devres: fix possible use after free

devres uses the pointer value as key after it's freed, which is safe but
triggers spurious use-after-free warnings on some static analysis tools.
Rearrange code to avoid such warnings.

Signed-off-by: Maxin B. John <maxin.john@gmail.com>
Reviewed-by: Rolf Eike Beer <eike-kernel@sf-tec.de>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/dmapool.c b/mm/dmapool.c
index 03bf3bb..fbb58e3 100644
--- a/mm/dmapool.c
+++ b/mm/dmapool.c
@@ -500,7 +500,7 @@
 {
 	struct device *dev = pool->dev;
 
-	dma_pool_destroy(pool);
 	WARN_ON(devres_destroy(dev, dmam_pool_release, dmam_pool_match, pool));
+	dma_pool_destroy(pool);
 }
 EXPORT_SYMBOL(dmam_pool_destroy);