[patch 41/96] intel-agp: fix a panic with 1M of shared memory, no GTT entries

Greg KH
2009-03-14T00:32:49Z

[-- Attachment #1: intel-agp-fix-a-panic-with-1m-of-shared-memory-no-gtt-entries.patch --]
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2.6.27-stable review patch. If anyone has any objections, please let us know.

------------------

From: Lubomir Rintel <lkundrak@v3.sk>

commit 9c1e8a4ebcc04226cb6f3a1bf1d72f4cafd6b089 upstream.

When GTT size is equal to amount of video memory, the amount of GTT
entries is computed lower than zero, which is invalid and leads to
off-by-one error in intel_i915_configure()

Originally posted here:
http://bugzilla.kernel.org/show_bug.cgi?id=12539
http://bugzilla.redhat.com/show_bug.cgi?id=445592

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Cc: Lubomir Rintel <lkundrak@v3.sk>
Cc: Dave Airlie <airlied@linux.ie>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/char/agp/intel-agp.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

--- a/drivers/char/agp/intel-agp.c
+++ b/drivers/char/agp/intel-agp.c
@@ -633,13 +633,15 @@ static void intel_i830_init_gtt_entries(
break;
}
}
- if (gtt_entries > 0)
+ if (gtt_entries > 0) {
dev_info(&agp_bridge->dev->dev, "detected %dK %s memory\n",
gtt_entries / KB(1), local ? "local" : "stolen");
- else
+ gtt_entries /= KB(4);
+ } else {
dev_info(&agp_bridge->dev->dev,
"no pre-allocated video memory detected\n");
- gtt_entries /= KB(4);
+ gtt_entries = 0;
+ }

intel_private.gtt_entries = gtt_entries;
}