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[98.195.139.126]) by smtp.gmail.com with ESMTPSA id x126-v6sm4926495oig.15.2018.07.23.13.01.26 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 23 Jul 2018 13:01:26 -0700 (PDT) From: Alexandru Gagniuc To: linux-pci@vger.kernel.org, bhelgaas@google.com Cc: keith.busch@intel.com, alex_gagniuc@dellteam.com, austin_bolen@dell.com, shyam_iyer@dell.com, jeffrey.t.kirsher@intel.com, ariel.elior@cavium.com, michael.chan@broadcom.com, ganeshgr@chelsio.com, tariqt@mellanox.com, jakub.kicinski@netronome.com, airlied@gmail.com, alexander.deucher@amd.com, mike.marciniszyn@intel.com, Alexandru Gagniuc , Frederick Lawler , Oza Pawandeep , Greg Kroah-Hartman , linux-kernel@vger.kernel.org Subject: [PATCH v2] PCI/AER: Do not clear AER bits if we don't own AER Date: Mon, 23 Jul 2018 15:01:08 -0500 Message-Id: <20180723200118.23657-1-mr.nuke.me@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180718215359.GG128988@bhelgaas-glaptop.roam.corp.google.com> References: <20180718215359.GG128988@bhelgaas-glaptop.roam.corp.google.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When we don't own AER, we shouldn't touch the AER error bits. Clearing error bits willy-nilly might cause firmware to miss some errors. In theory, these bits get cleared by FFS, or via ACPI _HPX method. These mechanisms are not subject to the problem. This race is mostly of theoretical significance, since I can't reasonably demonstrate this race in the lab. On a side-note, pcie_aer_is_kernel_first() is created to alleviate the need for two checks: aer_cap and get_firmware_first(). Signed-off-by: Alexandru Gagniuc --- drivers/pci/pcie/aer.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c index a2e88386af28..85c3e173c025 100644 --- a/drivers/pci/pcie/aer.c +++ b/drivers/pci/pcie/aer.c @@ -307,6 +307,12 @@ int pcie_aer_get_firmware_first(struct pci_dev *dev) aer_set_firmware_first(dev); return dev->__aer_firmware_first; } + +static bool pcie_aer_is_kernel_first(struct pci_dev *dev) +{ + return !!dev->aer_cap && !pcie_aer_get_firmware_first(dev); +} + #define PCI_EXP_AER_FLAGS (PCI_EXP_DEVCTL_CERE | PCI_EXP_DEVCTL_NFERE | \ PCI_EXP_DEVCTL_FERE | PCI_EXP_DEVCTL_URRE) @@ -337,10 +343,7 @@ bool aer_acpi_firmware_first(void) int pci_enable_pcie_error_reporting(struct pci_dev *dev) { - if (pcie_aer_get_firmware_first(dev)) - return -EIO; - - if (!dev->aer_cap) + if (!pcie_aer_is_kernel_first(dev)) return -EIO; return pcie_capability_set_word(dev, PCI_EXP_DEVCTL, PCI_EXP_AER_FLAGS); @@ -349,7 +352,7 @@ EXPORT_SYMBOL_GPL(pci_enable_pcie_error_reporting); int pci_disable_pcie_error_reporting(struct pci_dev *dev) { - if (pcie_aer_get_firmware_first(dev)) + if (!pcie_aer_is_kernel_first(dev)) return -EIO; return pcie_capability_clear_word(dev, PCI_EXP_DEVCTL, @@ -383,10 +386,10 @@ int pci_cleanup_aer_error_status_regs(struct pci_dev *dev) if (!pci_is_pcie(dev)) return -ENODEV; - pos = dev->aer_cap; - if (!pos) + if (pcie_aer_is_kernel_first(dev)) return -EIO; + pos = dev->aer_cap; port_type = pci_pcie_type(dev); if (port_type == PCI_EXP_TYPE_ROOT_PORT) { pci_read_config_dword(dev, pos + PCI_ERR_ROOT_STATUS, &status); -- 2.17.1