| From 6d3e0d8cc63221dec670d0ee92ac57961581e975 Mon Sep 17 00:00:00 2001 |
| From: John Ogness <john.ogness@linutronix.de> |
| Date: Mon, 17 Jul 2023 21:52:01 +0206 |
| Subject: kdb: Do not assume write() callback available |
| |
| From: John Ogness <john.ogness@linutronix.de> |
| |
| commit 6d3e0d8cc63221dec670d0ee92ac57961581e975 upstream. |
| |
| It is allowed for consoles to not provide a write() callback. For |
| example ttynull does this. |
| |
| Check if a write() callback is available before using it. |
| |
| Signed-off-by: John Ogness <john.ogness@linutronix.de> |
| Reviewed-by: Petr Mladek <pmladek@suse.com> |
| Reviewed-by: Douglas Anderson <dianders@chromium.org> |
| Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> |
| Acked-by: Daniel Thompson <daniel.thompson@linaro.org> |
| Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org> |
| Signed-off-by: Petr Mladek <pmladek@suse.com> |
| Link: https://lore.kernel.org/r/20230717194607.145135-2-john.ogness@linutronix.de |
| Cc: Brian Norris <briannorris@chromium.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| kernel/debug/kdb/kdb_io.c | 2 ++ |
| 1 file changed, 2 insertions(+) |
| |
| --- a/kernel/debug/kdb/kdb_io.c |
| +++ b/kernel/debug/kdb/kdb_io.c |
| @@ -576,6 +576,8 @@ static void kdb_msg_write(const char *ms |
| continue; |
| if (c == dbg_io_ops->cons) |
| continue; |
| + if (!c->write) |
| + continue; |
| /* |
| * Set oops_in_progress to encourage the console drivers to |
| * disregard their internal spin locks: in the current calling |
