linux-kernel - [PATCH] profile: hide unused functions when !CONFIG_PROC

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Date:	Mon, 25 Jan 2016 16:39:12 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-arm-kernel@...ts.infradead.org,
	Arnd Bergmann <arnd@...db.de>,
	Vlastimil Babka <vbabka@...e.cz>,
	Robin Holt <robinmholt@...il.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Christoph Lameter <cl@...ux.com>, Tejun Heo <tj@...nel.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] profile: hide unused functions when !CONFIG_PROC_FS

A couple of functions and variables in the profile implementation are
used only on SMP systems by the procfs code, but are unused if
either procfs is disabled or in uniprocessor kernels. gcc prints
a harmless warning about the unused symbols:

kernel/profile.c:243:13: error: 'profile_flip_buffers' defined but not used [-Werror=unused-function]
 static void profile_flip_buffers(void)
             ^
kernel/profile.c:266:13: error: 'profile_discard_flip_buffers' defined but not used [-Werror=unused-function]
 static void profile_discard_flip_buffers(void)
             ^
kernel/profile.c:330:12: error: 'profile_cpu_callback' defined but not used [-Werror=unused-function]
 static int profile_cpu_callback(struct notifier_block *info,
            ^

This adds further #ifdef to the file, to annotate exactly in
which cases they are used. I have done several thousand ARM randconfig
kernels with this patch applied and no longer get any warnings in
this file.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 kernel/profile.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/profile.c b/kernel/profile.c
index 99513e1160e5..9cd8e18e6f18 100644
--- a/kernel/profile.c
+++ b/kernel/profile.c
@@ -44,7 +44,7 @@ int prof_on __read_mostly;
 EXPORT_SYMBOL_GPL(prof_on);
 
 static cpumask_var_t prof_cpu_mask;
-#ifdef CONFIG_SMP
+#if defined(CONFIG_SMP) && defined(CONFIG_PROC_FS)
 static DEFINE_PER_CPU(struct profile_hit *[2], cpu_profile_hits);
 static DEFINE_PER_CPU(int, cpu_profile_flip);
 static DEFINE_MUTEX(profile_flip_mutex);
@@ -201,7 +201,7 @@ int profile_event_unregister(enum profile_type type, struct notifier_block *n)
 }
 EXPORT_SYMBOL_GPL(profile_event_unregister);
 
-#ifdef CONFIG_SMP
+#if defined(CONFIG_SMP) && defined(CONFIG_PROC_FS)
 /*
  * Each cpu has a pair of open-addressed hashtables for pending
  * profile hits. read_profile() IPI's all cpus to request them
-- 
2.7.0