linux-kernel - [for-next][PATCH 03/10] ftrace: Return ENOTSUPP when DYNAMIC_FTRACE_WITH_DIRECT

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Date:   Sat, 23 Nov 2019 13:12:00 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org
Cc:     Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexei Starovoitov <ast@...nel.org>
Subject: [for-next][PATCH 03/10] ftrace: Return ENOTSUPP when DYNAMIC_FTRACE_WITH_DIRECT_CALLS is not
 configured

From: Alexei Starovoitov <alexei.starovoitov@...il.com>

When CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS is not set it's best to
have the stub functions return ENOTSUPP instead of ENODEV,
otherwise ENODEV is a valid error when ip is incorrect which is
indistinguishable from ftrace not compiled in.

Link: http://lkml.kernel.org/r/CAADnVQ+OzTikM9EhrfsC7NFsVYhATW1SVHxK64w3xn9qpk81pg@mail.gmail.com

Signed-off-by: Alexei Starovoitov <ast@...nel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
 include/linux/ftrace.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index dfaa37e1943d..af79b0f8cdc1 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -268,16 +268,16 @@ int ftrace_modify_direct_caller(struct ftrace_func_entry *entry,
 # define ftrace_direct_func_count 0
 static inline int register_ftrace_direct(unsigned long ip, unsigned long addr)
 {
-	return -ENODEV;
+	return -ENOTSUPP;
 }
 static inline int unregister_ftrace_direct(unsigned long ip, unsigned long addr)
 {
-	return -ENODEV;
+	return -ENOTSUPP;
 }
 static inline int modify_ftrace_direct(unsigned long ip,
 				       unsigned long old_addr, unsigned long new_addr)
 {
-	return -ENODEV;
+	return -ENOTSUPP;
 }
 static inline struct ftrace_direct_func *ftrace_find_direct_func(unsigned long addr)
 {
-- 
2.24.0