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| author | Jan Beulich <jbeulich@novell.com> | 2008-06-18 09:28:00 +0100 |
|---|---|---|
| committer | Dave Airlie <airlied@redhat.com> | 2008-06-19 09:56:16 +1000 |
| commit | da503fa60b84d5945deb3ab74efdd0bec61df4a1 (patch) | |
| tree | 9883d28cabdab419567a2c0689d06c938460eaa1 /drivers/char/agp/backend.c | |
| parent | dcd981a77b2b35d169656d4b9cee208096ed7ccf (diff) | |
| download | lwn-da503fa60b84d5945deb3ab74efdd0bec61df4a1.tar.gz lwn-da503fa60b84d5945deb3ab74efdd0bec61df4a1.zip | |
agp: two-stage page destruction issue
besides it apparently being useful only in 2.6.24 (the changes in 2.6.25
really mean that it could be converted back to a single-stage mechanism),
I'm seeing an issue in Xen Dom0 kernels, which is caused by the calling
of gart_to_virt() in the second stage invocations of the destroy function.
I think that besides this being a real issue with Xen (where
unmap_page_from_agp() is not just a page table attribute change), this
also is invalid from a theoretical perspective: One should not assume that
gart_to_virt() is still valid after unmapping a page. So minimally (keeping
the 2-stage mechanism) a patch like the one below would be needed.
Jan
Signed-off-by: Dave Airlie <airlied@redhat.com>
Diffstat (limited to 'drivers/char/agp/backend.c')
| -rw-r--r-- | drivers/char/agp/backend.c | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/drivers/char/agp/backend.c b/drivers/char/agp/backend.c index b1bdd015165c..1ec87104e68c 100644 --- a/drivers/char/agp/backend.c +++ b/drivers/char/agp/backend.c @@ -188,10 +188,10 @@ static int agp_backend_initialize(struct agp_bridge_data *bridge) err_out: if (bridge->driver->needs_scratch_page) { - bridge->driver->agp_destroy_page(gart_to_virt(bridge->scratch_page_real), - AGP_PAGE_DESTROY_UNMAP); - bridge->driver->agp_destroy_page(gart_to_virt(bridge->scratch_page_real), - AGP_PAGE_DESTROY_FREE); + void *va = gart_to_virt(bridge->scratch_page_real); + + bridge->driver->agp_destroy_page(va, AGP_PAGE_DESTROY_UNMAP); + bridge->driver->agp_destroy_page(va, AGP_PAGE_DESTROY_FREE); } if (got_gatt) bridge->driver->free_gatt_table(bridge); @@ -215,10 +215,10 @@ static void agp_backend_cleanup(struct agp_bridge_data *bridge) if (bridge->driver->agp_destroy_page && bridge->driver->needs_scratch_page) { - bridge->driver->agp_destroy_page(gart_to_virt(bridge->scratch_page_real), - AGP_PAGE_DESTROY_UNMAP); - bridge->driver->agp_destroy_page(gart_to_virt(bridge->scratch_page_real), - AGP_PAGE_DESTROY_FREE); + void *va = gart_to_virt(bridge->scratch_page_real); + + bridge->driver->agp_destroy_page(va, AGP_PAGE_DESTROY_UNMAP); + bridge->driver->agp_destroy_page(va, AGP_PAGE_DESTROY_FREE); } } |