[PATCH printk v2 22/38] serial: kgdboc: document console_lock usage
From: John Ogness <john.ogness@linutronix.de>
Date: 2022-10-19 15:06:06
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Subsystem:
kgdb / kdb /debug_core, the rest, tty layer and serial drivers · Maintainers:
Jason Wessel, Daniel Thompson, Linus Torvalds, Greg Kroah-Hartman, Jiri Slaby
kgdboc_earlycon_init() uses the console_lock to ensure that no consoles are unregistered until the kgdboc_earlycon is setup. This is necessary because the trapping of the exit() callback assumes that the exit() callback is not called before the trap is setup. Explicitly document this non-typical console_lock usage. Signed-off-by: John Ogness <john.ogness@linutronix.de> --- drivers/tty/serial/kgdboc.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c
index e9d3f8c6e3dc..48000666789a 100644
--- a/drivers/tty/serial/kgdboc.c
+++ b/drivers/tty/serial/kgdboc.c@@ -545,6 +545,14 @@ static int __init kgdboc_earlycon_init(char *opt) * Look for a matching console, or if the name was left blank just * pick the first one we find. */ + + /* + * Hold the console_lock to guarantee that no consoles are + * unregistered until the kgdboc_earlycon setup is complete. + * Trapping the exit() callback relies on exit() not being + * called until the trap is setup. This also allows safe + * traversal of the console list. + */ console_lock(); for_each_console(con) { if (con->write && con->read &&
--
2.30.2