[PATCH printk v5 13/40] um: kmsg_dumper: use srcu console list iterator

From: John Ogness
Date: Wed Nov 16 2022 - 11:23:08 EST


Rather than using the console_lock to guarantee safe console list
traversal, use srcu console list iteration.

Signed-off-by: John Ogness <john.ogness@xxxxxxxxxxxxx>
Reviewed-by: Petr Mladek <pmladek@xxxxxxxx>
---
arch/um/kernel/kmsg_dump.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/arch/um/kernel/kmsg_dump.c b/arch/um/kernel/kmsg_dump.c
index 40abf1e9ccb1..427dd5a61a38 100644
--- a/arch/um/kernel/kmsg_dump.c
+++ b/arch/um/kernel/kmsg_dump.c
@@ -16,29 +16,26 @@ static void kmsg_dumper_stdout(struct kmsg_dumper *dumper,
struct console *con;
unsigned long flags;
size_t len = 0;
+ int cookie;

/*
* If no consoles are available to output crash information, dump
* the kmsg buffer to stdout.
*/

- if (!console_trylock())
- return;
-
- for_each_console(con) {
+ cookie = console_srcu_read_lock();
+ for_each_console_srcu(con) {
/*
* The ttynull console and disabled consoles are ignored
* since they cannot output. All other consoles are
* expected to output the crash information.
*/
if (strcmp(con->name, "ttynull") != 0 &&
- (con->flags & CON_ENABLED)) {
+ (console_srcu_read_flags(con) & CON_ENABLED)) {
break;
}
}
-
- console_unlock();
-
+ console_srcu_read_unlock(cookie);
if (con)
return;

--
2.30.2