The documentation for the freeze() method says that it "should quiesce the device so that it doesn't generate IRQs or DMA". The unspoken consequence of not doing this is that MSIs aimed at non-boot CPUs may get fully lost if they're sent during the period where the target CPU is offline. The current behavior of the USB subsystem still allows interrupts to come in after freeze, both in terms of remote wakeups and HC events related to things like root plug port activity. This can get controllers like XHCI, which is very sensitive to lost interrupts, in a wedged state. This series attempts to fully quiesce interrupts coming from USB across in a freeze or quiescent state. These patches are grouped together because they serve a united purpose, but are actually independent. They could be merged or reverted individually. You may be able to reproduce this issue on your own machine via the following: 1. Disable runtime PM on your XHCI controller 2. Aim your XHCI IRQ at a non-boot CPU (replace 174): echo 2 > /proc/irq/174/smp_affinity 3. Attempt to hibernate (no need to actually go all the way down). I run 2 and 3 in a loop, and can usually hit a hang or dead XHCI controller within 1-2 iterations. I happened to notice this on an Alderlake system where runtime PM is accidentally disabled for one of the XHCI controllers. Some more discussion and debugging can be found at [1]. [1] https://lore.kernel.org/linux-pci/CAE=gft4a-QL82iFJE_xRQ3JrMmz-KZKWREtz=MghhjFbJeK=8A@xxxxxxxxxxxxxx/T/#u Changes in v3: - Fix comment formatting and line wrap Changes in v2: - Introduced the patch to always disable remote wakeups - Removed the change to freeze_noirq/thaw_noirq Evan Green (2): USB: core: Disable remote wakeup for freeze/quiesce USB: hcd-pci: Fully suspend across freeze/thaw cycle drivers/usb/core/driver.c | 25 +++++++++++++------------ drivers/usb/core/hcd-pci.c | 4 ++-- 2 files changed, 15 insertions(+), 14 deletions(-) -- 2.31.0
