Re: [PATCH] PCI: plda: Synchronize chained IRQs during deinitialization

[Bjorn Helgaas <helgaas@kernel.org>]

On Tue, Jul 14, 2026 at 10:43:45PM +0500, Ali Tariq wrote:
> During driver unbind or probe failure teardown,
> plda_pcie_irq_domain_deinit() unlinks the chained interrupt
> handlers for the main, MSI, and INTx interrupts using
> irq_set_chained_handler_and_data(). However, this function
> only updates the handler pointers and does not wait for any
> in-flight interrupt handlers running on other CPUs to finish.
> 
> If a PCIe interrupt fires concurrently with the teardown
> process, the handler could continue running on another CPU.
> If the hardware clocks are disabled shortly after in
> host_deinit(), the executing handler will attempt to read
> un-clocked PCIe registers, triggering a fatal system bus
> fault (external abort) or kernel panic.
> 
> Add synchronize_irq() after clearing each chained handler to
> guarantee that any executing handlers have fully completed
> before proceeding with interrupt domain removal and hardware
> deinitialization.
> 
> Fixes: 76c911396807 ("PCI: plda: Add host init/deinit and map bus functions")
> Signed-off-by: Ali Tariq <alitariq45892@gmail.com>
> ---
>  drivers/pci/controller/plda/pcie-plda-host.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/pci/controller/plda/pcie-plda-host.c b/drivers/pci/controller/plda/pcie-plda-host.c
> index f9a34f323ad8..f6759e255c75 100644
> --- a/drivers/pci/controller/plda/pcie-plda-host.c
> +++ b/drivers/pci/controller/plda/pcie-plda-host.c
> @@ -560,8 +560,13 @@ EXPORT_SYMBOL_GPL(plda_pcie_setup_iomems);
>  static void plda_pcie_irq_domain_deinit(struct plda_pcie_rp *pcie)
>  {
>  	irq_set_chained_handler_and_data(pcie->irq, NULL, NULL);
> +	synchronize_irq(pcie->irq);
> +
>  	irq_set_chained_handler_and_data(pcie->msi_irq, NULL, NULL);
> +	synchronize_irq(pcie->msi_irq);
> +
>  	irq_set_chained_handler_and_data(pcie->intx_irq, NULL, NULL);
> +	synchronize_irq(pcie->intx_irq);

Several other drivers call irq_set_chained_handler_and_data(..., NULL)
without synchronize_irq().  Do they need similar fixes?

>  	irq_domain_remove(pcie->msi.dev_domain);
>  
> -- 
> 2.34.1
>