linux-kernel - [PATCH v2 1/3] printk: nbcon: Export console_is

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Message-Id: <20250811-nbcon-kgdboc-v2-1-c7c72bcdeaf6@suse.com>
Date: Mon, 11 Aug 2025 10:32:45 -0300
From: Marcos Paulo de Souza <mpdesouza@...e.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 Petr Mladek <pmladek@...e.com>, Steven Rostedt <rostedt@...dmis.org>, 
 John Ogness <john.ogness@...utronix.de>, 
 Sergey Senozhatsky <senozhatsky@...omium.org>, 
 Jason Wessel <jason.wessel@...driver.com>, 
 Daniel Thompson <danielt@...nel.org>, 
 Douglas Anderson <dianders@...omium.org>
Cc: linux-kernel@...r.kernel.org, kgdb-bugreport@...ts.sourceforge.net, 
 Marcos Paulo de Souza <mpdesouza@...e.com>
Subject: [PATCH v2 1/3] printk: nbcon: Export console_is_usable

The helper will be used on KDB code in the next commits.

Signed-off-by: Marcos Paulo de Souza <mpdesouza@...e.com>
---
 include/linux/console.h  | 44 ++++++++++++++++++++++++++++++++++++++++++++
 kernel/printk/internal.h | 41 -----------------------------------------
 2 files changed, 44 insertions(+), 41 deletions(-)

diff --git a/include/linux/console.h b/include/linux/console.h
index 8f10d0a85bb4536e4b0dda4e8ccbdf87978bbb4a..67af483574727c00eea1d5a1eacc994755c92607 100644
--- a/include/linux/console.h
+++ b/include/linux/console.h
@@ -605,6 +605,48 @@ extern bool nbcon_can_proceed(struct nbcon_write_context *wctxt);
 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);
+
+/*
+ * Check if the given console is currently capable and allowed to print
+ * records. Note that this function does not consider the current context,
+ * which can also play a role in deciding if @con can be used to print
+ * records.
+ */
+static inline bool console_is_usable(struct console *con, short flags, bool use_atomic)
+{
+	if (!(flags & CON_ENABLED))
+		return false;
+
+	if ((flags & CON_SUSPENDED))
+		return false;
+
+	if (flags & CON_NBCON) {
+		/* The write_atomic() callback is optional. */
+		if (use_atomic && !con->write_atomic)
+			return false;
+
+		/*
+		 * For the !use_atomic case, @printk_kthreads_running is not
+		 * checked because the write_thread() callback is also used
+		 * via the legacy loop when the printer threads are not
+		 * available.
+		 */
+	} else {
+		if (!con->write)
+			return false;
+	}
+
+	/*
+	 * Console drivers may assume that per-cpu resources have been
+	 * allocated. So unless they're explicitly marked as being able to
+	 * cope (CON_ANYTIME) don't call them until this CPU is officially up.
+	 */
+	if (!cpu_online(raw_smp_processor_id()) && !(flags & CON_ANYTIME))
+		return false;
+
+	return true;
+}
+
 #else
 static inline void nbcon_cpu_emergency_enter(void) { }
 static inline void nbcon_cpu_emergency_exit(void) { }
@@ -612,6 +654,8 @@ static inline bool nbcon_can_proceed(struct nbcon_write_context *wctxt) { return
 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) { }
+static inline bool console_is_usable(struct console *con, short flags,
+				     bool use_atomic) { return false; }
 #endif
 
 extern int console_set_on_cmdline;
diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
index ef282001f200fdbbacae3171932bf9f049037a85..077927ed56c5f7ae22f76be4635a4b4614387de8 100644
--- a/kernel/printk/internal.h
+++ b/kernel/printk/internal.h
@@ -112,47 +112,6 @@ bool nbcon_kthread_create(struct console *con);
 void nbcon_kthread_stop(struct console *con);
 void nbcon_kthreads_wake(void);
 
-/*
- * Check if the given console is currently capable and allowed to print
- * records. Note that this function does not consider the current context,
- * which can also play a role in deciding if @con can be used to print
- * records.
- */
-static inline bool console_is_usable(struct console *con, short flags, bool use_atomic)
-{
-	if (!(flags & CON_ENABLED))
-		return false;
-
-	if ((flags & CON_SUSPENDED))
-		return false;
-
-	if (flags & CON_NBCON) {
-		/* The write_atomic() callback is optional. */
-		if (use_atomic && !con->write_atomic)
-			return false;
-
-		/*
-		 * For the !use_atomic case, @printk_kthreads_running is not
-		 * checked because the write_thread() callback is also used
-		 * via the legacy loop when the printer threads are not
-		 * available.
-		 */
-	} else {
-		if (!con->write)
-			return false;
-	}
-
-	/*
-	 * Console drivers may assume that per-cpu resources have been
-	 * allocated. So unless they're explicitly marked as being able to
-	 * cope (CON_ANYTIME) don't call them until this CPU is officially up.
-	 */
-	if (!cpu_online(raw_smp_processor_id()) && !(flags & CON_ANYTIME))
-		return false;
-
-	return true;
-}
-
 /**
  * nbcon_kthread_wake - Wake up a console printing thread
  * @con:	Console to operate on

-- 
2.50.0