On Sat 2016-01-23 17:15:10, Sergey Senozhatsky wrote:
> This patch moves can_use_console() check out of
> console_trylock_for_printk(). Instead it calls it in
> console_unlock(), so now console_lock()/console_unlock() are
> also 'protected' by can_use_console().
>
> Signed-off-by: Sergey Senozhatsky <[email protected]>
> ---
> kernel/printk/printk.c | 86
> ++++++++++++++++++++++++--------------------------
> 1 file changed, 42 insertions(+), 44 deletions(-)
>
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index 7ebcfea..c39232a 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -1519,21 +1492,7 @@ static inline int can_use_console(unsigned int cpu)
> */
> static int console_trylock_for_printk(void)
> {
> - unsigned int cpu = smp_processor_id();
> -
> - if (!console_trylock())
> - return 0;
> - /*
> - * If we can't use the console, we need to release the console
> - * semaphore by hand to avoid flushing the buffer. We need to hold the
> - * console semaphore in order to do this test safely.
> - */
> - if (!can_use_console(cpu)) {
> - console_locked = 0;
> - up_console_sem();
> - return 0;
> - }
> - return 1;
> + return console_trylock();
> }
I would personally remove console_trylock_for_printk() already in this
patch. I mean to fold the 3rd patch into this one.
> int printk_delay_msec __read_mostly;
> @@ -2247,9 +2233,21 @@ void console_unlock(void)
> do_cond_resched = console_may_schedule;
> console_may_schedule = 0;
>
> +again:
> + /*
> + * We released the console_sem lock, so we need to recheck if
> + * cpu is online and (if not) is there at least one CON_ANYTIME
> + * console.
> + */
> + if (!can_use_console()) {
> + console_locked = 0;
> + up_console_sem();
> + return;
> + }
This is a bug fix and a nice clean up together.
Reviewed-by: Petr Mladek <[email protected]>
Best Regards,
Petr
