From: "Bu, Yitian" <ybu@qti.qualcomm.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "tglx@linutronix.de" <tglx@linutronix.de>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"mingo@kernel.org" <mingo@kernel.org>
Subject: RE: [PATCH] Fix rq->lock vs logbuf_lock unlock race
Date: Wed, 20 Feb 2013 11:24:36 +0000 [thread overview]
Message-ID: <E807E903FE6CBE4D95E420FBFCC273B827526E@nasanexd01h.na.qualcomm.com> (raw)
In-Reply-To: <1361355555.10155.14.camel@laptop>
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="utf-8", Size: 1352 bytes --]
> Unfortunately that's not quite possible, rq->lock is really out of bounds. At
> one point I tried 'fixing' this but there's a whole bunch of nasty that's not
> going to go away.
>
> I've since forgotten most of the details, but aside from logbuf problems
> there's a whole host of issues with the console drivers themselves as well.
>
> If you really want to do this, use early_printk.
Hi Peter:
The patch 0b5e1c5255e("printk: Release console_sem after logbuf_lock" )
is as below:
console_locked = 0;
- up(&console_sem);
+ wake = 1;
retval = 0;
}
}
printk_cpu = UINT_MAX;
spin_unlock(&logbuf_lock);
+ if (wake)
+ up(&console_sem);
return retval;
the patch 07354eb1a74d1("locking, printk: Annotate logbuf_lock as raw ")
is as below:
printk_cpu = UINT_MAX;
- spin_unlock(&logbuf_lock);
if (wake)
up(&console_sem);
+ raw_spin_unlock(&logbuf_lock);
return retval;
}
Note that the purpose of patch 07354eb1a74d1 is to use raw_spin_unlock
instead of spin_unlock, it is not supposed to change any lock sequences.
What I do is to revert this change to 0b5e1c5255e, and it is nothing to do with
how people use printk. It is just to recover a merge mistake.
ÿôèº{.nÇ+‰·Ÿ®‰†+%ŠËÿ±éݶ\x17¥Šwÿº{.nÇ+‰·¥Š{±þG«éÿŠ{ayº\x1dʇڙë,j\a¢f£¢·hšïêÿ‘êçz_è®\x03(階ŠÝ¢j"ú\x1a¶^[m§ÿÿ¾\a«þG«éÿ¢¸?™¨èÚ&£ø§~á¶iO•æ¬z·švØ^\x14\x04\x1a¶^[m§ÿÿÃ\fÿ¶ìÿ¢¸?–I¥
prev parent reply other threads:[~2013-02-20 11:24 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-18 12:53 [PATCH] Fix rq->lock vs logbuf_lock unlock race Bu, Yitian
2013-02-18 14:17 ` [tip:core/printk] printk: Fix rq-> lock vs logbuf_lock unlock lock inversion tip-bot for Bu, Yitian
2013-02-20 8:45 ` [PATCH] Fix rq->lock vs logbuf_lock unlock race Peter Zijlstra
2013-02-20 9:38 ` Bu, Yitian
2013-02-20 10:19 ` Peter Zijlstra
2013-02-20 11:24 ` Bu, Yitian [this message]
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=E807E903FE6CBE4D95E420FBFCC273B827526E@nasanexd01h.na.qualcomm.com \
--to=ybu@qti.qualcomm.com \
--cc=a.p.zijlstra@chello.nl \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=tglx@linutronix.de \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).