linux-kernel - [PATCH] printk: Don't bother using LOG_CPU_MAX_BUF

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Date:	Fri,  8 Aug 2014 17:20:44 +0200
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	"Luis R. Rodriguez" <mcgrof@...e.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org,
	Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: [PATCH] printk: Don't bother using LOG_CPU_MAX_BUF_SHIFT on !SMP

When configuring a uniprocessor kernel, don't bother the user with an
irrelevant LOG_CPU_MAX_BUF_SHIFT question, and don't build the unused
code.

Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
---
 init/Kconfig           | 1 +
 kernel/printk/printk.c | 7 ++++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/init/Kconfig b/init/Kconfig
index a5f8bc426f7c..aa6f87c04728 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -822,6 +822,7 @@ config LOG_BUF_SHIFT
 
 config LOG_CPU_MAX_BUF_SHIFT
 	int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
+	depends on SMP
 	range 0 21
 	default 12 if !BASE_SMALL
 	default 0 if BASE_SMALL
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index de1a6bb6861d..d5dc94028166 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -267,7 +267,6 @@ static u32 clear_idx;
 #define LOG_ALIGN __alignof__(struct printk_log)
 #endif
 #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
-#define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT)
 static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
 static char *log_buf = __log_buf;
 static u32 log_buf_len = __LOG_BUF_LEN;
@@ -846,6 +845,9 @@ static int __init log_buf_len_setup(char *str)
 }
 early_param("log_buf_len", log_buf_len_setup);
 
+#ifdef CONFIG_SMP
+#define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT)
+
 static void __init log_buf_add_cpu(void)
 {
 	unsigned int cpu_extra;
@@ -872,6 +874,9 @@ static void __init log_buf_add_cpu(void)
 
 	log_buf_len_update(cpu_extra + __LOG_BUF_LEN);
 }
+#else /* !CONFIG_SMP */
+static inline void log_buf_add_cpu(void) {}
+#endif /* CONFIG_SMP */
 
 void __init setup_log_buf(int early)
 {
-- 
1.9.1

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