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From: Tom Zanussi <>
To: Oleg Nesterov <>
Cc: Andrew Morton <>,
	Karim Yaghmour <>,
Subject: Re: kernel/relay.c: a strange usage of delayed_work
Date: Fri, 04 May 2007 00:42:30 -0500	[thread overview]
Message-ID: <1178257351.4623.16.camel@ubuntu> (raw)
In-Reply-To: <>

On Fri, 2007-05-04 at 01:38 +0400, Oleg Nesterov wrote:
> relay_switch_subbuf() does schedule_delayed_work(&buf->wake_readers, 1),
> wakeup_readers() only does wake_up_interruptible() and nothing more.
> Why can't we use a plain timer for this?
> In any case, this "wake_up ->read_wait after a minimal possible delay"
> looks somewhat strange to me, could you explain? just curious.

The reason it's done that way is that if the event that causes the
relay_switch_subbuf() happens to be an event logged from schedule(), and
we directly call wake_up_interruptible() at that point, we lock up the
machine because it ends up back in schedule().  Deferring it avoids the

I don't see any problem with using a plain timer instead - I'll work up
a patch to make that change.


  reply	other threads:[~2007-05-04  5:47 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-04-25 23:10 2.6.21-rc7-mm1: BUG_ON in kthread_bind during _cpu_down Rafael J. Wysocki
2007-04-25 23:54 ` Andrew Morton
2007-04-26 10:09   ` Gautham R Shenoy
2007-04-26 10:15     ` Oleg Nesterov
2007-04-26 12:58       ` Gautham R Shenoy
2007-04-28  1:42         ` Andrew Morton
2007-05-01 18:48           ` [PATCH] add-suspend-related-notifications-for-cpu-hotplug-cleanup Oleg Nesterov
2007-05-01 22:56           ` libata-core.c: unsafe cancel_delayed_work() usage? Oleg Nesterov
2007-05-01 23:35             ` Jeff Garzik
2007-05-01 23:48               ` Oleg Nesterov
2007-05-03 21:38           ` kernel/relay.c: a strange usage of delayed_work Oleg Nesterov
2007-05-04  5:42             ` Tom Zanussi [this message]
2007-04-26 10:20     ` 2.6.21-rc7-mm1: BUG_ON in kthread_bind during _cpu_down Eric W. Biederman
2007-04-26 20:20   ` Rafael J. Wysocki

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