Hi

On Fri, Sep 13, 2013 at 2:33 PM, Prarit Bhargava prarit@redhat.com wrote:

Fix uninitialized warning.

drivers/gpu/drm/ttm/ttm_object.c: In function ‘ttm_base_object_lookup’: drivers/gpu/drm/ttm/ttm_object.c:213:10: error: ‘base’ may be used uninitialized in this function [-Werror=maybe-uninitialized] kref_put(&base->refcount, ttm_release_base); ^ drivers/gpu/drm/ttm/ttm_object.c:221:26: note: ‘base’ was declared here struct ttm_base_object *base;

Signed-off-by: Prarit Bhargava prarit@redhat.com Cc: David Airlie airlied@linux.ie Cc: rclark@redhat.com

Did some research on that, another fix is:

diff --git a/drivers/gpu/drm/ttm/ttm_object.c b/drivers/gpu/drm/ttm/ttm_object.c index 58a5f32..6b7f7b7 100644 --- a/drivers/gpu/drm/ttm/ttm_object.c +++ b/drivers/gpu/drm/ttm/ttm_object.c @@ -228,7 +228,10 @@ struct ttm_base_object *ttm_base_object_lookup(struct ttm_object_file *tfile, if (likely(ret == 0)) { base = drm_hash_entry(hash, struct ttm_base_object, hash); ret = kref_get_unless_zero(&base->refcount) ? 0 : -EINVAL; + } else { + ret = -EINVAL; } + rcu_read_unlock();

if (unlikely(ret != 0))

Looks totally stupid but also silences the warning. In fact, the warning is triggered by rcu_read_unlock(); and only if PROVE_LOCKING and DEBUG_LOCK_ALLOC are enabled. And it's related to the IP-size of the rcu_read_unlock() path.

I'd actually prefer "buf = NULL;" and an extended bail-out condition: if (unlikely(ret != 0 || !buf)) but it's not my decision, so: Reviewed-by: David Herrmann dh.herrmann@gmail.com

Cheers David

---

drivers/gpu/drm/ttm/ttm_object.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/ttm/ttm_object.c b/drivers/gpu/drm/ttm/ttm_object.c index 58a5f32..a868176 100644 --- a/drivers/gpu/drm/ttm/ttm_object.c +++ b/drivers/gpu/drm/ttm/ttm_object.c @@ -218,7 +218,7 @@ struct ttm_base_object *ttm_base_object_lookup(struct ttm_object_file *tfile, uint32_t key) { struct ttm_object_device *tdev = tfile->tdev;

•   struct ttm_base_object *base;
  

•   struct ttm_base_object *uninitialized_var(base);
    struct drm_hash_item *hash;
    int ret;
  
  

-- 1.7.9.3

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