Commit b8ef04be authored by John Ogness's avatar John Ogness Committed by Petr Mladek
Browse files

kdb: use srcu console list iterator 



Guarantee safe iteration of the console list by using SRCU.

Signed-off-by: default avatarJohn Ogness <john.ogness@linutronix.de>
Reviewed-by: default avatarPetr Mladek <pmladek@suse.com>
Reviewed-by: default avatarAaron Tomlin <atomlin@atomlin.com>
Reviewed-by: default avatarDouglas Anderson <dianders@chromium.org>
Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-15-john.ogness@linutronix.de
parent 12335446

kernel/debug/kdb/kdb_io.c

+16 −2
Original line number Diff line number Diff line
@@ -545,6 +545,7 @@ static void kdb_msg_write(const char *msg, int msg_len) 
{

	struct console *c;

	const char *cp;

	int cookie;

	int len;



	if (msg_len == 0)
@@ -558,8 +559,20 @@ static void kdb_msg_write(const char *msg, int msg_len) 
		cp++;

	}



	for_each_console(c) {

		if (!(c->flags & CON_ENABLED))

	/*

	 * The console_srcu_read_lock() only provides safe console list

	 * traversal. The use of the ->write() callback relies on all other

	 * CPUs being stopped at the moment and console drivers being able to

	 * handle reentrance when @oops_in_progress is set.

	 *

	 * There is no guarantee that every console driver can handle

	 * reentrance in this way; the developer deploying the debugger

	 * is responsible for ensuring that the console drivers they

	 * have selected handle reentrance appropriately.

	 */

	cookie = console_srcu_read_lock();

	for_each_console_srcu(c) {

		if (!(console_srcu_read_flags(c) & CON_ENABLED))

			continue;

		if (c == dbg_io_ops->cons)

			continue;
@@ -577,6 +590,7 @@ static void kdb_msg_write(const char *msg, int msg_len) 
		--oops_in_progress;

		touch_nmi_watchdog();

	}

	console_srcu_read_unlock(cookie);

}



int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap)