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: NGeert Uytterhoeven <geert@linux-m68k.org>
Acked-by: NLuis R. Rodriguez <mcgrof@suse.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

init/Kconfig

@@ -838,6 +838,7 @@ 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

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;
@@ -852,6 +851,9 @@ 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;
@@ -878,6 +880,9 @@ 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)
 {