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authorJohn Ogness <john.ogness@linutronix.de>2023-07-17 22:46:01 +0300
committerPetr Mladek <pmladek@suse.com>2023-07-20 14:06:22 +0300
commit6d3e0d8cc63221dec670d0ee92ac57961581e975 (patch)
tree73b926b088fb8df780fb73a7828c6c984bb76bcc
parent7ec85f3e089aa423a69559bf4555b6218b5a2ef7 (diff)
downloadlinux-6d3e0d8cc63221dec670d0ee92ac57961581e975.tar.xz
kdb: Do not assume write() callback available
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
-rw-r--r--kernel/debug/kdb/kdb_io.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
index 5c7e9ba7cd6b..e9139dfc1f0a 100644
--- 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 *msg, int msg_len)
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