[PATCH 1/2] dma-mapping: Protect dma_addressing_limited against NULL dma_mask

dma_addressing_limited() should not be called on a device with
a NULL dma_mask. If this occurs let's WARN_ON_ONCE and immediately
return. Existing call sites are updated separately.

Fixes: b866455423e0 ("dma-mapping: add a dma_addressing_limited helper")
Signed-off-by: Eric Auger <eric.auger@redhat.com>

---

v1 -> v2:
- add a WARN_ON_ONCE()
- reword the commit message
---
 include/linux/dma-mapping.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index e11b115dd0e4..ef0cf9537abc 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h

@@ -689,8 +689,9 @@ static inline int dma_coerce_mask_and_coherent(struct device *dev, u64 mask)
  */
 static inline bool dma_addressing_limited(struct device *dev)
 {
-	return min_not_zero(*dev->dma_mask, dev->bus_dma_mask) <
-		dma_get_required_mask(dev);
+	return WARN_ON_ONCE(!dev->dma_mask) ? false :
+		min_not_zero(*dev->dma_mask, dev->bus_dma_mask) <
+			dma_get_required_mask(dev);
 }
 
 #ifdef CONFIG_ARCH_HAS_SETUP_DMA_OPS

-- 
2.20.1