[PATCH] powerpc/powernv: fix variable "c" set but not used

[Qian Cai]

The commit 58629c0dc349 ("powerpc/powernv/npu: Fault user page into the
hypervisor's pagetable") introduced a variable "c" to be used in
__get_user() and __get_user_nocheck() which need to stay as macros for
performance reasons, and "c" is not actually used in
pnv_npu2_handle_fault(),

arch/powerpc/platforms/powernv/npu-dma.c: In function 'pnv_npu2_handle_fault':
arch/powerpc/platforms/powernv/npu-dma.c:1122:7: warning: variable 'c'
set but not used [-Wunused-but-set-variable]

Fixed it by appending the __maybe_unused attribute, so compilers would
ignore it.

Signed-off-by: Qian Cai <c...@lca.pw>
---
 arch/powerpc/platforms/powernv/npu-dma.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/powernv/npu-dma.c 
b/arch/powerpc/platforms/powernv/npu-dma.c
index 495550432f3d..5bbe59573ee6 100644
--- a/arch/powerpc/platforms/powernv/npu-dma.c
+++ b/arch/powerpc/platforms/powernv/npu-dma.c
@@ -1119,7 +1119,8 @@ int pnv_npu2_handle_fault(struct npu_context *context, 
uintptr_t *ea,
        int i, is_write;
        struct page *page[1];
        const char __user *u;
-       char c;
+       /* To silence a -Wunused-but-set-variable warning. */
+       char c __maybe_unused;
 
        /* mmap_sem should be held so the struct_mm must be present */
        struct mm_struct *mm = context->mm;
-- 
2.20.1 (Apple Git-117)