Re: [PATCH v2] printk: make sure to print log on console.
From: Petr Mladek
Date: Fri Jun 08 2018 - 04:39:15 EST
On Fri 2018-06-01 14:26:42, Maninder Singh wrote:
> This patch make sure printing of log on console if loglevel
> at time of storing log is less than current console loglevel.
> In SMP printk can work asynchronously, logs can be missed on console
> because it checks current log level at time of console_unlock,
> not at time of storing logs.
> console_verbose(); // user wants to have all the logs on console.
> dump_backtrace(); //prints with default loglevel.
> console_silent(); // stop all logs from printing on console.
> Now if console_lock was owned by another process, the messages might
> be handled after the consoles were silenced.
It might make sense to document the limitations reported by
Sergey. I mean to add something like:
"There are still some corner cases where this patch is not enough,
for example, when the messages are flushed later from printk_safe
buffers or when there are races between console_verbose() and
> reused flag LOG_NOCONS as its usage is gone long back.
> Signed-off-by: Vaneet Narang <v.narang@xxxxxxxxxxx>
> Signed-off-by: Maninder Singh <maninder1.s@xxxxxxxxxxx>
Anyway. the patch helps in many situations and it is a step in the right
Reviewed-by: Petr Mladek <pmladek@xxxxxxxx>
PS: There is no need to resend the patch. I could update the commit
message when pushing the patch. I am just going to wait a bit for
other potential reviewers.