6.8-stable review patch. If anyone has any objections, please let me know.
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From: Guenter Roeck linux@roeck-us.net
commit fe81f354841641c7f71163b84912b25c169ed8ec upstream.
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@redhat.com Cc: David Laight David.Laight@aculab.com Cc: stable@vger.kernel.org Fixes: 306c54d0edb6 ("usb: hcd: Try MSI interrupts on PCI devices") Signed-off-by: Guenter Roeck linux@roeck-us.net Reviewed-by: Alan Stern stern@rowland.harvard.edu Reviewed-by: Gerd Hoffmann kraxel@redhat.com Link: https://lore.kernel.org/r/20240429154010.1507366-1-linux@roeck-us.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/host/ohci-hcd.c | 8 ++++++++ 1 file changed, 8 insertions(+)
--- a/drivers/usb/host/ohci-hcd.c +++ b/drivers/usb/host/ohci-hcd.c @@ -888,6 +888,7 @@ static irqreturn_t ohci_irq (struct usb_ /* Check for an all 1's result which is a typical consequence * of dead, unclocked, or unplugged (CardBus...) devices */ +again: if (ints == ~(u32)0) { ohci->rh_state = OHCI_RH_HALTED; ohci_dbg (ohci, "device removed!\n"); @@ -982,6 +983,13 @@ static irqreturn_t ohci_irq (struct usb_ } spin_unlock(&ohci->lock);
+ /* repeat until all enabled interrupts are handled */ + if (ohci->rh_state != OHCI_RH_HALTED) { + ints = ohci_readl(ohci, ®s->intrstatus); + if (ints && (ints & ohci_readl(ohci, ®s->intrenable))) + goto again; + } + return IRQ_HANDLED; }