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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Joe Perches <joe@perches.com>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Petr Mladek <pmladek@suse.cz>,
	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Subject: Re: linux.git: printk() problem
Date: Mon, 24 Oct 2016 10:54:30 -0700	[thread overview]
Message-ID: <CA+55aFwNU_ggMjguqFNHpY6r4UmsLuu3-rXKoNRi8umRNCRJQw@mail.gmail.com> (raw)
In-Reply-To: <20161024140845.GA626@swordfish>

On Mon, Oct 24, 2016 at 7:08 AM, Sergey Senozhatsky
<sergey.senozhatsky@gmail.com> wrote:
>
> is mod_timer() safe enough to rely on/call from
>         panic()->console_flush_on_panic()->console_unlock() ?

I don't think that's a big issue: the whole "panic()" siotuation is
very much about best effort.

> shouldn't deferred_cont_flush() be called every time we jump
> to `again' label in console_unlock()?

actually, I think we should just do it at the end.

And your "spinlock bad magic" reports says to me that we should
actually delay it even more, and just do it in klogd, to avoid the
whole issue with "printk() is used very _very_ early during boot".

Because if klogd isn't even running yet, then we clearly don't care
about timely flushing to the logs.

So here's a new version - TOTALLY UNTESTED! - that removes even more
redundant code (all the "test previous record flags" crud - it is not
sensible to think that the previous record was what a continuation was
all about, since the whole reason the continuation didn't get merged
was that something else happened in between).

Note the "totally untested" part. It compiles for me. But it may do
unspeakably stupid things. Caveat applior.

             Linus

  parent reply	other threads:[~2016-10-24 17:54 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-10-12 13:30 linux.git: printk() problem Tetsuo Handa
2016-10-12 14:35 ` Michal Hocko
2016-10-12 16:08   ` Joe Perches
2016-10-13  6:26     ` Michal Hocko
2016-10-13  9:29       ` Joe Perches
2016-10-13 10:04         ` Michal Hocko
2016-10-13 10:20           ` Joe Perches
2016-10-13 11:06             ` Michal Hocko
2016-10-12 15:47 ` Linus Torvalds
2016-10-12 16:16   ` Joe Perches
2016-10-12 16:54     ` Linus Torvalds
2016-10-12 18:50       ` [PATCH] acpi_os_vprintf: Use printk_get_level() to avoid unnecessary KERN_CONT Joe Perches
2016-10-13 21:59         ` Rafael J. Wysocki
2016-10-23  9:22   ` linux.git: printk() problem Geert Uytterhoeven
2016-10-23 18:11     ` Linus Torvalds
2016-10-23 19:06       ` Joe Perches
2016-10-23 19:32         ` Linus Torvalds
2016-10-23 19:46           ` Linus Torvalds
2016-10-24 11:15             ` Geert Uytterhoeven
2016-10-24 14:08             ` Sergey Senozhatsky
2016-10-24 14:23               ` Sergey Senozhatsky
2016-10-24 17:54               ` Linus Torvalds [this message]
2016-10-24 17:55                 ` Linus Torvalds
2016-10-25  1:55                   ` Sergey Senozhatsky
2016-10-25  2:06                     ` Linus Torvalds
2016-10-25  2:22                       ` Linus Torvalds
2016-10-25  4:06                         ` Sergey Senozhatsky
2016-10-25  4:13                           ` Joe Perches
2016-10-25  4:15                           ` Linus Torvalds
2016-10-25  4:44                             ` Sergey Senozhatsky
2016-10-25 14:44                         ` Petr Mladek
2016-11-09 15:47                         ` Petr Mladek
2016-10-25  2:24                     ` Sergey Senozhatsky
2016-10-23 20:33           ` Joe Perches
2016-10-23 21:13             ` Linus Torvalds
2016-10-25 14:42       ` Steven Rostedt

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