commit b8ac0e25895734744ec3f6fb3326ebca032c9ad6
author Xiaoming Ni <nixiaoming@huawei.com> Thu Nov 18 14:01:04 2021 -0800
committer Luis Chamberlain <mcgrof@kernel.org> Wed Nov 24 14:52:24 2021 -0800
tree 92a9c3171ffac858e31f9059816b3c7373cc90d9
parent 46964d75b7937c2762edc22c68e5c33c1a16bece

printk: fix build warning when CONFIG_PRINTK=n

build warning when CONFIG_PRINTK=n
	kernel/printk/printk.c:175:5: warning: no previous prototype for
	 'devkmsg_sysctl_set_loglvl' [-Wmissing-prototypes]

devkmsg_sysctl_set_loglvl() is only used in sysctl.c when CONFIG_PRINTK=y,
but it participates in the build when CONFIG_PRINTK=n. So add compile
dependency CONFIG_PRINTK=y && CONFIG_SYSCTL=y to fix the build warning.

Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

include/linux/printk.h

diff --git a/include/linux/printk.h b/include/linux/printk.h
index 9497f6b..1522df2 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -183,10 +183,6 @@ extern bool printk_timed_ratelimit(unsigned long *caller_jiffies,
 extern int printk_delay_msec;
 extern int dmesg_restrict;
 
-extern int
-devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write, void *buf,
-			  size_t *lenp, loff_t *ppos);
-
 extern void wake_up_klogd(void);
 
 char *log_buf_addr_get(void);

kernel/printk/internal.h

diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
index 6b1c4b3..d947ca6 100644
--- a/kernel/printk/internal.h
+++ b/kernel/printk/internal.h
@@ -6,6 +6,8 @@
 
 #if defined(CONFIG_PRINTK) && defined(CONFIG_SYSCTL)
 void __init printk_sysctl_init(void);
+int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write,
+			      void *buffer, size_t *lenp, loff_t *ppos);
 #else
 #define printk_sysctl_init() do { } while (0)
 #endif

kernel/printk/printk.c

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index dbb4408..55722b9 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -171,7 +171,7 @@ static int __init control_devkmsg(char *str)
 __setup("printk.devkmsg=", control_devkmsg);
 
 char devkmsg_log_str[DEVKMSG_STR_MAX_SIZE] = "ratelimit";
-
+#if defined(CONFIG_PRINTK) && defined(CONFIG_SYSCTL)
 int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write,
 			      void *buffer, size_t *lenp, loff_t *ppos)
 {
@@ -210,6 +210,7 @@ int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write,
 
 	return 0;
 }
+#endif /* CONFIG_PRINTK && CONFIG_SYSCTL */
 
 /* Number of registered extended console drivers. */
 static int nr_ext_console_drivers;