linux-kernel - [PATCH] tracing/ring-buffer: hide unused last_boot

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Message-Id: <20240719102640.718554-1-arnd@kernel.org>
Date: Fri, 19 Jul 2024 12:26:33 +0200
From: Arnd Bergmann <arnd@...nel.org>
To: Steven Rostedt <rostedt@...dmis.org>,
	Masami Hiramatsu <mhiramat@...nel.org>
Cc: Arnd Bergmann <arnd@...db.de>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Zheng Yejian <zhengyejian1@...wei.com>,
	Vincent Donnefort <vdonnefort@...gle.com>,
	Huang Yiwei <quic_hyiwei@...cinc.com>,
	"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@...il.com>,
	linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org
Subject: [PATCH] tracing/ring-buffer: hide unused last_boot_fops

From: Arnd Bergmann <arnd@...db.de>

This variable is used only in an #ifdef, which causes a W=1 warning
with some compilers:

kernel/trace/trace.c:7570:37: error: 'last_boot_fops' defined but not used [-Werror=unused-const-variable=]
 7570 | static const struct file_operations last_boot_fops = {

Guard this one with the same #ifdef.

Fixes: 7a1d1e4b9639 ("tracing/ring-buffer: Add last_boot_info file to boot instance")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
Alternatively it could be marked as __maybe_unused, but I tried to follow
the style used in this file.
---
 kernel/trace/trace.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 5462fb10ff64..6ab24213d496 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6913,6 +6913,7 @@ tracing_total_entries_read(struct file *filp, char __user *ubuf,
 	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
 }
 
+#ifdef CONFIG_TRACER_SNAPSHOT
 static ssize_t
 tracing_last_boot_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
 {
@@ -6927,6 +6928,7 @@ tracing_last_boot_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t
 
 	return simple_read_from_buffer(ubuf, cnt, ppos, buf, seq_buf_used(&seq));
 }
+#endif
 
 static int tracing_buffer_meta_open(struct inode *inode, struct file *filp)
 {
@@ -7567,12 +7569,14 @@ static const struct file_operations trace_time_stamp_mode_fops = {
 	.release	= tracing_single_release_tr,
 };
 
+#ifdef CONFIG_TRACER_SNAPSHOT
 static const struct file_operations last_boot_fops = {
 	.open		= tracing_open_generic_tr,
 	.read		= tracing_last_boot_read,
 	.llseek		= generic_file_llseek,
 	.release	= tracing_release_generic_tr,
 };
+#endif
 
 #ifdef CONFIG_TRACER_SNAPSHOT
 static const struct file_operations snapshot_fops = {
-- 
2.39.2