Re: [RFC][PATCHv5 6/7] printk: use printk_safe buffers in printk

Petr Mladek
2016-12-12T16:30:23Z

On Thu 2016-12-01 22:55:45, Sergey Senozhatsky wrote:
> Use printk_safe per-CPU buffers in printk recursion-prone blocks:
> -- around logbuf_lock protected sections in vprintk_emit() and
> console_unlock()
> -- around down_trylock_console_sem() and up_console_sem()
>
> Note that this solution addresses deadlocks caused by printk()
> recursive calls only. That is vprintk_emit() and console_unlock().
>
> Another thing to note is that we now keep lockdep enabled in printk,
> because we are protected against the printk recursion caused by lockdep
> in vprintk_emit() by the printk-safe mechanism - we first switch to
> per-CPU buffers and only then access the deadlock-prone locks.
>
> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>

Looks fine and safe to me.

Reviewed-by: Petr Mladek <pmladek@suse.com>

Best Regards,
Petr