linux-kernel - Re: [PATCH v1 1/1] s390/pci: Restore IRQ unconditionally for the zPCI device

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Message-ID: <20251023074028.9536A84-hca@linux.ibm.com>
Date: Thu, 23 Oct 2025 09:40:28 +0200
From: Heiko Carstens <hca@...ux.ibm.com>
To: Farhan Ali <alifm@...ux.ibm.com>
Cc: linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        schnelle@...ux.ibm.com, mjrosato@...ux.ibm.com, agordeev@...ux.ibm.com,
        gor@...ux.ibm.com
Subject: Re: [PATCH v1 1/1] s390/pci: Restore IRQ unconditionally for the
 zPCI device

On Wed, Oct 22, 2025 at 09:47:26AM -0700, Farhan Ali wrote:
> Commit c1e18c17bda6 ("s390/pci: add zpci_set_irq()/zpci_clear_irq()"),
> introduced the zpci_set_irq() and zpci_clear_irq(), to be used while
> resetting a zPCI device.
> 
> Commit da995d538d3a ("s390/pci: implement reset_slot for hotplug slot"),
> mentions zpci_clear_irq() being called in the path for zpci_hot_reset_device().
> But that is not the case anymore and these functions are not called
> outside of this file. Instead zpci_hot_reset_device() relies on
> zpci_disable_device() also clearing the IRQs, but misses to reset the
> zdev->irqs_registered flag.
> 
> However after a CLP disable/enable reset, the device's IRQ are
> unregistered, but the flag zdev->irq_registered does not get cleared. It
> creates an inconsistent state and so arch_restore_msi_irqs() doesn't
> correctly restore the device's IRQ. This becomes a problem when a PCI
> driver tries to restore the state of the device through
> pci_restore_state(). Restore IRQ unconditionally for the device and remove
> the irq_registered flag as its redundant.
> 
> Reviewed-by: Niklas Schnelle <schnelle@...ux.ibm.com>
> Reviewed-by: Matthew Rosato <mjrosato@...ux.ibm.com>
> Signed-off-by: Farhan Ali <alifm@...ux.ibm.com>
> ---
>  arch/s390/include/asm/pci.h | 1 -
>  arch/s390/pci/pci_irq.c     | 9 +--------
>  2 files changed, 1 insertion(+), 9 deletions(-)

The above sounds like this fixes a regression. Is there a reason why
there are no Fixes and stable tags?