[Patch 14/29] GRU - Check for valid vma

[steiner@sgi.com]

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From: Jack Steiner <steiner@sgi.com>

Fix bug caused by failure to allocate a GRU gts structure. The
old code failed to handle the case where the vma was invalid.

Signed-off-by: Jack Steiner <steiner@sgi.com>

---
 drivers/misc/sgi-gru/grufault.c |   21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

Index: linux/drivers/misc/sgi-gru/grufault.c
===================================================================
--- linux.orig/drivers/misc/sgi-gru/grufault.c	2009-11-20 09:32:31.000000000 -0600
+++ linux/drivers/misc/sgi-gru/grufault.c	2009-11-20 09:32:33.000000000 -0600
@@ -90,19 +90,22 @@ static struct gru_thread_state *gru_allo
 {
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
-	struct gru_thread_state *gts = NULL;
+	struct gru_thread_state *gts = ERR_PTR(-EINVAL);
 
 	down_write(&mm->mmap_sem);
 	vma = gru_find_vma(vaddr);
-	if (vma)
-		gts = gru_alloc_thread_state(vma, TSID(vaddr, vma));
-	if (!IS_ERR(gts)) {
-		mutex_lock(&gts->ts_ctxlock);
-		downgrade_write(&mm->mmap_sem);
-	} else {
-		up_write(&mm->mmap_sem);
-	}
+	if (!vma)
+		goto err;
 
+	gts = gru_alloc_thread_state(vma, TSID(vaddr, vma));
+	if (IS_ERR(gts))
+		goto err;
+	mutex_lock(&gts->ts_ctxlock);
+	downgrade_write(&mm->mmap_sem);
+	return gts;
+
+err:
+	up_write(&mm->mmap_sem);
 	return gts;
 }