diff mbox series

[3/5] btrfs-progs: fix fallthrough cases with proper attributes

Message ID 56794e8e6e0717c5fc981cfb3a96e4b1b5180818.1674797823.git.wqu@suse.com (mailing list archive)
State New, archived
Headers show
Series btrfs-progs: minor fixes for clang warnings | expand

Commit Message

Qu Wenruo Jan. 27, 2023, 5:41 a.m. UTC 
[FALSE ALERT]
Unlike gcc, clang doesn't really understand the comments, thus it's
reportings tons of fall through related errors:

  cmds/reflink.c:124:3: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
                  case 'r':
                  ^
  cmds/reflink.c:124:3: note: insert '__attribute__((fallthrough));' to silence this warning
                  case 'r':
                  ^
                  __attribute__((fallthrough));
  cmds/reflink.c:124:3: note: insert 'break;' to avoid fall-through
                  case 'r':
                  ^
                  break;

[CAUSE]
Although gcc is fine with /* fallthrough */ comments, clang is not.

[FIX]
So just introduce a fallthrough macro to handle the situation properly,
and use that macro instead.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 cmds/reflink.c             |  2 +-
 cmds/scrub.c               | 10 +++---
 common/format-output.c     |  2 +-
 common/parse-utils.c       | 12 +++----
 common/units.c             |  6 ++--
 crypto/xxhash.c            | 73 +++++++++++++++++++-------------------
 image/main.c               |  2 +-
 kerncompat.h               |  8 +++++
 kernel-shared/print-tree.c |  2 +-
 9 files changed, 63 insertions(+), 54 deletions(-)

Comments

David Sterba Feb. 9, 2023, 7:24 p.m. UTC | #1 
On Fri, Jan 27, 2023 at 01:41:16PM +0800, Qu Wenruo wrote:
> --- a/kerncompat.h
> +++ b/kerncompat.h
> @@ -227,6 +227,14 @@ static inline int mutex_is_locked(struct mutex *m)
>  #define __attribute_const__	__attribute__((__const__))
>  #endif
>  
> +/* To silent compilers like clang which doesn't understand comments. */
> +
> +#if __has_attribute(__fallthrough__)

The use of __has_attribute should be beihnd and ifdef
(https://gcc.gnu.org/onlinedocs/cpp/_005f_005fhas_005fattribute.html)
otherwise it fails, eg. on the reference Centos 7 build. Fixed.


> +# define fallthrough			__attribute__((__fallthrough__))
> +#else
> +# define fallthrough			do {} while (0)  /* fallthrough */
> +#endif
diff mbox series

Patch

diff --git a/cmds/reflink.c b/cmds/reflink.c
index 5ed9a12770e2..53f4784838c1 100644
--- a/cmds/reflink.c
+++ b/cmds/reflink.c
@@ -120,7 +120,7 @@  static int cmd_reflink_clone(const struct cmd_struct *cmd, int argc, char **argv
 		switch (c) {
 		case 's':
 			same_file = true;
-			/* fallthrough */
+			fallthrough;
 		case 'r':
 			range = malloc(sizeof(struct reflink_range));
 			if (!range) {
diff --git a/cmds/scrub.c b/cmds/scrub.c
index e6513b39f2bf..782a1310816b 100644
--- a/cmds/scrub.c
+++ b/cmds/scrub.c
@@ -602,7 +602,7 @@  again:
 			memset(p[curr], 0, sizeof(**p));
 			p[curr + 1] = NULL;
 			++state;
-			/* fall through */
+			fallthrough;
 		case 2: /* start of line, skip space */
 			while (isspace(l[i]) && i < avail) {
 				if (l[i] == '\n')
@@ -613,7 +613,7 @@  again:
 			    (!eof && !memchr(l + i, '\n', avail - i)))
 				goto again;
 			++state;
-			/* fall through */
+			fallthrough;
 		case 3: /* read fsid */
 			if (i == avail)
 				continue;
@@ -629,7 +629,7 @@  again:
 				_SCRUB_INVALID;
 			i += j + 1;
 			++state;
-			/* fall through */
+			fallthrough;
 		case 4: /* read dev id */
 			for (j = 0; isdigit(l[i + j]) && i+j < avail; ++j)
 				;
@@ -638,7 +638,7 @@  again:
 			p[curr]->devid = atoll(&l[i]);
 			i += j + 1;
 			++state;
-			/* fall through */
+			fallthrough;
 		case 5: /* read key/value pair */
 			ret = 0;
 			_SCRUB_KVREAD(ret, &i, data_extents_scrubbed, avail, l,
@@ -682,7 +682,7 @@  again:
 			if (ret != 1)
 				_SCRUB_INVALID;
 			++state;
-			/* fall through */
+			fallthrough;
 		case 6: /* after number */
 			if (l[i] == '|')
 				state = 5;
diff --git a/common/format-output.c b/common/format-output.c
index c7e021b58f2c..18993ad66636 100644
--- a/common/format-output.c
+++ b/common/format-output.c
@@ -74,7 +74,7 @@  static void print_escaped(const char *str)
 		case '"':
 		case '\\':
 			putchar('\\');
-			/* fallthrough */
+			fallthrough;
 		default:
 			putchar(*str);
 		}
diff --git a/common/parse-utils.c b/common/parse-utils.c
index f16b7aac1b3b..bb3c2bbf366a 100644
--- a/common/parse-utils.c
+++ b/common/parse-utils.c
@@ -184,22 +184,22 @@  u64 parse_size_from_string(const char *s)
 		switch (c) {
 		case 'e':
 			mult *= 1024;
-			/* fallthrough */
+			fallthrough;
 		case 'p':
 			mult *= 1024;
-			/* fallthrough */
+			fallthrough;
 		case 't':
 			mult *= 1024;
-			/* fallthrough */
+			fallthrough;
 		case 'g':
 			mult *= 1024;
-			/* fallthrough */
+			fallthrough;
 		case 'm':
 			mult *= 1024;
-			/* fallthrough */
+			fallthrough;
 		case 'k':
 			mult *= 1024;
-			/* fallthrough */
+			fallthrough;
 		case 'b':
 			break;
 		default:
diff --git a/common/units.c b/common/units.c
index 698dc1d0508e..8d708cddc03e 100644
--- a/common/units.c
+++ b/common/units.c
@@ -89,15 +89,15 @@  int pretty_size_snprintf(u64 size, char *str, size_t str_size, unsigned unit_mod
 	case UNITS_TBYTES:
 		base *= mult;
 		num_divs++;
-		/* fallthrough */
+		fallthrough;
 	case UNITS_GBYTES:
 		base *= mult;
 		num_divs++;
-		/* fallthrough */
+		fallthrough;
 	case UNITS_MBYTES:
 		base *= mult;
 		num_divs++;
-		/* fallthrough */
+		fallthrough;
 	case UNITS_KBYTES:
 		num_divs++;
 		break;
diff --git a/crypto/xxhash.c b/crypto/xxhash.c
index c2f1be9f7449..7f7f3f74328c 100644
--- a/crypto/xxhash.c
+++ b/crypto/xxhash.c
@@ -116,6 +116,7 @@  static void* XXH_memcpy(void* dest, const void* src, size_t size) { return memcp
 #define XXH_STATIC_LINKING_ONLY
 #include "xxhash.h"
 
+#include "kerncompat.h"
 
 /* *************************************
 *  Compiler Specific Options
@@ -397,41 +398,41 @@  XXH32_finalize(U32 h32, const void* ptr, size_t len, XXH_alignment align)
     } else {
          switch(len&15) /* or switch(bEnd - p) */ {
            case 12:      PROCESS4;
-                         /* fallthrough */
+			 fallthrough;
            case 8:       PROCESS4;
-                         /* fallthrough */
+			 fallthrough;
            case 4:       PROCESS4;
                          return XXH32_avalanche(h32);
 
            case 13:      PROCESS4;
-                         /* fallthrough */
+			 fallthrough;
            case 9:       PROCESS4;
-                         /* fallthrough */
+			 fallthrough;
            case 5:       PROCESS4;
                          PROCESS1;
                          return XXH32_avalanche(h32);
 
            case 14:      PROCESS4;
-                         /* fallthrough */
+			 fallthrough;
            case 10:      PROCESS4;
-                         /* fallthrough */
+			 fallthrough;
            case 6:       PROCESS4;
                          PROCESS1;
                          PROCESS1;
                          return XXH32_avalanche(h32);
 
            case 15:      PROCESS4;
-                         /* fallthrough */
+			 fallthrough;
            case 11:      PROCESS4;
-                         /* fallthrough */
+			 fallthrough;
            case 7:       PROCESS4;
-                         /* fallthrough */
+			 fallthrough;
            case 3:       PROCESS1;
-                         /* fallthrough */
+			 fallthrough;
            case 2:       PROCESS1;
-                         /* fallthrough */
+			 fallthrough;
            case 1:       PROCESS1;
-                         /* fallthrough */
+			 fallthrough;
            case 0:       return XXH32_avalanche(h32);
         }
         XXH_ASSERT(0);
@@ -825,63 +826,63 @@  XXH64_finalize(U64 h64, const void* ptr, size_t len, XXH_alignment align)
     } else {
         switch(len & 31) {
            case 24: PROCESS8_64;
-                         /* fallthrough */
+		    fallthrough;
            case 16: PROCESS8_64;
-                         /* fallthrough */
+		    fallthrough;
            case  8: PROCESS8_64;
                     return XXH64_avalanche(h64);
 
            case 28: PROCESS8_64;
-                         /* fallthrough */
+		    fallthrough;
            case 20: PROCESS8_64;
-                         /* fallthrough */
+		    fallthrough;
            case 12: PROCESS8_64;
-                         /* fallthrough */
+		    fallthrough;
            case  4: PROCESS4_64;
                     return XXH64_avalanche(h64);
 
            case 25: PROCESS8_64;
-                         /* fallthrough */
+		    fallthrough;
            case 17: PROCESS8_64;
-                         /* fallthrough */
+		    fallthrough;
            case  9: PROCESS8_64;
                     PROCESS1_64;
                     return XXH64_avalanche(h64);
 
            case 29: PROCESS8_64;
-                         /* fallthrough */
+		    fallthrough;
            case 21: PROCESS8_64;
-                         /* fallthrough */
+		    fallthrough;
            case 13: PROCESS8_64;
-                         /* fallthrough */
+		    fallthrough;
            case  5: PROCESS4_64;
                     PROCESS1_64;
                     return XXH64_avalanche(h64);
 
            case 26: PROCESS8_64;
-                         /* fallthrough */
+		    fallthrough;
            case 18: PROCESS8_64;
-                         /* fallthrough */
+		    fallthrough;
            case 10: PROCESS8_64;
                     PROCESS1_64;
                     PROCESS1_64;
                     return XXH64_avalanche(h64);
 
            case 30: PROCESS8_64;
-                         /* fallthrough */
+		    fallthrough;
            case 22: PROCESS8_64;
-                         /* fallthrough */
+		    fallthrough;
            case 14: PROCESS8_64;
-                         /* fallthrough */
+		    fallthrough;
            case  6: PROCESS4_64;
                     PROCESS1_64;
                     PROCESS1_64;
                     return XXH64_avalanche(h64);
 
            case 27: PROCESS8_64;
-                         /* fallthrough */
+		    fallthrough;
            case 19: PROCESS8_64;
-                         /* fallthrough */
+		    fallthrough;
            case 11: PROCESS8_64;
                     PROCESS1_64;
                     PROCESS1_64;
@@ -889,19 +890,19 @@  XXH64_finalize(U64 h64, const void* ptr, size_t len, XXH_alignment align)
                     return XXH64_avalanche(h64);
 
            case 31: PROCESS8_64;
-                         /* fallthrough */
+		    fallthrough;
            case 23: PROCESS8_64;
-                         /* fallthrough */
+		    fallthrough;
            case 15: PROCESS8_64;
-                         /* fallthrough */
+		    fallthrough;
            case  7: PROCESS4_64;
-                         /* fallthrough */
+		    fallthrough;
            case  3: PROCESS1_64;
-                         /* fallthrough */
+		    fallthrough;
            case  2: PROCESS1_64;
-                         /* fallthrough */
+		    fallthrough;
            case  1: PROCESS1_64;
-                         /* fallthrough */
+		    fallthrough;
            case  0: return XXH64_avalanche(h64);
         }
     }
diff --git a/image/main.c b/image/main.c
index 8900297ebe1a..ecf464e5b0a2 100644
--- a/image/main.c
+++ b/image/main.c
@@ -1431,7 +1431,7 @@  static int restore_one_work(struct mdrestore_struct *mdres,
 			switch (ret) {
 			case Z_NEED_DICT:
 				ret = Z_DATA_ERROR;
-				__attribute__ ((fallthrough));
+				fallthrough;
 			case Z_DATA_ERROR:
 			case Z_MEM_ERROR:
 				goto out;
diff --git a/kerncompat.h b/kerncompat.h
index 6fb79ac88351..74383ed9ff6c 100644
--- a/kerncompat.h
+++ b/kerncompat.h
@@ -227,6 +227,14 @@  static inline int mutex_is_locked(struct mutex *m)
 #define __attribute_const__	__attribute__((__const__))
 #endif
 
+/* To silent compilers like clang which doesn't understand comments. */
+
+#if __has_attribute(__fallthrough__)
+# define fallthrough			__attribute__((__fallthrough__))
+#else
+# define fallthrough			do {} while (0)  /* fallthrough */
+#endif
+
 /**
  * __set_bit - Set a bit in memory
  * @nr: the bit to set
diff --git a/kernel-shared/print-tree.c b/kernel-shared/print-tree.c
index ba1caa88fcf1..534166283997 100644
--- a/kernel-shared/print-tree.c
+++ b/kernel-shared/print-tree.c
@@ -796,7 +796,7 @@  void print_objectid(FILE *stream, u64 objectid, u8 type)
 			fprintf(stream, "FIRST_CHUNK_TREE");
 			break;
 		}
-		/* fall-thru */
+		fallthrough;
 	default:
 		fprintf(stream, "%llu", (unsigned long long)objectid);
 	}