[PATCH printk v2 06/18] printk: nbcon: Add context to console_is_usable()

[John Ogness <john.ogness@linutronix.de>]

The nbcon consoles have two callbacks to be used for different
contexts. In order to determine if an nbcon console is usable,
console_is_usable() needs to know if it is a context that will
use the write_atomic() callback or the write_thread() callback.

Add an extra parameter @use_atomic to specify this.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
---
 kernel/printk/internal.h | 16 ++++++++++------
 kernel/printk/nbcon.c    |  8 ++++----
 kernel/printk/printk.c   |  6 ++++--
 3 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
index 38680c6b2b39..243d3d3bc889 100644
--- a/kernel/printk/internal.h
+++ b/kernel/printk/internal.h
@@ -100,7 +100,7 @@ void nbcon_kthread_create(struct console *con);
  * 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)
+static inline bool console_is_usable(struct console *con, short flags, bool use_atomic)
 {
 	if (!(flags & CON_ENABLED))
 		return false;
@@ -109,10 +109,13 @@ static inline bool console_is_usable(struct console *con, short flags)
 		return false;
 
 	if (flags & CON_NBCON) {
-		if (!con->write_atomic)
-			return false;
-		if (!con->write_thread)
-			return false;
+		if (use_atomic) {
+			if (!con->write_atomic)
+				return false;
+		} else {
+			if (!con->write_thread)
+				return false;
+		}
 	} else {
 		if (!con->write)
 			return false;
@@ -177,7 +180,8 @@ static inline void nbcon_atomic_flush_pending(void) { }
 static inline bool nbcon_legacy_emit_next_record(struct console *con, bool *handover,
 						 int cookie) { return false; }
 
-static inline bool console_is_usable(struct console *con, short flags) { return false; }
+static inline bool console_is_usable(struct console *con, short flags,
+				     bool use_atomic) { return false; }
 
 #endif /* CONFIG_PRINTK */
 
diff --git a/kernel/printk/nbcon.c b/kernel/printk/nbcon.c
index 19f0db6945e4..4200953d368e 100644
--- a/kernel/printk/nbcon.c
+++ b/kernel/printk/nbcon.c
@@ -967,7 +967,7 @@ static bool nbcon_kthread_should_wakeup(struct console *con, struct nbcon_contex
 	cookie = console_srcu_read_lock();
 
 	flags = console_srcu_read_flags(con);
-	if (console_is_usable(con, flags)) {
+	if (console_is_usable(con, flags, false)) {
 		/* Bring the sequence in @ctxt up to date */
 		ctxt->seq = nbcon_seq_read(con);
 
@@ -1026,7 +1026,7 @@ static int nbcon_kthread_func(void *__console)
 
 		con_flags = console_srcu_read_flags(con);
 
-		if (console_is_usable(con, con_flags)) {
+		if (console_is_usable(con, con_flags, false)) {
 			unsigned long lock_flags;
 
 			con->device_lock(con, &lock_flags);
@@ -1322,7 +1322,7 @@ static void __nbcon_atomic_flush_pending(u64 stop_seq, bool allow_unsafe_takeove
 		if (!(flags & CON_NBCON))
 			continue;
 
-		if (!console_is_usable(con, flags))
+		if (!console_is_usable(con, flags, true))
 			continue;
 
 		if (nbcon_seq_read(con) >= stop_seq)
@@ -1639,7 +1639,7 @@ void nbcon_device_release(struct console *con)
 	 * the console is usable throughout flushing.
 	 */
 	cookie = console_srcu_read_lock();
-	if (console_is_usable(con, console_srcu_read_flags(con)) &&
+	if (console_is_usable(con, console_srcu_read_flags(con), true) &&
 	    (!con->kthread || (system_state > SYSTEM_RUNNING)) &&
 	    prb_read_valid(prb, nbcon_seq_read(con), NULL)) {
 		__nbcon_atomic_flush_pending_con(con, prb_next_reserve_seq(prb), false);
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index b58db15d2033..a2c4fe3d21cc 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -3043,7 +3043,7 @@ static bool console_flush_all(bool do_cond_resched, u64 *next_seq, bool *handove
 			if ((flags & CON_NBCON) && con->kthread)
 				continue;
 
-			if (!console_is_usable(con, flags))
+			if (!console_is_usable(con, flags, true))
 				continue;
 			any_usable = true;
 
@@ -4018,8 +4018,10 @@ static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progre
 			 * that they make forward progress, so only increment
 			 * @diff for usable consoles.
 			 */
-			if (!console_is_usable(c, flags))
+			if (!console_is_usable(c, flags, true) &&
+			    !console_is_usable(c, flags, false)) {
 				continue;
+			}
 
 			if (flags & CON_NBCON) {
 				printk_seq = nbcon_seq_read(c);
-- 
2.39.2