From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Byungchul Park <byungchul.park@lge.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Jan Kara <jack@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
Jan Kara <jack@suse.com>, Petr Mladek <pmladek@suse.com>,
Tejun Heo <tj@kernel.org>,
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH v4 1/2] printk: Make printk() completely async
Date: Wed, 16 Mar 2016 16:56:05 +0900 [thread overview]
Message-ID: <20160316075605.GE3217@swordfish> (raw)
In-Reply-To: <20160316073007.GL5220@X58A-UD3R>
On (03/16/16 16:30), Byungchul Park wrote:
>
> Do you mean the wake_up_process() in console_unlock?
no, I meant wake_up_process(printk_kthread), the newly added one.
-- if we are going to have wake_up_process() in wake_up_klogd_work_func(),
then we need `in_sched' message to potentially trigger a recursion chain
wake_up_klogd_work_func()->wake_up_process()->printk()->wake_up_process()->printk()...
to break this printk()->wake_up_process()->printk(), we need wake_up_process() to
be under the logbuf lock; so vprintk_emit()'s if (logbuf_cpu == this_cpu) will act.
-- if we are going to have wake_up_process() in console_unlock(), then
console_unlock()->{up(), wake_up_process()}->printk()->{console_lock(), console_unlock()}->{up(), wake_up_process()}->printk()...
is undetectable... by the time console_unlock() calls wake_up_process() there
are no printk() locks that this CPU owns.
> I said they should be kept *out of* the critical section. :-)
> Otherwise, it can recurse us forever.
can you explain?
-ss
next prev parent reply other threads:[~2016-03-16 7:56 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-14 14:13 [RFC][PATCH v4 0/2] printk: Make printk() completely async Sergey Senozhatsky
2016-03-14 14:13 ` [RFC][PATCH v4 1/2] " Sergey Senozhatsky
2016-03-15 10:03 ` Jan Kara
2016-03-15 14:07 ` Sergey Senozhatsky
2016-03-16 5:39 ` Byungchul Park
2016-03-16 6:58 ` Sergey Senozhatsky
2016-03-16 7:30 ` Byungchul Park
2016-03-16 7:56 ` Sergey Senozhatsky [this message]
2016-03-16 10:34 ` Byungchul Park
2016-03-17 0:34 ` Sergey Senozhatsky
2016-03-18 5:49 ` Byungchul Park
2016-03-18 7:11 ` Sergey Senozhatsky
2016-03-18 8:23 ` byungchul.park
2016-03-16 7:00 ` Byungchul Park
2016-03-16 7:07 ` Sergey Senozhatsky
2016-03-15 15:58 ` Petr Mladek
2016-03-16 2:01 ` Sergey Senozhatsky
2016-03-16 2:10 ` Byungchul Park
2016-03-16 2:31 ` Sergey Senozhatsky
2016-03-14 14:13 ` [RFC][PATCH v4 2/2] printk: Skip messages on oops Sergey Senozhatsky
2016-03-17 10:56 ` Sergey Senozhatsky
2016-04-23 19:36 ` [RFC][PATCH v4 0/2] printk: Make printk() completely async Pavel Machek
2016-04-24 5:03 ` Sergey Senozhatsky
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160316075605.GE3217@swordfish \
--to=sergey.senozhatsky.work@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=byungchul.park@lge.com \
--cc=jack@suse.com \
--cc=jack@suse.cz \
--cc=linux-kernel@vger.kernel.org \
--cc=penguin-kernel@I-love.SAKURA.ne.jp \
--cc=pmladek@suse.com \
--cc=sergey.senozhatsky@gmail.com \
--cc=tj@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.