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kdb: use srcu console list iterator

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Guarantee safe iteration of the console list by using SRCU.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Aaron Tomlin <atomlin@atomlin.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-15-john.ogness@linutronix.de
This commit is contained in:
John Ogness 2022-11-16 17:27:26 +01:06 committed by Petr Mladek
parent 12335446e0
commit b8ef04be6e
1 changed files with 16 additions and 2 deletions
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18
kernel/debug/kdb/kdb_io.c
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@ -545,6 +545,7 @@ static void kdb_msg_write(const char *msg, int msg_len)
{ {
struct console *c; struct console *c;
const char *cp; const char *cp;
int cookie;
int len; int len;
if (msg_len == 0) if (msg_len == 0)
@ -558,8 +559,20 @@ static void kdb_msg_write(const char *msg, int msg_len)
cp++; 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; continue;
if (c == dbg_io_ops->cons) if (c == dbg_io_ops->cons)
continue; continue;
@ -577,6 +590,7 @@ static void kdb_msg_write(const char *msg, int msg_len)
--oops_in_progress; --oops_in_progress;
touch_nmi_watchdog(); touch_nmi_watchdog();
} }
console_srcu_read_unlock(cookie);
} }
int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap) int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap)