Re: [PATCH v3 1/2] PCI: Add pci_remove_irq_domain() helper

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Mon, Jul 15, 2024 at 01:48:53PM +0200, Marek Behún wrote:
> Add a helper function pci_remove_irq_domain() for disposing all
> interrupt mappings of an IRQ domain and then removing said IRQ domain.
> 
> As explained in the attached link, the PCI INTX interrupt may be shared,
> and so the PCI device drivers do not dispose mapped interrupts when they
> are unbound from a device, since other devices may be still using those
> mapped interrupts. Thus the interrupts must be disposed by the PCI
> controller driver when the IRQ domain is being removed.
> 
> This function may be used by PCI controller drivers that wish to be
> removable / modular.
> 
> Link: https://lore.kernel.org/linux-pci/878qy5rrq7.ffs@tglx/
> Signed-off-by: Marek Behún <kabel@kernel.org>

Thomas shared the diff leading to this patch. Shouldn't you give some credit to
him?

For the patch though,

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

- Mani

> ---
>  drivers/pci/irq.c | 21 +++++++++++++++++++++
>  drivers/pci/pci.h |  7 +++++++
>  2 files changed, 28 insertions(+)
> 
> diff --git a/drivers/pci/irq.c b/drivers/pci/irq.c
> index 4555630be9ec..30c8d930016a 100644
> --- a/drivers/pci/irq.c
> +++ b/drivers/pci/irq.c
> @@ -11,6 +11,7 @@
>  #include <linux/errno.h>
>  #include <linux/export.h>
>  #include <linux/interrupt.h>
> +#include <linux/irqdomain.h>
>  #include <linux/pci.h>
>  
>  #include "pci.h"
> @@ -259,6 +260,26 @@ bool pci_check_and_unmask_intx(struct pci_dev *dev)
>  }
>  EXPORT_SYMBOL_GPL(pci_check_and_unmask_intx);
>  
> +#ifdef CONFIG_IRQ_DOMAIN
> +/**
> + * pci_remove_irq_domain - dispose all IRQ mappings and remove IRQ domain
> + * @domain: the IRQ domain to be removed
> + *
> + * Disposes all IRQ mappings of a given IRQ domain before removing the domain.
> + */
> +void pci_remove_irq_domain(struct irq_domain *domain)
> +{
> +	for (irq_hw_number_t i = 0; i < domain->hwirq_max; i++) {
> +		unsigned int virq = irq_find_mapping(domain, i);
> +
> +		if (virq)
> +			irq_dispose_mapping(virq);
> +	}
> +
> +	irq_domain_remove(domain);
> +}
> +#endif
> +
>  /**
>   * pcibios_penalize_isa_irq - penalize an ISA IRQ
>   * @irq: ISA IRQ to penalize
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index fd44565c4756..1ba6a6f418ac 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -170,6 +170,13 @@ void pci_no_msi(void);
>  static inline void pci_no_msi(void) { }
>  #endif
>  
> +struct irq_domain;
> +#ifdef CONFIG_IRQ_DOMAIN
> +void pci_remove_irq_domain(struct irq_domain *domain);
> +#else
> +static inline void pci_remove_irq_domain(struct irq_domain *domain) { }
> +#endif
> +
>  void pci_realloc_get_opt(char *);
>  
>  static inline int pci_no_d1d2(struct pci_dev *dev)
> -- 
> 2.44.2
> 

-- 
மணிவண்ணன் சதாசிவம்