From: Keith Busch Date: Tue, 17 Feb 2026 16:08:36 +0000 (-0800) Subject: PCI: Make reset_subordinate hotplug safe X-Git-Tag: v7.1-rc1~151^2~24^2~2 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8238cb69c01fe4dbb4e3be277fff3ed680ac0108;p=thirdparty%2Fkernel%2Fstable.git PCI: Make reset_subordinate hotplug safe Use the slot reset method when resetting the bridge if the bus contains hot plug slots. This fixes spurious hot plug events that are triggered by the secondary bus reset that bypasses the slot's detection disabling. Resetting a bridge's subordinate bus can be done like this: # echo 1 > /sys/bus/pci/devices/0000:50:01.0/reset_subordinate Prior to this patch, an example kernel message may show something like: pcieport 0000:50:01.0: pciehp: Slot(40): Link Down With this change, the pciehp driver ignores the link event during the reset, so may show this message instead: pcieport 0000:50:01.0: pciehp: Slot(40): Link Down/Up ignored Signed-off-by: Keith Busch Signed-off-by: Bjorn Helgaas Reviewed-by: Dan Williams Link: https://patch.msgid.link/20260217160836.2709885-4-kbusch@meta.com --- diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index aaf92195da321..a2f8a5d6190fd 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -553,7 +553,6 @@ static ssize_t reset_subordinate_store(struct device *dev, const char *buf, size_t count) { struct pci_dev *pdev = to_pci_dev(dev); - struct pci_bus *bus = pdev->subordinate; unsigned long val; if (!capable(CAP_SYS_ADMIN)) @@ -563,7 +562,7 @@ static ssize_t reset_subordinate_store(struct device *dev, return -EINVAL; if (val) { - int ret = pci_try_reset_bus(bus); + int ret = pci_try_reset_bridge(pdev); if (ret) return ret; diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 4fd61d6cacff9..5984ad9ef6c46 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -5597,14 +5597,44 @@ static int pci_bus_reset(struct pci_bus *bus, bool probe) } /** - * pci_bus_error_reset - reset the bridge's subordinate bus - * @bridge: The parent device that connects to the bus to reset + * pci_try_reset_bus - Try to reset a PCI bus + * @bus: top level PCI bus to reset + * + * Same as above except return -EAGAIN if the bus cannot be locked + */ +static int pci_try_reset_bus(struct pci_bus *bus) +{ + int rc; + + rc = pci_bus_reset(bus, PCI_RESET_PROBE); + if (rc) + return rc; + + if (pci_bus_trylock(bus)) { + pci_bus_save_and_disable_locked(bus); + might_sleep(); + rc = pci_bridge_secondary_bus_reset(bus->self); + pci_bus_restore_locked(bus); + pci_bus_unlock(bus); + } else + rc = -EAGAIN; + + return rc; +} + +#define PCI_RESET_RESTORE true +#define PCI_RESET_NO_RESTORE false +/** + * pci_reset_bridge - reset a bridge's subordinate bus + * @bridge: bridge that connects to the bus to reset + * @restore: when true use a reset method that invokes pci_dev_restore() post + * reset for affected devices * * This function will first try to reset the slots on this bus if the method is * available. If slot reset fails or is not available, this will fall back to a * secondary bus reset. */ -int pci_bus_error_reset(struct pci_dev *bridge) +static int pci_reset_bridge(struct pci_dev *bridge, bool restore) { struct pci_bus *bus = bridge->subordinate; struct pci_slot *slot; @@ -5620,17 +5650,42 @@ int pci_bus_error_reset(struct pci_dev *bridge) if (pci_probe_reset_slot(slot)) goto bus_reset; - list_for_each_entry(slot, &bus->slots, list) - if (pci_slot_reset(slot, PCI_RESET_DO_RESET)) + list_for_each_entry(slot, &bus->slots, list) { + int ret; + + if (restore) + ret = pci_try_reset_slot(slot); + else + ret = pci_slot_reset(slot, PCI_RESET_DO_RESET); + + if (ret) goto bus_reset; + } mutex_unlock(&pci_slot_mutex); return 0; bus_reset: mutex_unlock(&pci_slot_mutex); + + if (restore) + return pci_try_reset_bus(bus); return pci_bus_reset(bridge->subordinate, PCI_RESET_DO_RESET); } +/** + * pci_bus_error_reset - reset the bridge's subordinate bus + * @bridge: The parent device that connects to the bus to reset + */ +int pci_bus_error_reset(struct pci_dev *bridge) +{ + return pci_reset_bridge(bridge, PCI_RESET_NO_RESTORE); +} + +int pci_try_reset_bridge(struct pci_dev *bridge) +{ + return pci_reset_bridge(bridge, PCI_RESET_RESTORE); +} + /** * pci_probe_reset_bus - probe whether a PCI bus can be reset * @bus: PCI bus to probe @@ -5643,32 +5698,6 @@ int pci_probe_reset_bus(struct pci_bus *bus) } EXPORT_SYMBOL_GPL(pci_probe_reset_bus); -/** - * pci_try_reset_bus - Try to reset a PCI bus - * @bus: top level PCI bus to reset - * - * Same as above except return -EAGAIN if the bus cannot be locked - */ -int pci_try_reset_bus(struct pci_bus *bus) -{ - int rc; - - rc = pci_bus_reset(bus, PCI_RESET_PROBE); - if (rc) - return rc; - - if (pci_bus_trylock(bus)) { - pci_bus_save_and_disable_locked(bus); - might_sleep(); - rc = pci_bridge_secondary_bus_reset(bus->self); - pci_bus_restore_locked(bus); - pci_bus_unlock(bus); - } else - rc = -EAGAIN; - - return rc; -} - /** * pci_reset_bus - Try to reset a PCI bus * @pdev: top level PCI device to reset via slot/bus diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h index e319417da5caa..a1d2ecb562077 100644 --- a/drivers/pci/pci.h +++ b/drivers/pci/pci.h @@ -231,7 +231,7 @@ bool pci_reset_supported(struct pci_dev *dev); void pci_init_reset_methods(struct pci_dev *dev); int pci_bridge_secondary_bus_reset(struct pci_dev *dev); int pci_bus_error_reset(struct pci_dev *dev); -int pci_try_reset_bus(struct pci_bus *bus); +int pci_try_reset_bridge(struct pci_dev *bridge); struct pci_cap_saved_data { u16 cap_nr;