linux-kernel - [PATCH 0/2] printk: always report dropped messages

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Date:   Sat, 24 Dec 2016 23:09:00 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Peter Hurley <peter@...leysoftware.com>,
        linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Subject: [PATCH 0/2] printk: always report dropped messages

Hello,

	Two patches: trivial clean up and console_unlock() "fix".

The `printk messages dropped' report is printed as part of actual
kernel message, that's why we do 'text + len, sizeof(text) - len'
later in msg_print_text().

The problem here is that we may eventually skip the message, and
thus lose the 'printk messages dropped' report, if `console_loglevel'
check tells us to do so. Missing kernel messages in serial log
together with the missing 'printk messages dropped' can be quite
confusing.

There are two options to address it:
a) forbid suppress_message_printing() if we know that we must print
   `printk messages dropped'

b) print `printk messages dropped' as a standalone message.

Sergey Senozhatsky (2):
  printk: drop call_console_drivers() unused param
  printk: always report lost messages on serial console

 kernel/printk/printk.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

-- 
2.11.0