gru: check for valid vma

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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/misc/sgi-gru/grufault.c b/drivers/misc/sgi-gru/grufault.c
index ada7df7..7466234 100644 (file)
--- a/drivers/misc/sgi-gru/grufault.c
+++ b/drivers/misc/sgi-gru/grufault.c
@@ -90,19 +90,22 @@ static struct gru_thread_state *gru_alloc_locked_gts(unsigned long vaddr)
 {
        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;
 }