02:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="xFyQfmxJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3082BC433C8; Mon, 18 Dec 2023 14:02:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1702908160; bh=Z4dmaTdmDWsY9nietSOPQXWIoy/ikZKFGdorlM+yUPs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=xFyQfmxJpSwJ2PQSWicb51DcK4T87G2DvmcwmY6YHmIWQBNIpzkYKv9aB1FEyIHRu ZFLfjEOG+sAozDL64yXLjUztYZX4nrI3Wj0PRgYCB5eSCdccbkfR5t3lsZzkFiNJaB YyK47kkGgPiJrIgwit+xRSxXtxWsEaE8xDslvU2Q= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Johan Hovold , Bjorn Helgaas , Manivannan Sadhasivam , Michael Bottini , "David E. Box" Subject: [PATCH 6.6 075/166] PCI/ASPM: Add pci_enable_link_state_locked() Date: Mon, 18 Dec 2023 14:50:41 +0100 Message-ID: <20231218135108.402889951@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231218135104.927894164@linuxfoundation.org> References: <20231218135104.927894164@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Johan Hovold commit 718ab8226636a1a3a7d281f5d6a7ad7c925efe5a upstream. Add pci_enable_link_state_locked() 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") Link: https://lore.kernel.org/r/20231128081512.19387-2-johan+linaro@kernel.org Signed-off-by: Johan Hovold [bhelgaas: include helper name in subject, commit log] Signed-off-by: Bjorn Helgaas Reviewed-by: Manivannan Sadhasivam Cc: # 6.3 Cc: Michael Bottini Cc: David E. Box Signed-off-by: Greg Kroah-Hartman --- drivers/pci/pcie/aspm.c | 53 ++++++++++++++++++++++++++++++++++++------------ include/linux/pci.h | 3 ++ 2 files changed, 43 insertions(+), 13 deletions(-) --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -1102,17 +1102,7 @@ int pci_disable_link_state(struct pci_de } 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); @@ -1129,7 +1119,8 @@ int pci_enable_link_state(struct pci_dev 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) @@ -1150,12 +1141,48 @@ int pci_enable_link_state(struct pci_dev 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) { --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1803,6 +1803,7 @@ 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); @@ -1813,6 +1814,8 @@ static inline int pci_disable_link_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; }