From: Petr Mladek <pmladek@suse.com>
To: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
"David S. Miller" <davem@davemloft.net>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
Kay Sievers <kay@vrfy.org>, Josh Triplett <josh@joshtriplett.org>,
Linux Embedded <linux-embedded@vger.kernel.org>,
Geert Uytterhoeven <geert@linux-m68k.org>
Subject: Re: [PATCH v4.2-rc1] printk: make extended printk support conditional on netconsole
Date: Wed, 1 Jul 2015 18:05:13 +0200 [thread overview]
Message-ID: <20150701160513.GC8099@pathway.suse.cz> (raw)
In-Reply-To: <20150629233140.GA7711@mtj.duckdns.org>
On Mon 2015-06-29 19:31:40, Tejun Heo wrote:
> 6fe29354befe ("printk: implement support for extended console
> drivers") implemented extended printk support for extended netconsole.
> The code added was miniscule but it added static 8k buffer
> unconditionally unnecessarily bloating the kernel for cases where
> extended netconsole is not used.
>
> This patch introduces CONFIG_PRINTK_CON_EXTENDED which is selected by
> CONFIG_NETCONSOLE. If the config option is not set, extended printk
> support is compiled out along with the static buffer.
>
> Verified 8k reduction in vmlinux bss when !CONFIG_NETCONSOLE.
>
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Reported-and-suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
> ---
> Linus, Andrew.
>
> This removes an unnecessary 8k bss bloat introduced during v4.2-rc1
> merge window on certain configs. The original patch was routed
> through -mm. How should this be routed?
>
> Thanks.
>
> drivers/net/Kconfig | 1 +
> init/Kconfig | 3 +++
> kernel/printk/printk.c | 33 +++++++++++++++++++++++++++++----
> 3 files changed, 33 insertions(+), 4 deletions(-)
[...]
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
[...]
> @@ -2561,9 +2584,11 @@ void register_console(struct console *ne
> console_drivers->next = newcon;
> }
>
> - if (newcon->flags & CON_EXTENDED)
> - if (!nr_ext_console_drivers++)
> + if (newcon->flags & CON_EXTENDED) {
> + if (!nr_ext_console_drivers)
> pr_info("printk: continuation disabled due to ext consoles, expect more fragments in /dev/kmsg\n");
> + inc_nr_ext_console_drivers();
We should handle also the situation when CON_EXTENDED is set
and CONFIG_PRINTK_CON_EXTENDED is not set by mistake. Otherwise,
we will not increment nr_ext_console_drivers here => ext_text will
not be filled in console_unlock() => call_console_drivers()
will print nothing for the CON_EXTENDED console.
At least, I would print an error here. Something like.
#ifndef CONFIG_PRINTK_CON_EXTENDED
pr_err("The registered extended console will print nothing because the kernel is not compiled with PRINTK_CON_EXTENDED\n");
#endif
I wonder if there is a good identification of the console that can be printed.
Otherwise, it looks fine to me.
Best Regards,
Petr
next prev parent reply other threads:[~2015-07-01 16:05 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-29 14:45 [PATCHSET] printk: implement extended console support Tejun Heo
2015-04-29 14:45 ` [PATCH 1/3] printk: guard the amount written per line by devkmsg_read() Tejun Heo
2015-04-29 14:45 ` [PATCH 2/3] printk: factor out message formatting from devkmsg_read() Tejun Heo
2015-04-29 14:45 ` [PATCH 3/3] printk: implement support for extended console drivers Tejun Heo
2015-04-30 21:31 ` Andrew Morton
2015-04-30 22:12 ` Tejun Heo
2015-04-30 22:15 ` Andrew Morton
2015-05-01 16:23 ` [PATCH v3 " Tejun Heo
2015-06-29 9:20 ` [PATCH " Geert Uytterhoeven
2015-06-29 15:28 ` Tejun Heo
2015-06-29 15:47 ` Geert Uytterhoeven
2015-06-29 15:49 ` Tejun Heo
2015-06-29 16:11 ` josh
2015-06-29 16:11 ` Geert Uytterhoeven
2015-06-29 16:13 ` Tejun Heo
2015-06-29 16:50 ` josh
2015-06-29 23:31 ` [PATCH v4.2-rc1] printk: make extended printk support conditional on netconsole Tejun Heo
2015-07-01 16:05 ` Petr Mladek [this message]
2015-07-02 16:21 ` [PATCH v2 " Tejun Heo
2015-07-03 14:07 ` Petr Mladek
2015-07-03 15:25 ` Tejun Heo
2015-07-03 16:22 ` [PATCH v3 " Tejun Heo
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