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Code Issues Releases Activity

The recent PCI resource allocation fixes exposed a bug where the same

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BAR could be allocated twice by different children of a vgapci0 device.
To fix this, change the vgapci0 device to track references on its associated
resources so that they are only allocated once from the parent PCI bus and
released when no children are using them.  Previously this leaked a small
amount of KVA on at least some architectures.
This commit is contained in:
John Baldwin 2009-03-04 21:04:52 +00:00
parent dfb11ef895
commit e8b145c2ba
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=189373
1 changed files with 59 additions and 0 deletions
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59
sys/dev/pci/vga_pci.c
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@ -42,12 +42,20 @@ __FBSDID("$FreeBSD$");
#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
@ -130,7 +138,27 @@ static struct resource *
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));
}
@ -138,6 +166,37 @@ static int
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));
}