This is a note to let you know that I've just added the patch titled
PCI: hotplug: Allow marking devices as disconnected during bind/unbind
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
pci-hotplug-allow-marking-devices-as-disconnected-during-bind-unbind.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 74ff8864cc842be994853095dba6db48e716400a Mon Sep 17 00:00:00 2001
From: Lukas Wunner <lukas@xxxxxxxxx>
Date: Fri, 20 Jan 2023 10:19:02 +0100
Subject: PCI: hotplug: Allow marking devices as disconnected during bind/unbind
From: Lukas Wunner <lukas@xxxxxxxxx>
commit 74ff8864cc842be994853095dba6db48e716400a upstream.
On surprise removal, pciehp_unconfigure_device() and acpiphp's
trim_stale_devices() call pci_dev_set_disconnected() to mark removed
devices as permanently offline. Thereby, the PCI core and drivers know
to skip device accesses.
However pci_dev_set_disconnected() takes the device_lock and thus waits for
a concurrent driver bind or unbind to complete. As a result, the driver's
->probe and ->remove hooks have no chance to learn that the device is gone.
That doesn't make any sense, so drop the device_lock and instead use atomic
xchg() and cmpxchg() operations to update the device state.
As a byproduct, an AB-BA deadlock reported by Anatoli is fixed which occurs
on surprise removal with AER concurrently performing a bus reset.
AER bus reset:
INFO: task irq/26-aerdrv:95 blocked for more than 120 seconds.
Tainted: G W 6.2.0-rc3-custom-norework-jan11+
schedule
rwsem_down_write_slowpath
down_write_nested
pciehp_reset_slot # acquires reset_lock
pci_reset_hotplug_slot
pci_slot_reset # acquires device_lock
pci_bus_error_reset
aer_root_reset
pcie_do_recovery
aer_process_err_devices
aer_isr
pciehp surprise removal:
INFO: task irq/26-pciehp:96 blocked for more than 120 seconds.
Tainted: G W 6.2.0-rc3-custom-norework-jan11+
schedule_preempt_disabled
__mutex_lock
mutex_lock_nested
pci_dev_set_disconnected # acquires device_lock
pci_walk_bus
pciehp_unconfigure_device
pciehp_disable_slot
pciehp_handle_presence_or_link_change
pciehp_ist # acquires reset_lock
Link: https://bugzilla.kernel.org/show_bug.cgi?id=215590
Fixes: a6bd101b8f84 ("PCI: Unify device inaccessible")
Link: https://lore.kernel.org/r/3dc88ea82bdc0e37d9000e413d5ebce481cbd629.1674205689.git.lukas@xxxxxxxxx
Reported-by: Anatoli Antonovitch <anatoli.antonovitch@xxxxxxx>
Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v4.20+
Cc: Keith Busch <kbusch@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/pci/pci.h | 43 +++++++++++++------------------------------
1 file changed, 13 insertions(+), 30 deletions(-)
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -347,53 +347,36 @@ struct pci_sriov {
* @dev: PCI device to set new error_state
* @new: the state we want dev to be in
*
- * Must be called with device_lock held.
+ * If the device is experiencing perm_failure, it has to remain in that state.
+ * Any other transition is allowed.
*
* Returns true if state has been changed to the requested state.
*/
static inline bool pci_dev_set_io_state(struct pci_dev *dev,
pci_channel_state_t new)
{
- bool changed = false;
+ pci_channel_state_t old;
- device_lock_assert(&dev->dev);
switch (new) {
case pci_channel_io_perm_failure:
- switch (dev->error_state) {
- case pci_channel_io_frozen:
- case pci_channel_io_normal:
- case pci_channel_io_perm_failure:
- changed = true;
- break;
- }
- break;
+ xchg(&dev->error_state, pci_channel_io_perm_failure);
+ return true;
case pci_channel_io_frozen:
- switch (dev->error_state) {
- case pci_channel_io_frozen:
- case pci_channel_io_normal:
- changed = true;
- break;
- }
- break;
+ old = cmpxchg(&dev->error_state, pci_channel_io_normal,
+ pci_channel_io_frozen);
+ return old != pci_channel_io_perm_failure;
case pci_channel_io_normal:
- switch (dev->error_state) {
- case pci_channel_io_frozen:
- case pci_channel_io_normal:
- changed = true;
- break;
- }
- break;
+ old = cmpxchg(&dev->error_state, pci_channel_io_frozen,
+ pci_channel_io_normal);
+ return old != pci_channel_io_perm_failure;
+ default:
+ return false;
}
- if (changed)
- dev->error_state = new;
- return changed;
}
static inline int pci_dev_set_disconnected(struct pci_dev *dev, void *unused)
{
- device_lock(&dev->dev);
pci_dev_set_io_state(dev, pci_channel_io_perm_failure);
- device_unlock(&dev->dev);
return 0;
}
Patches currently in stable-queue which might be from lukas@xxxxxxxxx are
queue-5.15/pci-hotplug-allow-marking-devices-as-disconnected-during-bind-unbind.patch
queue-5.15/pci-pm-observe-reset-delay-irrespective-of-bridge_d3.patch
