Re: [Xen-devel] [PATCH for-4.5] call xc_domain_irq_permission before xc_domain_irq_permission

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Mon, 1 Dec 2014, Stefano Stabellini wrote:
> xc_physdev_unmap_pirq might revoke the permission to map the irq from
> the domain causing the following xc_domain_irq_permission call to fail
> and return error (domain_pirq_to_irq returns 0).
> 
> Call xc_domain_irq_permission first to prevent this from happening
> (xc_physdev_unmap_pirq calls irq_deny_access, that doesn't fail if the
> permission is already removed).
> 
> This is a simple bug fix and I think should go in 4.5.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>

This patch didn't actually make it into 4.5, but I think it should have.
We could at least apply to master now.


> diff --git a/tools/libxl/libxl_pci.c b/tools/libxl/libxl_pci.c
> index 316643c..904d255 100644
> --- a/tools/libxl/libxl_pci.c
> +++ b/tools/libxl/libxl_pci.c
> @@ -1288,14 +1290,14 @@ skip1:
>              goto out;
>          }
>          if ((fscanf(f, "%u", &irq) == 1) && irq) {
> -            rc = xc_physdev_unmap_pirq(ctx->xch, domid, irq);
> -            if (rc < 0) {
> -                LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, 
> "xc_physdev_unmap_pirq irq=%d", irq);
> -            }
>              rc = xc_domain_irq_permission(ctx->xch, domid, irq, 0);
>              if (rc < 0) {
>                  LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, 
> "xc_domain_irq_permission irq=%d", irq);
>              }
> +            rc = xc_physdev_unmap_pirq(ctx->xch, domid, irq);
> +            if (rc < 0) {
> +                LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, 
> "xc_physdev_unmap_pirq irq=%d", irq);
> +            }
>          }
>          fclose(f);
>      }
> 

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