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Date:   Fri, 14 Feb 2020 11:00:35 -0500
From:   Sasha Levin <>
Cc:     David Sterba <>,
        Josh Poimboeuf <>,
        Randy Dunlap <>,
        Sasha Levin <>,
Subject: [PATCH AUTOSEL 5.4 385/459] btrfs: separate definition of assertion failure handlers

From: David Sterba <>

[ Upstream commit 68c467cbb2f389b6c933e235bce0d1756fc8cc34 ]

There's a report where objtool detects unreachable instructions, eg.:

  fs/btrfs/ctree.o: warning: objtool: btrfs_search_slot()+0x2d4: unreachable instruction

This seems to be a false positive due to compiler version. The cause is
in the ASSERT macro implementation that does the conditional check as

To avoid that, use the ifdefs directly.

There are still 2 reports that aren't fixed:

  fs/btrfs/extent_io.o: warning: objtool: __set_extent_bit()+0x71f: unreachable instruction
  fs/btrfs/relocation.o: warning: objtool: find_data_references()+0x4e0: unreachable instruction

Co-developed-by: Josh Poimboeuf <>
Signed-off-by: Josh Poimboeuf <>
Reported-by: Randy Dunlap <>
Signed-off-by: David Sterba <>
Signed-off-by: Sasha Levin <>
 fs/btrfs/ctree.h | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 290ca193c6c0f..169075550a5a2 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3107,17 +3107,21 @@ do {								\
 	rcu_read_unlock();					\
 } while (0)
-static inline void assfail(const char *expr, const char *file, int line)
+__cold __noreturn
+static inline void assertfail(const char *expr, const char *file, int line)
-		pr_err("assertion failed: %s, in %s:%d\n", expr, file, line);
-		BUG();
-	}
+	pr_err("assertion failed: %s, in %s:%d\n", expr, file, line);
+	BUG();
-#define ASSERT(expr)	\
-	(likely(expr) ? (void)0 : assfail(#expr, __FILE__, __LINE__))
+#define ASSERT(expr)						\
+	(likely(expr) ? (void)0 : assertfail(#expr, __FILE__, __LINE__))
+static inline void assertfail(const char *expr, const char* file, int line) { }
+#define ASSERT(expr)	(void)(expr)
  * Use that for functions that are conditionally exported for sanity tests but

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