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authorDave Airlie <airlied@redhat.com>2007-10-15 10:19:16 +1000
committerDave Airlie <airlied@optimus.(none)>2007-10-15 10:32:15 +1000
commita2721e998ede079db10f65e4b42310f79dc8f135 (patch)
tree32963c9bf40f3e0871d4d549bb6c3cf13abbb24c /drivers/char/agp/generic.c
parent23fd50450a34f2558070ceabb0bfebc1c9604af5 (diff)
AGP fix race condition between unmapping and freeing pages
With Andi's clflush fixup, we were getting hangs on server exit, flushing the mappings after freeing each page helped. This showed up a race condition where the pages after being freed could be reused before the agp mappings had been flushed. Flushing after each single page is a bad thing for future drm work, so make the page destroy a two pass unmapping all the pages, flushing the mappings, and then destroying the pages. Signed-off-by: Dave Airlie <airlied@linux.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'drivers/char/agp/generic.c')
-rw-r--r--drivers/char/agp/generic.c19
1 files changed, 13 insertions, 6 deletions
diff --git a/drivers/char/agp/generic.c b/drivers/char/agp/generic.c
index 3db4f4076ed..64b2f6d7059 100644
--- a/drivers/char/agp/generic.c
+++ b/drivers/char/agp/generic.c
@@ -195,9 +195,12 @@ void agp_free_memory(struct agp_memory *curr)
}
if (curr->page_count != 0) {
for (i = 0; i < curr->page_count; i++) {
- curr->bridge->driver->agp_destroy_page(gart_to_virt(curr->memory[i]));
+ curr->bridge->driver->agp_destroy_page(gart_to_virt(curr->memory[i]), AGP_PAGE_DESTROY_UNMAP);
}
flush_agp_mappings();
+ for (i = 0; i < curr->page_count; i++) {
+ curr->bridge->driver->agp_destroy_page(gart_to_virt(curr->memory[i]), AGP_PAGE_DESTROY_FREE);
+ }
}
agp_free_key(curr->key);
agp_free_page_array(curr);
@@ -1176,7 +1179,7 @@ void *agp_generic_alloc_page(struct agp_bridge_data *bridge)
EXPORT_SYMBOL(agp_generic_alloc_page);
-void agp_generic_destroy_page(void *addr)
+void agp_generic_destroy_page(void *addr, int flags)
{
struct page *page;
@@ -1184,10 +1187,14 @@ void agp_generic_destroy_page(void *addr)
return;
page = virt_to_page(addr);
- unmap_page_from_agp(page);
- put_page(page);
- free_page((unsigned long)addr);
- atomic_dec(&agp_bridge->current_memory_agp);
+ if (flags & AGP_PAGE_DESTROY_UNMAP)
+ unmap_page_from_agp(page);
+
+ if (flags & AGP_PAGE_DESTROY_FREE) {
+ put_page(page);
+ free_page((unsigned long)addr);
+ atomic_dec(&agp_bridge->current_memory_agp);
+ }
}
EXPORT_SYMBOL(agp_generic_destroy_page);