2024-02-18 19:00:25

by John Ogness

Subject: [PATCH printk v2 20/26] printk: Track nbcon consoles

Add a global flag @have_nbcon_console to identify if any nbcon
consoles are registered. This will be used in follow-up commits
to preserve legacy behavior when no nbcon consoles are registered.

Signed-off-by: John Ogness <[email protected]>
---
kernel/printk/printk.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 336dad179b99..2c4ab717c110 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -470,6 +470,13 @@ static DEFINE_MUTEX(syslog_lock);
*/
bool have_legacy_console;

+/*
+ * Specifies if an nbcon console is registered. If nbcon consoles are present,
+ * synchronous printing of legacy consoles will not occur during panic until
+ * the backtrace has been stored to the ringbuffer.
+ */
+static bool have_nbcon_console;
+
/*
* Specifies if a boot console is registered. If boot consoles are present,
* nbcon consoles cannot print simultaneously and must be synchronized by
@@ -3522,6 +3529,7 @@ void register_console(struct console *newcon)
console_init_seq(newcon, bootcon_registered);

if (newcon->flags & CON_NBCON) {
+ have_nbcon_console = true;
nbcon_init(newcon);
} else {
have_legacy_console = true;
@@ -3583,6 +3591,7 @@ EXPORT_SYMBOL(register_console);
static int unregister_console_locked(struct console *console)
{
bool found_legacy_con = false;
+ bool found_nbcon_con = false;
bool found_boot_con = false;
struct console *c;
int res;
@@ -3639,13 +3648,18 @@ static int unregister_console_locked(struct console *console)
for_each_console(c) {
if (c->flags & CON_BOOT)
found_boot_con = true;
- if (!(c->flags & CON_NBCON))
+
+ if (c->flags & CON_NBCON)
+ found_nbcon_con = true;
+ else
found_legacy_con = true;
}
if (!found_boot_con)
have_boot_console = false;
if (!found_legacy_con)
have_legacy_console = false;
+ if (!found_nbcon_con)
+ have_nbcon_console = false;

return res;
}
--
2.39.2

2024-03-01 09:50:24

by Petr Mladek

Subject: Re: [PATCH printk v2 20/26] printk: Track nbcon consoles

On Sun 2024-02-18 20:03:20, John Ogness wrote:
> Add a global flag @have_nbcon_console to identify if any nbcon
> consoles are registered. This will be used in follow-up commits
> to preserve legacy behavior when no nbcon consoles are registered.
>
> Signed-off-by: John Ogness <[email protected]>

Reviewed-by: Petr Mladek <[email protected]>

Best Regards,
Petr