Patch "usb: ohci: Prevent missed ohci interrupts" has been added to the 5.10-stable tree

[<gregkh@xxxxxxxxxxxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    usb: ohci: Prevent missed ohci interrupts

to the 5.10-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:
     usb-ohci-prevent-missed-ohci-interrupts.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From fe81f354841641c7f71163b84912b25c169ed8ec Mon Sep 17 00:00:00 2001
From: Guenter Roeck <linux@xxxxxxxxxxxx>
Date: Mon, 29 Apr 2024 08:40:10 -0700
Subject: usb: ohci: Prevent missed ohci interrupts

From: Guenter Roeck <linux@xxxxxxxxxxxx>

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@xxxxxxxxxx>
Cc: David Laight <David.Laight@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 306c54d0edb6 ("usb: hcd: Try MSI interrupts on PCI devices")
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Reviewed-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240429154010.1507366-1-linux@xxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 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
@@ -890,6 +890,7 @@ 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");
@@ -984,6 +985,13 @@ 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, &regs->intrstatus);
+		if (ints && (ints & ohci_readl(ohci, &regs->intrenable)))
+			goto again;
+	}
+
 	return IRQ_HANDLED;
 }
 


Patches currently in stable-queue which might be from linux@xxxxxxxxxxxx are

queue-5.10/usb-ohci-prevent-missed-ohci-interrupts.patch
queue-5.10/hwmon-corsair-cpro-use-complete_all-instead-of-compl.patch
queue-5.10/hwmon-corsair-cpro-use-a-separate-buffer-for-sending.patch
queue-5.10/hwmon-corsair-cpro-protect-ccp-wait_input_report-wit.patch