On 4/24/24 15:49, Greg Kroah-Hartman wrote:
On Wed, Apr 24, 2024 at 06:30:06PM -0400, Alan Stern wrote:
On Wed, Apr 24, 2024 at 12:59:51PM -0700, Guenter Roeck wrote:
Testing ohci functionality with qemu's pci-ohci emulation often results
in ohci interface stalls, resulting in hung task timeouts.
The problem is caused by lost interrupts between the emulation and the
Linux kernel code. Additional interrupts raised while the ohci interrupt
handler in Linux is running and before the handler clears the interrupt
status are not handled. The fix for a similar problem in ehci suggests
that the problem is likely caused by edge-triggered MSI interrupts. See
commit 0b60557230ad ("usb: ehci: Prevent missed ehci interrupts with
edge-triggered MSI") for details.
Ensure that the ohci interrupt code handles all pending interrupts before
returning to solve the problem.
Cc: Gerd Hoffmann <kraxel@xxxxxxxxxx>
Fixes: 306c54d0edb6 ("usb: hcd: Try MSI interrupts on PCI devices")
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
---
v2: Only repeat if the interface is still active
Reviewed-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Greg might insist that the patch be CC'ed to stable@xxxxxxxxxxxxxxx since
it contains a Fixes: tag.
I'll add that by hand, no worries.
Thanks!
Guenter
