This function will be used in the next patch to allow a driver to set
both the message and message length of a nbcon_write_context. This is
necessary because the function also initializes the ->unsafe_takeover
struct member. By using this helper we ensure that the struct is
initialized correctly.

Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
---
 include/linux/console.h | 4 ++++
 kernel/printk/nbcon.c   | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/linux/console.h b/include/linux/console.h
index b34c5a0b86303e2fb4583fa467d8be43761cf756..e0fc2608bd9d6a886f5ddc56d26f19b21ae8663d 100644
--- a/include/linux/console.h
+++ b/include/linux/console.h
@@ -602,6 +602,8 @@ static inline bool console_is_registered(const struct console *con)
 extern void nbcon_cpu_emergency_enter(void);
 extern void nbcon_cpu_emergency_exit(void);
 extern bool nbcon_can_proceed(struct nbcon_write_context *wctxt);
+extern void nbcon_write_context_set_buf(struct nbcon_write_context *wctxt,
+					char *buf, unsigned int len);
 extern bool nbcon_enter_unsafe(struct nbcon_write_context *wctxt);
 extern bool nbcon_exit_unsafe(struct nbcon_write_context *wctxt);
 extern void nbcon_reacquire_nobuf(struct nbcon_write_context *wctxt);
@@ -654,6 +656,8 @@ static inline bool console_is_usable(struct console *con, short flags, bool use_
 static inline void nbcon_cpu_emergency_enter(void) { }
 static inline void nbcon_cpu_emergency_exit(void) { }
 static inline bool nbcon_can_proceed(struct nbcon_write_context *wctxt) { return false; }
+static inline void nbcon_write_context_set_buf(struct nbcon_write_context *wctxt,
+					       char *buf, unsigned int len) { }
 static inline bool nbcon_enter_unsafe(struct nbcon_write_context *wctxt) { return false; }
 static inline bool nbcon_exit_unsafe(struct nbcon_write_context *wctxt) { return false; }
 static inline void nbcon_reacquire_nobuf(struct nbcon_write_context *wctxt) { }
diff --git a/kernel/printk/nbcon.c b/kernel/printk/nbcon.c
index 6e4641350fe8985438f53bcd32f3adf72d9d6835..2492b14bd272562378c4cdb465eea2269638e127 100644
--- a/kernel/printk/nbcon.c
+++ b/kernel/printk/nbcon.c
@@ -854,7 +854,7 @@ static bool __nbcon_context_update_unsafe(struct nbcon_context *ctxt, bool unsaf
 	return nbcon_context_can_proceed(ctxt, &cur);
 }
 
-static void nbcon_write_context_set_buf(struct nbcon_write_context *wctxt,
+void nbcon_write_context_set_buf(struct nbcon_write_context *wctxt,
 					char *buf, unsigned int len)
 {
 	struct nbcon_context *ctxt = &ACCESS_PRIVATE(wctxt, ctxt);

-- 
2.51.0

On 2025-09-30, Marcos Paulo de Souza <mpdesouza@suse.com> wrote:
> diff --git a/kernel/printk/nbcon.c b/kernel/printk/nbcon.c
> index 6e4641350fe8985438f53bcd32f3adf72d9d6835..2492b14bd272562378c4cdb465eea2269638e127 100644
> --- a/kernel/printk/nbcon.c
> +++ b/kernel/printk/nbcon.c
> @@ -854,7 +854,7 @@ static bool __nbcon_context_update_unsafe(struct nbcon_context *ctxt, bool unsaf
>  	return nbcon_context_can_proceed(ctxt, &cur);
>  }
>  
> -static void nbcon_write_context_set_buf(struct nbcon_write_context *wctxt,
> +void nbcon_write_context_set_buf(struct nbcon_write_context *wctxt,
>  					char *buf, unsigned int len)

Could we also update the whitespace on the 2nd line? And it would all
fit on one line if you want.

John