[tip: sched/rt] printk: Let console_is_usable() handle nbcon

[tip-bot2 for John Ogness]

The following commit has been merged into the sched/rt branch of tip:

Commit-ID:     20846d1ce2adacd2b1f8672e24d6acb26b2e757b
Gitweb:        https://git.kernel.org/tip/20846d1ce2adacd2b1f8672e24d6acb26b2e757b
Author:        John Ogness <john.ogness@xxxxxxxxxxxxx>
AuthorDate:    Tue, 20 Aug 2024 08:35:43 +02:06
Committer:     Petr Mladek <pmladek@xxxxxxxx>
CommitterDate: Wed, 21 Aug 2024 14:56:24 +02:00

printk: Let console_is_usable() handle nbcon

The nbcon consoles use a different printing callback. For nbcon
consoles, check for the write_atomic() callback instead of
write().

Signed-off-by: John Ogness <john.ogness@xxxxxxxxxxxxx>
Reviewed-by: Petr Mladek <pmladek@xxxxxxxx>
Link: https://lore.kernel.org/r/20240820063001.36405-18-john.ogness@xxxxxxxxxxxxx
Signed-off-by: Petr Mladek <pmladek@xxxxxxxx>
---
 kernel/printk/internal.h | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
index 5d9deb5..448a5fc 100644
--- a/kernel/printk/internal.h
+++ b/kernel/printk/internal.h
@@ -86,6 +86,8 @@ void nbcon_free(struct console *con);
 
 /*
  * 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.
  *
  * Requires the console_srcu_read_lock.
@@ -100,8 +102,13 @@ static inline bool console_is_usable(struct console *con)
 	if ((flags & CON_SUSPENDED))
 		return false;
 
-	if (!con->write)
-		return false;
+	if (flags & CON_NBCON) {
+		if (!con->write_atomic)
+			return false;
+	} else {
+		if (!con->write)
+			return false;
+	}
 
 	/*
 	 * Console drivers may assume that per-cpu resources have been