From mboxrd@z Thu Jan  1 00:00:00 1970
From: malahal@us.ibm.com
Subject: Re: [PATCH 0/2] Add suspended state check for target
	messages
Date: Fri, 13 Nov 2009 10:30:47 -0800
Message-ID: <20091113183047.GA19866@us.ibm.com>
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	<4AFD3358.7000007@ct.jp.nec.com>
	<20091113141930.GA3185@agk-dp.fab.redhat.com>
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Alasdair G Kergon [agk@redhat.com] wrote:
> Would DMF_BLOCK_IO_FOR_SUSPEND work instead?

Should, provided that multipath_message() and multipath_postsuspend()
use some lock to synchronize. Without the lock, multipath_postsuspend()
could be executed between multipath_message's bit flag check and
its action().

multipath_message()
{
	lock();
	if (DMF_BLOCK_IO_FOR_SUSPEND is set) {
		unlock and fail;
	} else { /* postsuspend has not been executed yet and won't be
	completed until we are done here */
		action();
	}
	unlock();
}

multipath_postsuspend()
{
	lock();
	flush work();
	unlock();
}