From 4b103883473964bbb7b0b6934999b283ee234a8a Mon Sep 17 00:00:00 2001 From: Keith Busch Date: Wed, 29 Mar 2017 22:49:06 -0500 Subject: [PATCH] PCI: Don't attempt config access to disconnected devices If we've detected the PCI device is disconnected, there is no need to attempt to access its config space since we know the operation will fail. Make all the config reads and writes return -ENODEV error immediately when in such a state. If a caller requests a config read to a disconnected device, return a data value of all 1's. This is the same as what hardware is expected to return when accessing a removed device, but software can do this faster without relying on hardware. Tested-by: Krishna Dhulipala Signed-off-by: Keith Busch Signed-off-by: Bjorn Helgaas Reviewed-by: Christoph Hellwig Reviewed-by: Wei Zhang --- drivers/pci/access.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/drivers/pci/access.c b/drivers/pci/access.c index c70e3113df7a..1c8051003e67 100644 --- a/drivers/pci/access.c +++ b/drivers/pci/access.c @@ -893,12 +893,20 @@ EXPORT_SYMBOL(pcie_capability_clear_and_set_dword); int pci_read_config_byte(const struct pci_dev *dev, int where, u8 *val) { + if (pci_dev_is_disconnected(dev)) { + *val = ~0; + return -ENODEV; + } return pci_bus_read_config_byte(dev->bus, dev->devfn, where, val); } EXPORT_SYMBOL(pci_read_config_byte); int pci_read_config_word(const struct pci_dev *dev, int where, u16 *val) { + if (pci_dev_is_disconnected(dev)) { + *val = ~0; + return -ENODEV; + } return pci_bus_read_config_word(dev->bus, dev->devfn, where, val); } EXPORT_SYMBOL(pci_read_config_word); @@ -906,18 +914,26 @@ EXPORT_SYMBOL(pci_read_config_word); int pci_read_config_dword(const struct pci_dev *dev, int where, u32 *val) { + if (pci_dev_is_disconnected(dev)) { + *val = ~0; + return -ENODEV; + } return pci_bus_read_config_dword(dev->bus, dev->devfn, where, val); } EXPORT_SYMBOL(pci_read_config_dword); int pci_write_config_byte(const struct pci_dev *dev, int where, u8 val) { + if (pci_dev_is_disconnected(dev)) + return -ENODEV; return pci_bus_write_config_byte(dev->bus, dev->devfn, where, val); } EXPORT_SYMBOL(pci_write_config_byte); int pci_write_config_word(const struct pci_dev *dev, int where, u16 val) { + if (pci_dev_is_disconnected(dev)) + return -ENODEV; return pci_bus_write_config_word(dev->bus, dev->devfn, where, val); } EXPORT_SYMBOL(pci_write_config_word); @@ -925,6 +941,8 @@ EXPORT_SYMBOL(pci_write_config_word); int pci_write_config_dword(const struct pci_dev *dev, int where, u32 val) { + if (pci_dev_is_disconnected(dev)) + return -ENODEV; return pci_bus_write_config_dword(dev->bus, dev->devfn, where, val); } EXPORT_SYMBOL(pci_write_config_dword);