Re: [RFC][PATCH v8 1/2] printk: Make printk() completely async

Jan Kara
2016-03-29T09:14:13Z

On Fri 25-03-16 00:43:22, Sergey Senozhatsky wrote:
> @@ -1655,6 +1670,14 @@ asmlinkage int vprintk_emit(int facility, int level,
> raw_spin_lock(&logbuf_lock);
> logbuf_cpu = this_cpu;
>
> + /*
> + * Set printing kthread sleep condition early, under the
> + * logbuf_lock, so it (if RUNNING) will go to console_lock()
> + * and spin on logbuf_lock.
> + */
> + if (!in_panic && printk_kthread && !need_flush_console)
> + need_flush_console = true;
> +
> if (unlikely(recursion_bug)) {
> static const char recursion_msg[] =
> "BUG: recent printk recursion!";

I like the cleaned up need_flush_console handling! Just a suggestion: It
may be more logical to handle need_flush_console setting under logbuf_lock
but after we actually store the message in the buffer, not before. Doesn't
matter for correctness now but may be more future-proof.

Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR