Re: pci regression: "panic: resource_list_alloc: resource entry is busy"

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John Baldwin wrote:

> Probably at some point the agp and drm drivers for Intel will be merged which
> would fix this, but this patch should help for now.  We used to be leaking
> a small portion of KVA due to this problem before.
> 
> --- //depot/vendor/freebsd/src/sys/dev/pci/vga_pci.c	2008/09/19 19:15:30
> +++ //depot/user/jhb/acpipci/dev/pci/vga_pci.c	2009/03/04 15:32:08
> _at__at_ -42,12 +42,20 _at__at_
>  #include <sys/bus.h>
>  #include <sys/kernel.h>
>  #include <sys/module.h>
> +#include <sys/rman.h>
> +#include <sys/systm.h>
>  
>  #include <dev/pci/pcireg.h>
>  #include <dev/pci/pcivar.h>
>  
> +struct vga_resource {
> +	struct resource	*vr_res;
> +	int	vr_refs;
> +};
> +
>  struct vga_pci_softc {
>  	device_t	vga_msi_child;	/* Child driver using MSI. */
> +	struct vga_resource vga_res[PCIR_MAX_BAR_0 + 1];
>  };
>  
>  static int
> _at__at_ -130,7 +138,27 _at__at_
>  vga_pci_alloc_resource(device_t dev, device_t child, int type, int *rid,
>      u_long start, u_long end, u_long count, u_int flags)
>  {
> +	struct vga_pci_softc *sc;
> +	int bar;
>  
> +	switch (type) {
> +	case SYS_RES_MEMORY:
> +	case SYS_RES_IOPORT:
> +		/*
> +		 * For BARs, we cache the resource so that we only allocate it
> +		 * from the PCI bus once.
> +		 */
> +		bar = PCI_RID2BAR(*rid);
> +		if (bar < 0 || bar > PCIR_MAX_BAR_0)
> +			return (NULL);
> +		sc = device_get_softc(dev);
> +		if (sc->vga_res[bar].vr_res == NULL)
> +			sc->vga_res[bar].vr_res = bus_alloc_resource(dev, type,
> +			    rid, start, end, count, flags);
> +		if (sc->vga_res[bar].vr_res != NULL)
> +			sc->vga_res[bar].vr_refs++;
> +		return (sc->vga_res[bar].vr_res);
> +	}
>  	return (bus_alloc_resource(dev, type, rid, start, end, count, flags));
>  }
>  
> _at__at_ -138,6 +166,37 _at__at_
>  vga_pci_release_resource(device_t dev, device_t child, int type, int rid,
>      struct resource *r)
>  {
> +	struct vga_pci_softc *sc;
> +	int bar, error;
> +
> +	switch (type) {
> +	case SYS_RES_MEMORY:
> +	case SYS_RES_IOPORT:
> +		/*
> +		 * For BARs, we release the resource from the PCI bus
> +		 * when the last child reference goes away.
> +		 */
> +		bar = PCI_RID2BAR(rid);
> +		if (bar < 0 || bar > PCIR_MAX_BAR_0)
> +			return (EINVAL);
> +		sc = device_get_softc(dev);
> +		if (sc->vga_res[bar].vr_res == NULL)
> +			return (EINVAL);
> +		KASSERT(sc->vga_res[bar].vr_res == r,
> +		    ("vga_pci resource mismatch"));
> +		if (sc->vga_res[bar].vr_refs > 1) {
> +			sc->vga_res[bar].vr_refs--;
> +			return (0);
> +		}
> +		KASSERT(sc->vga_res[bar].vr_refs > 0,
> +		    ("vga_pci resource reference count underflow"));
> +		error = bus_release_resource(dev, type, rid, r);
> +		if (error == 0) {
> +			sc->vga_res[bar].vr_res = NULL;
> +			sc->vga_res[bar].vr_refs = 0;
> +		}
> +		return (error);
> +	}
>  
>  	return (bus_release_resource(dev, type, rid, r));
>  }
> 

This works perfectly, thanks! :-)

	Michael
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