Re: [PATCHv7 3/8] printk: introduce per-cpu safe_print seq buffer

[Petr Mladek]

On Tue 2016-12-27 23:16:06, Sergey Senozhatsky wrote:
> This patch extends the idea of NMI per-cpu buffers to regions
> that may cause recursive printk() calls and possible deadlocks.
> Namely, printk() can't handle printk calls from schedule code
> or printk() calls from lock debugging code (spin_dump() for instance);
> because those may be called with `sem->lock' already taken or any
> other `critical' locks (p->pi_lock, etc.). An example of deadlock
> can be
> 
> Usage example:
> 
>  printk()
>   printk_safe_enter_irqsave(flags)
>   //
>   //  any printk() call from here will endup in vprintk_safe(),
>   //  that stores messages in a special per-CPU buffer.
>   //
>   printk_safe_exit_irqrestore(flags)
> 
> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>

I really like the new variants for printk_safe_enter/exit and
different IRQ context.

Reviewed-by: Petr Mladek <pmladek@xxxxxxxx>

Best Regards,
Petr