dma-mapping: avoid potential unused data compilation warning

commit c9b19ea
Author: Marek Szyprowski <[email protected]>
Date: Tue Apr 15 09:56:59 2025 +0200

    dma-mapping: avoid potential unused data compilation warning

    When CONFIG_NEED_DMA_MAP_STATE is not defined, dma-mapping clients might
    report unused data compilation warnings for dma_unmap_*() calls
    arguments. Redefine macros for those calls to let compiler to notice that
    it is okay when the provided arguments are not used.

    Reported-by: Andy Shevchenko <[email protected]>
    Suggested-by: Jakub Kicinski <[email protected]>
    Signed-off-by: Marek Szyprowski <[email protected]>
    Tested-by: Andy Shevchenko <[email protected]>
    Link: https://lore.kernel.org/r/[email protected]

(cherry picked from commit c9b19ea)
Signed-off-by: Jerry Snitselaar <[email protected]>
Upstream-Status: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
JIRA: https://issues.redhat.com/browse/RHEL-89891

Author: snits

include/linux/dma-mapping.h

@@ -629,10 +629,14 @@ static inline int dma_mmap_wc(struct device *dev,
 #else
 #define DEFINE_DMA_UNMAP_ADDR(ADDR_NAME)
 #define DEFINE_DMA_UNMAP_LEN(LEN_NAME)
-#define dma_unmap_addr(PTR, ADDR_NAME)           (0)
-#define dma_unmap_addr_set(PTR, ADDR_NAME, VAL)  do { } while (0)
-#define dma_unmap_len(PTR, LEN_NAME)             (0)
-#define dma_unmap_len_set(PTR, LEN_NAME, VAL)    do { } while (0)
+#define dma_unmap_addr(PTR, ADDR_NAME)           \
+	({ typeof(PTR) __p __maybe_unused = PTR; 0; })
+#define dma_unmap_addr_set(PTR, ADDR_NAME, VAL)  \
+	do { typeof(PTR) __p __maybe_unused = PTR; } while (0)
+#define dma_unmap_len(PTR, LEN_NAME)             \
+	({ typeof(PTR) __p __maybe_unused = PTR; 0; })
+#define dma_unmap_len_set(PTR, LEN_NAME, VAL)    \
+	do { typeof(PTR) __p __maybe_unused = PTR; } while (0)
 #endif
 
 #endif /* _LINUX_DMA_MAPPING_H */