linux-kernel - [PATCH] x86/ftrace: avoid an unused-function warning

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Date:   Mon,  4 Mar 2019 21:07:39 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>, x86@...nel.org
Cc:     Arnd Bergmann <arnd@...db.de>, "H. Peter Anvin" <hpa@...or.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] x86/ftrace: avoid an unused-function warning

Depending on the configuration, ftrace_jmp_replace() sometimes
has no callers at all, since one of the users was removed:

arch/x86/kernel/ftrace.c:669:23: error: 'ftrace_jmp_replace' defined but not used [-Werror=unused-function]

Rather than trying to figure out the correct #ifdef check for this
time, just mark it __maybe_unused and let the compiler drop it
silently.

Fixes: d2a68c4effd8 ("x86/ftrace: Do not call function graph from dynamic trampolines")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 arch/x86/kernel/ftrace.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 3e3789c8f8e1..905056240411 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -665,8 +665,7 @@ int __init ftrace_dyn_arch_init(void)
 	return 0;
 }
 
-#if defined(CONFIG_X86_64) || defined(CONFIG_FUNCTION_GRAPH_TRACER)
-static unsigned char *ftrace_jmp_replace(unsigned long ip, unsigned long addr)
+static __maybe_unused unsigned char *ftrace_jmp_replace(unsigned long ip, unsigned long addr)
 {
 	static union ftrace_code_union calc;
 
@@ -679,7 +678,6 @@ static unsigned char *ftrace_jmp_replace(unsigned long ip, unsigned long addr)
 	 */
 	return calc.code;
 }
-#endif
 
 /* Currently only x86_64 supports dynamic trampolines */
 #ifdef CONFIG_X86_64
-- 
2.20.0