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Message-Id: <20250713-nbcon-kgdboc-v1-1-51eccd9247a8@suse.com>
Date: Sun, 13 Jul 2025 02:09:18 -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 1/2] printk: nbcon: Export console_is_usage and other nbcon
symbols
Function nbcon_context_try_acquire, nbcon_context_relase and
console_is_usable are going to be used in the next patch.
Signed-off-by: Marcos Paulo de Souza <mpdesouza@...e.com>
---
include/linux/console.h | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
kernel/printk/internal.h | 41 -----------------------------------------
kernel/printk/nbcon.c | 4 ++--
3 files changed, 50 insertions(+), 43 deletions(-)
diff --git a/include/linux/console.h b/include/linux/console.h
index 8f10d0a85bb4536e4b0dda4e8ccbdf87978bbb4a..d5398b4be4f7ce8d1642b919952710431b53a8ad 100644
--- a/include/linux/console.h
+++ b/include/linux/console.h
@@ -599,19 +599,67 @@ static inline bool console_is_registered(const struct console *con)
hlist_for_each_entry(con, &console_list, node)
#ifdef CONFIG_PRINTK
+extern bool nbcon_context_try_acquire(struct nbcon_context *ctxt);
+extern void nbcon_context_release(struct nbcon_context *ctxt);
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 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 bool nbcon_context_try_acquire(struct nbcon_context *ctxt) { }
+static inline void nbcon_context_release(struct nbcon_context *ctxt) { }
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 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 48a24e7b309db20fdd7419f7aeda68ea7c79fd80..4ad51a98690b43fd2383a0c6e70ac4da68c34da3 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
diff --git a/kernel/printk/nbcon.c b/kernel/printk/nbcon.c
index fd12efcc4aeda8883773d9807bc215f6e5cdf71a..b95030018472493b1019932c3d1d92c1abd044ee 100644
--- a/kernel/printk/nbcon.c
+++ b/kernel/printk/nbcon.c
@@ -568,7 +568,7 @@ static struct printk_buffers panic_nbcon_pbufs;
* in an unsafe state. Otherwise, on success the caller may assume
* the console is not in an unsafe state.
*/
-static bool nbcon_context_try_acquire(struct nbcon_context *ctxt)
+bool nbcon_context_try_acquire(struct nbcon_context *ctxt)
{
unsigned int cpu = smp_processor_id();
struct console *con = ctxt->console;
@@ -648,7 +648,7 @@ static bool nbcon_owner_matches(struct nbcon_state *cur, int expected_cpu,
* nbcon_context_release - Release the console
* @ctxt: The nbcon context from nbcon_context_try_acquire()
*/
-static void nbcon_context_release(struct nbcon_context *ctxt)
+void nbcon_context_release(struct nbcon_context *ctxt)
{
unsigned int cpu = smp_processor_id();
struct console *con = ctxt->console;
--
2.50.0
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