wireguard-linux/drivers/pci/hotplug/pciehp_core.c, branch jd/unified-crypt-queue

PCI: pciehp: Prevent deadlock on disconnect

2019-11-12T23:17:42Z

This addresses deadlocks in these common cases in hierarchies containing two switches: - All involved ports are runtime suspended and they are unplugged. This can happen easily if the drivers involved automatically enable runtime PM (xHCI for example does that). - System is suspended (e.g., closing the lid on a laptop) with a dock + something else connected, and the dock is unplugged while suspended. These cases lead to the following deadlock: INFO: task irq/126-pciehp:198 blocked for more than 120 seconds. irq/126-pciehp D 0 198 2 0x80000000 Call Trace: schedule+0x2c/0x80 schedule_timeout+0x246/0x350 wait_for_completion+0xb7/0x140 kthread_stop+0x49/0x110 free_irq+0x32/0x70 pcie_shutdown_notification+0x2f/0x50 pciehp_remove+0x27/0x50 pcie_port_remove_service+0x36/0x50 device_release_driver+0x12/0x20 bus_remove_device+0xec/0x160 device_del+0x13b/0x350 device_unregister+0x1a/0x60 remove_iter+0x1e/0x30 device_for_each_child+0x56/0x90 pcie_port_device_remove+0x22/0x40 pcie_portdrv_remove+0x20/0x60 pci_device_remove+0x3e/0xc0 device_release_driver_internal+0x18c/0x250 device_release_driver+0x12/0x20 pci_stop_bus_device+0x6f/0x90 pci_stop_bus_device+0x31/0x90 pci_stop_and_remove_bus_device+0x12/0x20 pciehp_unconfigure_device+0x88/0x140 pciehp_disable_slot+0x6a/0x110 pciehp_handle_presence_or_link_change+0x263/0x400 pciehp_ist+0x1c9/0x1d0 irq_thread_fn+0x24/0x60 irq_thread+0xeb/0x190 kthread+0x120/0x140 INFO: task irq/190-pciehp:2288 blocked for more than 120 seconds. irq/190-pciehp D 0 2288 2 0x80000000 Call Trace: __schedule+0x2a2/0x880 schedule+0x2c/0x80 schedule_preempt_disabled+0xe/0x10 mutex_lock+0x2c/0x30 pci_lock_rescan_remove+0x15/0x20 pciehp_unconfigure_device+0x4d/0x140 pciehp_disable_slot+0x6a/0x110 pciehp_handle_presence_or_link_change+0x263/0x400 pciehp_ist+0x1c9/0x1d0 irq_thread_fn+0x24/0x60 irq_thread+0xeb/0x190 kthread+0x120/0x140 What happens here is that the whole hierarchy is runtime resumed and the parent PCIe downstream port, which got the hot-remove event, starts removing devices below it, taking pci_lock_rescan_remove() lock. When the child PCIe port is runtime resumed it calls pciehp_check_presence() which ends up calling pciehp_card_present() and pciehp_check_link_active(). Both of these use pcie_capability_read_word(), which notices that the underlying device is already gone and returns PCIBIOS_DEVICE_NOT_FOUND with the capability value set to 0. When pciehp gets this value it thinks that its child device is also hot-removed and schedules its IRQ thread to handle the event. The deadlock happens when the child's IRQ thread runs and tries to acquire pci_lock_rescan_remove() which is already taken by the parent and the parent waits for the child's IRQ thread to finish. Prevent this from happening by checking the return value of pcie_capability_read_word() and if it is PCIBIOS_DEVICE_NOT_FOUND stop performing any hot-removal activities. [bhelgaas: add common scenarios to commit log] Link: https://lore.kernel.org/r/20191029170022.57528-2-mika.westerberg@linux.intel.com Tested-by: Kai-Heng Feng Signed-off-by: Mika Westerberg Signed-off-by: Bjorn Helgaas

PCI: pciehp: Do not disable interrupt twice on suspend

2019-11-12T22:27:33Z

We try to keep PCIe hotplug ports runtime suspended when entering system suspend. Because the PCIe portdrv sets the DPM_FLAG_NEVER_SKIP flag, the PM core always calls system suspend/resume hooks even if the device is left runtime suspended. Since PCIe hotplug driver re-used the same function for both runtime suspend and system suspend, it ended up disabling hotplug interrupt twice and the second time following was printed: pciehp 0000:03:01.0:pcie204: pcie_do_write_cmd: no response from device Prevent this from happening by checking whether the device is already runtime suspended when the system suspend hook is called. Fixes: 9c62f0bfb832 ("PCI: pciehp: Implement runtime PM callbacks") Link: https://lore.kernel.org/r/20191029170022.57528-1-mika.westerberg@linux.intel.com Reported-by: Kai-Heng Feng Tested-by: Kai-Heng Feng Signed-off-by: Mika Westerberg Signed-off-by: Bjorn Helgaas Reviewed-by: Rafael J. Wysocki

PCI: pciehp: Remove pciehp_set_attention_status()

2019-09-05T20:44:08Z

Remove pciehp_set_attention_status() and use pciehp_set_indicators() instead, since the code is mostly the same. Link: https://lore.kernel.org/r/20190903111021.1559-4-efremov@linux.com Signed-off-by: Denis Efremov Signed-off-by: Bjorn Helgaas Reviewed-by: Kuppuswamy Sathyanarayanan

PCI: pciehp: Remove pointless PCIE_MODULE_NAME definition

2019-05-09T21:45:21Z

PCIE_MODULE_NAME is only used once and offers no benefit, so remove it. Link: https://lore.kernel.org/lkml/20190509141456.223614-10-helgaas@kernel.org Signed-off-by: Bjorn Helgaas Reviewed-by: Keith Busch Reviewed-by: Andy Shevchenko

PCI: pciehp: Remove unused dbg/err/info/warn() wrappers

2019-05-09T21:45:20Z

Replace the last uses of dbg() with the equivalent pr_debug(), then remove unused dbg(), err(), info(), and warn() wrappers. Link: https://lore.kernel.org/lkml/20190509141456.223614-9-helgaas@kernel.org Signed-off-by: Frederick Lawler Signed-off-by: Bjorn Helgaas Reviewed-by: Keith Busch Reviewed-by: Andy Shevchenko

PCI: pciehp: Log messages with pci_dev, not pcie_device

2019-05-09T21:45:20Z

Log messages with pci_dev, not pcie_device. Factor out common message prefixes with dev_fmt(). Example output change: - pciehp 0000:00:06.0:pcie004: Slot(0) Powering on due to button press + pcieport 0000:00:06.0: pciehp: Slot(0) Powering on due to button press Link: https://lore.kernel.org/lkml/20190509141456.223614-8-helgaas@kernel.org Signed-off-by: Frederick Lawler Signed-off-by: Bjorn Helgaas Reviewed-by: Keith Busch Reviewed-by: Andy Shevchenko

PCI: pciehp: Replace pciehp_debug module param with dyndbg

2019-05-09T21:45:20Z

Previously pciehp debug messages were enabled by the pciehp_debug module parameter, e.g., by booting with this kernel command line option: pciehp.pciehp_debug=1 Convert this mechanism to use the generic dynamic debug (dyndbg) feature. After this commit, pciehp debug messages are enabled by building the kernel with CONFIG_DYNAMIC_DEBUG=y and booting with this command line option: dyndbg="file pciehp* +p" The dyndbg facility is much more flexible: messages can be enabled at boot- or run-time based on the file name, function name, line number, message test, etc. See Documentation/admin-guide/dynamic-debug-howto.rst for more details. Link: https://lore.kernel.org/lkml/20190509141456.223614-7-helgaas@kernel.org Signed-off-by: Frederick Lawler [bhelgaas: commit log, comment, remove pciehp_debug parameter] Signed-off-by: Bjorn Helgaas Reviewed-by: Keith Busch Reviewed-by: Andy Shevchenko

PCI: pciehp: Implement runtime PM callbacks

2018-10-02T21:04:40Z

Basically we need to do the same thing when runtime suspending than with system sleep so re-use those operations here. This makes sure hotplug interrupt does not trigger immediately when the link goes down. Signed-off-by: Mika Westerberg Signed-off-by: Bjorn Helgaas Reviewed-by: Rafael J. Wysocki

PCI: pciehp: Disable hotplug interrupt during suspend

2018-10-02T21:04:40Z

When PCIe hotplug port is transitioned into D3hot, the link to the downstream component will go down. If hotplug interrupt generation is enabled when that happens, it will trigger immediately, waking up the system and bringing the link back up. To prevent this, disable hotplug interrupt generation when system suspend is entered. This does not prevent wakeup from low power states according to PCIe 4.0 spec section 6.7.3.4: Software enables a hot-plug event to generate a wakeup event by enabling software notification of the event as described in Section 6.7.3.1. Note that in order for software to disable interrupt generation while keeping wakeup generation enabled, the Hot-Plug Interrupt Enable bit must be cleared. So as long as we have set the slot event mask accordingly, wakeup should work even if slot interrupt is disabled. The port should trigger wake and then send PME to the root port when the PCIe hierarchy is brought back up. Limit this to systems using native PME mechanism to make sure older Apple systems depending on commit e3354628c376 ("PCI: pciehp: Support interrupts sent from D3hot") still continue working. Signed-off-by: Mika Westerberg Signed-off-by: Bjorn Helgaas Reviewed-by: Rafael J. Wysocki

PCI: portdrv: Initialize service drivers directly

2018-09-20T17:05:54Z

The PCI port driver saves the PCI state after initializing the device with the applicable service devices. This was, however, before the service drivers were even registered because PCI probe happens before the device_initcall initialized those service drivers. The config space state that the services set up were not being saved. The end result would cause PCI devices to not react to events that the drivers think they did if the PCI state ever needed to be restored. Fix this by changing the service drivers from using the init calls to having the portdrv driver calling the services directly. This will get the state saved as desired, while making the relationship between the port driver and the services under it more explicit in the code. Signed-off-by: Keith Busch Signed-off-by: Bjorn Helgaas Reviewed-by: Sinan Kaya