linux-stable.git/drivers/pci/hotplug/pciehp_ctrl.c, branch linux-5.6.y

PCI: pciehp: Prevent deadlock on disconnect

2019-11-12T23:17:42+00:00

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

2019-10-04T20:39:36+00:00

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

2019-09-05T20:52:24+00:00

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}()

2019-09-05T20:45:00+00:00

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: Combine adjacent indicator updates

2019-09-05T20:43:33+00:00

Combine adjacent updates of power and attention indicators into a single
pciehp_set_indicators() call.  This sends one command to the hotplug
controller instead of two.

Link: https://lore.kernel.org/r/20190903111021.1559-3-efremov@linux.com
Signed-off-by: Denis Efremov 
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Kuppuswamy Sathyanarayanan 
Reviewed-by: Lukas Wunner

Merge tag 'pci-v5.2-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci

2019-05-14T17:30:10+00:00

Pull PCI updates from Bjorn Helgaas:
 "Enumeration changes:

   - Add _HPX Type 3 settings support, which gives firmware more
     influence over device configuration (Alexandru Gagniuc)

   - Support fixed bus numbers from bridge Enhanced Allocation
     capabilities (Subbaraya Sundeep)

   - Add "external-facing" DT property to identify cases where we
     require IOMMU protection against untrusted devices (Jean-Philippe
     Brucker)

   - Enable PCIe services for host controller drivers that use managed
     host bridge alloc (Jean-Philippe Brucker)

   - Log PCIe port service messages with pci_dev, not the pcie_device
     (Frederick Lawler)

   - Convert pciehp from pciehp_debug module parameter to generic
     dynamic debug (Frederick Lawler)

  Peer-to-peer DMA:

   - Add whitelist of Root Complexes that support peer-to-peer DMA
     between Root Ports (Christian König)

  Native controller drivers:

   - Add PCI host bridge DMA ranges for bridges that can't DMA
     everywhere, e.g., iProc (Srinath Mannam)

   - Add Amazon Annapurna Labs PCIe host controller driver (Jonathan
     Chocron)

   - Fix Tegra MSI target allocation so DMA doesn't generate unwanted
     MSIs (Vidya Sagar)

   - Fix of_node reference leaks (Wen Yang)

   - Fix Hyper-V module unload & device removal issues (Dexuan Cui)

   - Cleanup R-Car driver (Marek Vasut)

   - Cleanup Keystone driver (Kishon Vijay Abraham I)

   - Cleanup i.MX6 driver (Andrey Smirnov)

  Significant bug fixes:

   - Reset Lenovo ThinkPad P50 GPU so nouveau works after reboot (Lyude
     Paul)

   - Fix Switchtec firmware update performance issue (Wesley Sheng)

   - Work around Pericom switch link retraining erratum (Stefan Mätje)"

* tag 'pci-v5.2-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci: (141 commits)
  MAINTAINERS: Add Karthikeyan Mitran and Hou Zhiqiang for Mobiveil PCI
  PCI: pciehp: Remove pointless MY_NAME definition
  PCI: pciehp: Remove pointless PCIE_MODULE_NAME definition
  PCI: pciehp: Remove unused dbg/err/info/warn() wrappers
  PCI: pciehp: Log messages with pci_dev, not pcie_device
  PCI: pciehp: Replace pciehp_debug module param with dyndbg
  PCI: pciehp: Remove pciehp_debug uses
  PCI/AER: Log messages with pci_dev, not pcie_device
  PCI/DPC: Log messages with pci_dev, not pcie_device
  PCI/PME: Replace dev_printk(KERN_DEBUG) with dev_info()
  PCI/AER: Replace dev_printk(KERN_DEBUG) with dev_info()
  PCI: Replace dev_printk(KERN_DEBUG) with dev_info(), etc
  PCI: Replace printk(KERN_INFO) with pr_info(), etc
  PCI: Use dev_printk() when possible
  PCI: Cleanup setup-bus.c comments and whitespace
  PCI: imx6: Allow asynchronous probing
  PCI: dwc: Save root bus for driver remove hooks
  PCI: dwc: Use devm_pci_alloc_host_bridge() to simplify code
  PCI: dwc: Free MSI in dw_pcie_host_init() error path
  PCI: dwc: Free MSI IRQ page in dw_pcie_free_msi()
  ...

PCI: pciehp: Log messages with pci_dev, not pcie_device

2019-05-09T21:45:20+00:00

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: Ignore Link State Changes after powering off a slot

2019-04-10T21:06:43+00:00

During a safe hot remove, the OS powers off the slot, which may cause a
Data Link Layer State Changed event.  The slot has already been set to
OFF_STATE, so that event results in re-enabling the device, making it
impossible to safely remove it.

Clear out the Presence Detect Changed and Data Link Layer State Changed
events when the disabled slot has settled down.

It is still possible to re-enable the device if it remains in the slot
after pressing the Attention Button by pressing it again.

Fixes the problem that Micah reported below: an NVMe drive power button may
not actually turn off the drive.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=203237
Reported-by: Micah Parrish 
Tested-by: Micah Parrish 
Signed-off-by: Sergey Miroshnichenko 
[bhelgaas: changelog, add bugzilla URL]
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Lukas Wunner 
Cc: stable@vger.kernel.org	# v4.19+

PCI: hotplug: Embed hotplug_slot

2018-09-18T22:52:15+00:00

When the PCI hotplug core and its first user, cpqphp, were introduced in
February 2002 with historic commit a8a2069f432c, cpqphp allocated a slot
struct for its internal use plus a hotplug_slot struct to be registered
with the hotplug core and linked the two with pointers:
https://git.kernel.org/tglx/history/c/a8a2069f432c

Nowadays, the predominant pattern in the tree is to embed ("subclass")
such structures in one another and cast to the containing struct with
container_of().  But it wasn't until July 2002 that container_of() was
introduced with historic commit ec4f214232cf:
https://git.kernel.org/tglx/history/c/ec4f214232cf

pnv_php, introduced in 2016, did the right thing and embedded struct
hotplug_slot in its internal struct pnv_php_slot, but all other drivers
cargo-culted cpqphp's design and linked separate structs with pointers.

Embedding structs is preferrable to linking them with pointers because
it requires fewer allocations, thereby reducing overhead and simplifying
error paths.  Casting an embedded struct to the containing struct
becomes a cheap subtraction rather than a dereference.  And having fewer
pointers reduces the risk of them pointing nowhere either accidentally
or due to an attack.

Convert all drivers to embed struct hotplug_slot in their internal slot
struct.  The "private" pointer in struct hotplug_slot thereby becomes
unused, so drop it.

Signed-off-by: Lukas Wunner 
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Rafael J. Wysocki 
Acked-by: Tyrel Datwyler   # drivers/pci/hotplug/rpa*
Acked-by: Sebastian Ott         # drivers/pci/hotplug/s390*
Acked-by: Andy Shevchenko  # drivers/platform/x86
Cc: Len Brown 
Cc: Scott Murray 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Michael Ellerman 
Cc: Oliver OHalloran 
Cc: Gavin Shan 
Cc: Gerald Schaefer 
Cc: Corentin Chary 
Cc: Darren Hart

PCI: pciehp: Rename controller struct members for clarity

2018-09-18T22:52:15+00:00

Of the members which were just moved from pciehp's slot struct to the
controller struct, rename "lock" to "state_lock" and rename "work" to
"button_work" for clarity.  Perform the rename separately to the
unification of the two structs per Sinan's request.

No functional change intended.

Signed-off-by: Lukas Wunner 
Signed-off-by: Bjorn Helgaas 
Cc: Sinan Kaya