wireguard-linux/drivers/pci/hotplug/pciehp.h, branch jd/unified-crypt-queue

PCI: pciehp: Disable in-band presence detect when possible

2020-02-21T04:44:30Z

The presence detect state (PDS) is normally a logical OR of in-band and out-of-band (OOB) presence detect. As of PCIe 4.0, there is the option to disable in-band presence so that the PDS bit always reflects the state of the out-of-band presence. The recommendation of the PCIe spec is to disable in-band presence whenever supported (PCIe r5.0, appendix I implementation note): Due to architectural issues, the in-band (Physical-Layer-based) portion of the PD mechanism is deprecated for use with async hot-plug. One issue is that in-band PD as architected does not detect adapter removal during certain LTSSM states, notably the L1 and Disabled States. Another issue is that when both in-band and OOB PD are being used together, the Presence Detect State bit and its associated interrupt mechanism always reflect the logical OR of the inband and OOB PD states, and with some hot-plug hardware configurations, it is important for software to detect and respond to in-band and OOB PD events independently. If OOB PD is being used and the associated DSP supports In-Band PD Disable, it is recommended that the In-Band PD Disable bit be Set, and the Presence Detect State bit and its associated interrupt mechanism be used exclusively for OOB PD. As a substitute for in-band PD with async hot-plug, the reference model uses either the DPC or the DLL Link Active mechanism. Link: https://lore.kernel.org/r/20191025190047.38130-2-stuart.w.hayes@gmail.com [bhelgaas: move PCI_EXP_SLTCAP2 read earlier & print PCI_EXP_SLTCAP2_IBPD value (suggested by Lukas)] Signed-off-by: Alexandru Gagniuc Signed-off-by: Bjorn Helgaas Reviewed-by: Andy Shevchenko Reviewed-by: Lukas Wunner

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: Avoid returning prematurely from sysfs requests

2019-10-04T20:39:36Z

A sysfs request to enable or disable a PCIe hotplug slot should not return before it has been carried out. That is sought to be achieved by waiting until the controller's "pending_events" have been cleared. However the IRQ thread pciehp_ist() clears the "pending_events" before it acts on them. If pciehp_sysfs_enable_slot() / _disable_slot() happen to check the "pending_events" after they have been cleared but while pciehp_ist() is still running, the functions may return prematurely with an incorrect return value. Fix by introducing an "ist_running" flag which must be false before a sysfs request is allowed to return. Fixes: 32a8cef274fe ("PCI: pciehp: Enable/disable exclusively from IRQ thread") Link: https://lore.kernel.org/linux-pci/1562226638-54134-1-git-send-email-wangxiongfeng2@huawei.com Link: https://lore.kernel.org/r/4174210466e27eb7e2243dd1d801d5f75baaffd8.1565345211.git.lukas@wunner.de Reported-and-tested-by: Xiongfeng Wang Signed-off-by: Lukas Wunner Signed-off-by: Bjorn Helgaas Cc: stable@vger.kernel.org # v4.19+

PCI: pciehp: Refer to "Indicators" instead of "LEDs" in comments

2019-09-05T20:52:24Z

The PCIe spec doesn't mention "green LEDs" or "amber LEDs". Replace those terms with "Power Indicator" and "Attention Indicator" so the comments match the spec language. Comment changes only. Signed-off-by: Bjorn Helgaas

PCI: pciehp: Remove pciehp_green_led_{on,off,blink}()

2019-09-05T20:45:00Z

Remove pciehp_green_led_{on,off,blink}() and use pciehp_set_indicators() instead, since the code is mostly the same. [bhelgaas: drop set_power_indicator() wrapper to reduce the number of interfaces] Link: https://lore.kernel.org/r/20190903111021.1559-5-efremov@linux.com Signed-off-by: Denis Efremov Signed-off-by: Bjorn Helgaas Reviewed-by: Kuppuswamy Sathyanarayanan

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: Add pciehp_set_indicators() to set both indicators

2019-09-05T20:39:36Z

Add pciehp_set_indicators() to set power and attention indicators with a single register write. This is a minor optimization because we frequently set both indicators and this can do it with a single command. It also reduces the number of interfaces related to the indicators and makes them more discoverable because callers use the PCI_EXP_SLTCTL_ATTN_IND_* and PCI_EXP_SLTCTL_PWR_IND_* definitions directly. [bhelgaas: extend commit log, s/PCI_EXP_SLTCTL_.*_IND_NONE/INDICATOR_NOOP/ so they don't look like things defined by the spec, add function doc, mask commands to make it obvious we only send valid commands (pcie_do_write_cmd() does mask it, but requires more effort to verify)] Link: https://lore.kernel.org/r/20190903111021.1559-2-efremov@linux.com Signed-off-by: Denis Efremov Signed-off-by: Bjorn Helgaas

PCI: pciehp: Remove pointless MY_NAME definition

2019-05-09T21:45:21Z

MY_NAME is only used once and offers no benefit, so remove it. Link: https://lore.kernel.org/lkml/20190509141456.223614-11-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