| From | John Ogness <> | Subject | [PATCH printk v3 15/40] kdb: use srcu console list iterator | Date | Mon, 7 Nov 2022 15:22:13 +0106 |
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Guarantee safe iteration of the console list by using SRCU.
Signed-off-by: John Ogness <john.ogness@linutronix.de> --- kernel/debug/kdb/kdb_io.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c index 550fe8b456ec..ed8289ce4fcb 100644 --- a/kernel/debug/kdb/kdb_io.c +++ b/kernel/debug/kdb/kdb_io.c @@ -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) @@ -558,7 +559,15 @@ static void kdb_msg_write(const char *msg, int msg_len) cp++; } - for_each_console(c) { + /* + * 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. (Note that there + * is no guarantee for either criteria.) + */ + cookie = console_srcu_read_lock(); + for_each_console_srcu(c) { if (!console_is_enabled(c)) continue; if (c == dbg_io_ops->cons) @@ -577,6 +586,7 @@ 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) -- 2.30.2
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