[RFC 1/6] powerpc/mm/book3s64: unlock RCU before returning from mm_iommu_is_devmem()

["Ritesh Harjani (IBM)" <ritesh.list@gmail.com>]

Clang's context analysis reports:
  iommu_api.c:380:1: error: __ctx_lock_RCU 'RCU' is not held on every path through here [-Werror,-Wthread-safety-analysis]

mm_iommu_is_devmem() takes the RCU read lock to walk the preregistered
device-memory list. On a match it returned true from inside the loop and
skipped rcu_read_unlock(). Hence fix it.

Fixes: b5952f8125ae ("powerpc/mm/book3s64/iommu: fix some RCU-list locks")
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
---
 arch/powerpc/mm/book3s64/iommu_api.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/mm/book3s64/iommu_api.c b/arch/powerpc/mm/book3s64/iommu_api.c
index 60d00c9e7f19..56d9aa6cc8e2 100644
--- a/arch/powerpc/mm/book3s64/iommu_api.c
+++ b/arch/powerpc/mm/book3s64/iommu_api.c
@@ -356,6 +356,7 @@ bool mm_iommu_is_devmem(struct mm_struct *mm, unsigned long hpa,
 {
 	struct mm_iommu_table_group_mem_t *mem;
 	unsigned long end;
+	bool ret = false;
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, next) {
@@ -371,12 +372,13 @@ bool mm_iommu_is_devmem(struct mm_struct *mm, unsigned long hpa,
 			 * and the caller needs to distinguish this situation.
 			 */
 			*size = min(1UL << pageshift, end - hpa);
-			return true;
+			ret = true;
+			break;
 		}
 	}
 	rcu_read_unlock();
 
-	return false;
+	return ret;
 }
 EXPORT_SYMBOL_GPL(mm_iommu_is_devmem);
 
-- 
2.39.5