diff --git a/lib/zstd/Makefile b/lib/zstd/Makefile
index 7920cbb..f5d778e 100644
--- a/lib/zstd/Makefile
+++ b/lib/zstd/Makefile
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
 obj-$(CONFIG_ZSTD_COMPRESS) += zstd_compress.o
 obj-$(CONFIG_ZSTD_DECOMPRESS) += zstd_decompress.o
 
diff --git a/lib/zstd/bitstream.h b/lib/zstd/bitstream.h
index a826b99..3a49784 100644
--- a/lib/zstd/bitstream.h
+++ b/lib/zstd/bitstream.h
@@ -259,10 +259,15 @@
 		bitD->bitContainer = *(const BYTE *)(bitD->start);
 		switch (srcSize) {
 		case 7: bitD->bitContainer += (size_t)(((const BYTE *)(srcBuffer))[6]) << (sizeof(bitD->bitContainer) * 8 - 16);
+			/* fall through */
 		case 6: bitD->bitContainer += (size_t)(((const BYTE *)(srcBuffer))[5]) << (sizeof(bitD->bitContainer) * 8 - 24);
+			/* fall through */
 		case 5: bitD->bitContainer += (size_t)(((const BYTE *)(srcBuffer))[4]) << (sizeof(bitD->bitContainer) * 8 - 32);
+			/* fall through */
 		case 4: bitD->bitContainer += (size_t)(((const BYTE *)(srcBuffer))[3]) << 24;
+			/* fall through */
 		case 3: bitD->bitContainer += (size_t)(((const BYTE *)(srcBuffer))[2]) << 16;
+			/* fall through */
 		case 2: bitD->bitContainer += (size_t)(((const BYTE *)(srcBuffer))[1]) << 8;
 		default:;
 		}
diff --git a/lib/zstd/compress.c b/lib/zstd/compress.c
index f9166cf..5e0b670 100644
--- a/lib/zstd/compress.c
+++ b/lib/zstd/compress.c
@@ -3182,6 +3182,7 @@
 				zcs->outBuffFlushedSize = 0;
 				zcs->stage = zcss_flush; /* pass-through to flush stage */
 			}
+			/* fall through */
 
 		case zcss_flush: {
 			size_t const toFlush = zcs->outBuffContentSize - zcs->outBuffFlushedSize;
diff --git a/lib/zstd/decompress.c b/lib/zstd/decompress.c
index b178467..269ee9a 100644
--- a/lib/zstd/decompress.c
+++ b/lib/zstd/decompress.c
@@ -1768,6 +1768,7 @@
 			return 0;
 		}
 		dctx->expected = 0; /* not necessary to copy more */
+		/* fall through */
 
 	case ZSTDds_decodeFrameHeader:
 		memcpy(dctx->headerBuffer + ZSTD_frameHeaderSize_prefix, src, dctx->expected);
@@ -2375,7 +2376,7 @@
 			}
 			zds->stage = zdss_read;
 		}
-		/* pass-through */
+		/* fall through */
 
 		case zdss_read: {
 			size_t const neededInSize = ZSTD_nextSrcSizeToDecompress(zds->dctx);
@@ -2404,6 +2405,7 @@
 			zds->stage = zdss_load;
 			/* pass-through */
 		}
+		/* fall through */
 
 		case zdss_load: {
 			size_t const neededInSize = ZSTD_nextSrcSizeToDecompress(zds->dctx);
@@ -2436,6 +2438,7 @@
 				/* pass-through */
 			}
 		}
+		/* fall through */
 
 		case zdss_flush: {
 			size_t const toFlushSize = zds->outEnd - zds->outStart;
diff --git a/lib/zstd/huf_compress.c b/lib/zstd/huf_compress.c
index 40055a7..e727812 100644
--- a/lib/zstd/huf_compress.c
+++ b/lib/zstd/huf_compress.c
@@ -556,7 +556,9 @@
 	n = srcSize & ~3; /* join to mod 4 */
 	switch (srcSize & 3) {
 	case 3: HUF_encodeSymbol(&bitC, ip[n + 2], CTable); HUF_FLUSHBITS_2(&bitC);
+		/* fall through */
 	case 2: HUF_encodeSymbol(&bitC, ip[n + 1], CTable); HUF_FLUSHBITS_1(&bitC);
+		/* fall through */
 	case 1: HUF_encodeSymbol(&bitC, ip[n + 0], CTable); HUF_FLUSHBITS(&bitC);
 	case 0:
 	default:;
diff --git a/lib/zstd/mem.h b/lib/zstd/mem.h
index 3a0f34c..93d7a2c 100644
--- a/lib/zstd/mem.h
+++ b/lib/zstd/mem.h
@@ -27,7 +27,7 @@
 /*-****************************************
 *  Compiler specifics
 ******************************************/
-#define ZSTD_STATIC static __inline __attribute__((unused))
+#define ZSTD_STATIC static inline
 
 /*-**************************************************************
 *  Basic Types