[PATCH v2 15/17] printk/percpu: Define printk_func when printk is not defined

[Wang Long <long.wanglong@huawei.com>]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

commit 04b74b27c2941e5d62120f6fee3a0a9388a30613 upstream.

To avoid include hell, the per_cpu variable printk_func was declared
in percpu.h. But it is only defined if printk is defined.

As users of printk may also use the printk_func variable, it needs to
be defined even if CONFIG_PRINTK is not.

Also add a printk.h include in percpu.h just to be safe.

Link: http://lkml.kernel.org/r/20141121183215.01ba539c@canb.auug.org.au

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
[wanglong: backport to 3.10 stable
- adjust context
]
Signed-off-by: Wang Long <long.wanglong@huawei.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/percpu.h | 1 +
 include/linux/printk.h | 4 ++--
 kernel/printk.c        | 3 +++
 3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index bb1d29c..60e425e 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -4,6 +4,7 @@
 #include <linux/preempt.h>
 #include <linux/smp.h>
 #include <linux/cpumask.h>
+#include <linux/printk.h>
 #include <linux/pfn.h>
 #include <linux/init.h>
 
diff --git a/include/linux/printk.h b/include/linux/printk.h
index ebc7f3e..14b4098 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -106,6 +106,8 @@ static inline __printf(1, 2) __cold
 void early_printk(const char *s, ...) { }
 #endif
 
+typedef int(*printk_func_t)(const char *fmt, va_list args);
+
 #ifdef CONFIG_PRINTK
 asmlinkage __printf(5, 0)
 int vprintk_emit(int facility, int level,
@@ -144,8 +146,6 @@ extern int kptr_restrict;
 
 extern void wake_up_klogd(void);
 
-typedef int(*printk_func_t)(const char *fmt, va_list args);
-
 void log_buf_kexec_setup(void);
 void __init setup_log_buf(int early);
 void dump_stack_set_arch_desc(const char *fmt, ...);
diff --git a/kernel/printk.c b/kernel/printk.c
index 6a81232..70cdb0f 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1746,6 +1746,9 @@ static size_t msg_print_text(const struct log *msg, enum log_flags prev,
 			     bool syslog, char *buf, size_t size) { return 0; }
 static size_t cont_print_text(char *text, size_t size) { return 0; }
 
+/* Still needs to be defined for users */
+DEFINE_PER_CPU(printk_func_t, printk_func);
+
 #endif /* CONFIG_PRINTK */
 
 #ifdef CONFIG_EARLY_PRINTK
-- 
1.8.3.4