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[PATCH] ftrace/x86: Add comment on static function tracing

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There was a confusion between update_ftrace_function() and static
function tracing trampoline regarding 3rd parameter (ftrace_ops).
Add a comment for clarification.

Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 arch/x86/kernel/mcount_64.S | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kernel/mcount_64.S b/arch/x86/kernel/mcount_64.S
index 94ea120fa21f..87e1762e2bca 100644
--- a/arch/x86/kernel/mcount_64.S
+++ b/arch/x86/kernel/mcount_64.S
@@ -278,6 +278,12 @@ GLOBAL(ftrace_stub)
 	/* save_mcount_regs fills in first two parameters */
 	save_mcount_regs
 
+	/*
+	 * When DYNAMIC_FTRACE is not defined, ARCH_SUPPORTS_FTRACE_OPS is not
+	 * set (see include/asm/ftrace.h and include/linux/ftrace.h).  Only the
+	 * ip and parent ip are used and the list function is called when
+	 * function tracing is enabled.
+	 */
 	call   *ftrace_trace_function
 
 	restore_mcount_regs
-- 
2.6.2

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[PATCH] ftrace/x86: Add comment on static function tracing Namhyung Kim <namhyung@kernel.org> - 2015-11-17 01:50 +0100
  Re: [PATCH] ftrace/x86: Add comment on static function tracing Steven Rostedt <rostedt@goodmis.org> - 2015-11-17 03:10 +0100
  [tip:x86/urgent] x86/ftrace:   Add comment on static function tracing tip-bot for Namhyung Kim <tipbot@zytor.com> - 2015-11-19 11:20 +0100

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