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authorJan Beulich <jbeulich@novell.com>2008-06-18 09:28:00 +0100
committerDave Airlie <airlied@redhat.com>2008-06-19 09:56:16 +1000
commitda503fa60b84d5945deb3ab74efdd0bec61df4a1 (patch)
tree9883d28cabdab419567a2c0689d06c938460eaa1 /drivers/char/agp/backend.c
parentdcd981a77b2b35d169656d4b9cee208096ed7ccf (diff)
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.c16
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);
}
}