From: "Américo Wang" <xiyou.wangcong@gmail.com>
To: Cypher Wu <cypher.w@gmail.com>
Cc: "Américo Wang" <xiyou.wangcong@gmail.com>,
linux-kernel@vger.kernel.org,
"Chris Metcalf" <cmetcalf@tilera.com>,
"Eric Dumazet" <eric.dumazet@gmail.com>,
netdev <netdev@vger.kernel.org>
Subject: Re: Fwd: IGMP and rwlock: Dead ocurred again on TILEPro
Date: Thu, 17 Feb 2011 13:42:37 +0800 [thread overview]
Message-ID: <20110217054237.GB2653@cr0.nay.redhat.com> (raw)
In-Reply-To: <AANLkTikkro-_9pv5uJ4+SqYh9Fr480_96Wh1Pv6Pvtez@mail.gmail.com>
On Thu, Feb 17, 2011 at 01:04:14PM +0800, Cypher Wu wrote:
>>
>> Have you turned CONFIG_LOCKDEP on?
>>
>> I think Eric already converted that rwlock into RCU lock, thus
>> this problem should disappear. Could you try a new kernel?
>>
>> Thanks.
>>
>
>I haven't turned CONFIG_LOCKDEP on for test since I didn't get too
>much information when we tried to figured out the former deadlock.
>
>IGMP used read_lock() instead of read_lock_bh() since usually
>read_lock() can be called recursively, and today I've read the
>implementation of MIPS, it's should also works fine in that situation.
>The implementation of TILEPro cause problem since after it use TNS set
>the lock-val to 1 and hold the original value and before it re-set
>lock-val a new value, it a race condition window.
>
I see no reason why you can't call read_lock_bh() recursively,
read_lock_bh() is roughly equalent to local_bh_disable() + read_lock(),
both can be recursive.
But I may miss something here. :-/
next prev parent reply other threads:[~2011-02-17 5:42 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-17 3:39 Cypher Wu
2011-02-17 4:49 ` Américo Wang
2011-02-17 5:04 ` Cypher Wu
2011-02-17 5:42 ` Américo Wang [this message]
2011-02-17 5:46 ` David Miller
2011-02-17 6:39 ` Eric Dumazet
2011-02-17 22:49 ` Chris Metcalf
2011-02-17 22:53 ` David Miller
2011-02-17 23:04 ` Chris Metcalf
2011-02-17 23:11 ` David Miller
2011-02-17 23:18 ` Chris Metcalf
2011-02-18 3:16 ` Cypher Wu
2011-02-18 3:19 ` Cypher Wu
2011-02-18 7:08 ` Cypher Wu
2011-02-18 21:51 ` Chris Metcalf
2011-02-19 4:07 ` Cypher Wu
2011-02-20 13:33 ` Chris Metcalf
2011-03-01 18:30 ` [PATCH] arch/tile: fix deadlock bugs in rwlock implementation Chris Metcalf
2011-02-17 6:42 ` Fwd: IGMP and rwlock: Dead ocurred again on TILEPro Cypher Wu
-- strict thread matches above, loose matches on Subject: below --
2011-02-17 2:17 Cypher Wu
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