On Thu, Jun 28, 2007 at 06:14:27PM -0700, Li, Shaohua wrote:
>
>
> ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.22-
> >rc6/2.6.22-rc6-mm1/
> >>
> >>> +intel-iommu-dmar-detection-and-parsing-logic.patch
[..]
> >
> >I took a picture of it, looks like the backtrace is:
> >
> >NULL pointer dereference at 024
> >EIP:dmar_table_init+0x11
> >intel_iommu_init+0x30
> >pci_iommu_init+0xe
> >kernel_init+0x16e
> >
> >Presumably something is NULL in dmar_table_init that wasn't expected to
> >be.. I would guess it likely crashes on any system without an Intel
> >IOMMU in it.
Yup, that is correct.
> How about something like below?
>
>
> int __init dmar_table_init(void)
> {
> + if (!dmar_tbl)
> + return -ENODEV;
> parse_dmar_table();
why not check for NULL in the function where it touched?
Also when there are no DMAR devices we need the below
printk on the console.
> if (list_empty(&dmar_drhd_units)) {
> printk(KERN_ERR PREFIX "No DMAR devices found\n");
> return -ENODEV;
> }
> return 0;
> }
Here is the revised patch of the above.
Andrew, please add this fix to
+intel-iommu-dmar-detection-and-parsing-logic.patch
------------------------------------------------
Check for dmar_tbl pointer as this can be NULL on
systems with no Intel VT-d support.
Signed-off-by: Anil S Keshavamurthy <[email protected]>
---
drivers/pci/dmar.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
Index: linux-2.6.22-rc4-mm2/drivers/pci/dmar.c
===================================================================
--- linux-2.6.22-rc4-mm2.orig/drivers/pci/dmar.c 2007-06-29 07:43:43.000000000 -0700
+++ linux-2.6.22-rc4-mm2/drivers/pci/dmar.c 2007-06-29 07:46:25.000000000 -0700
@@ -260,6 +260,8 @@
int ret = 0;
dmar = (struct acpi_table_dmar *)dmar_tbl;
+ if (!dmar)
+ return -ENODEV;
if (!dmar->width) {
printk (KERN_WARNING PREFIX "Zero: Invalid DMAR haw\n");
@@ -301,7 +303,7 @@
parse_dmar_table();
if (list_empty(&dmar_drhd_units)) {
- printk(KERN_ERR PREFIX "No DMAR devices found\n");
+ printk(KERN_INFO PREFIX "No DMAR devices found\n");
return -ENODEV;
}
return 0;
-
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