[ 3.5.y.z extended stable ] Patch "drm/ttm: fix the tt_populated check in ttm_tt_destroy()" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    drm/ttm: fix the tt_populated check in ttm_tt_destroy()

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 167d5fb00b21b95460674693842b20584d84729d Mon Sep 17 00:00:00 2001
From: Ben Skeggs <bskeggs at redhat.com>
Date: Tue, 17 Sep 2013 14:21:15 +1000
Subject: [PATCH] drm/ttm: fix the tt_populated check in ttm_tt_destroy()

commit 182b17c8dc4e83aab000ce86587b6810e515da87 upstream.

After a vmalloc failure in ttm_dma_tt_alloc_page_directory(),
ttm_dma_tt_init() will call ttm_tt_destroy() to cleanup, and end up
inside the driver's unpopulate() hook when populate() has never yet
been called.

On nouveau, the first issue to be hit because of this is that
dma_address[] may be a NULL pointer.  After working around this,
ttm_pool_unpopulate() may potentially hit the same issue with
the pages[] array.

It seems to make more sense to avoid calling unpopulate on already
unpopulated TTMs than to add checks to all the implementations.

Signed-off-by: Ben Skeggs <bskeggs at redhat.com>
Reviewed-by: Thomas Hellstrom <thellstrom at vmware.com>
Cc: Jerome Glisse <jglisse at redhat.com>
Signed-off-by: Dave Airlie <airlied at redhat.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/gpu/drm/ttm/ttm_tt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c
index fa09daf..ea10bbe 100644
--- a/drivers/gpu/drm/ttm/ttm_tt.c
+++ b/drivers/gpu/drm/ttm/ttm_tt.c
@@ -170,7 +170,7 @@ void ttm_tt_destroy(struct ttm_tt *ttm)
 		ttm_tt_unbind(ttm);
 	}

-	if (likely(ttm->pages != NULL)) {
+	if (ttm->state == tt_unbound) {
 		ttm->bdev->driver->ttm_tt_unpopulate(ttm);
 	}

--
1.8.3.2