From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <ddde182808bdb363b6ed3c1501cbea21@rei2.9hal>
Date: Thu, 23 Aug 2012 11:47:14 +0200
From: cinap_lenrek@gmx.de
To: 9fans@9fans.net
In-Reply-To: <2558025d29ad87b629bc88c6e6a043a3@kw.quanstro.net>
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Subject: Re: [9fans] devmnt crash, fix.
Topicbox-Message-UUID: ae3e7388-ead7-11e9-9d60-3106f5b1d025

can you provide the source file, dont have current 9atom iso handy
and the stuff i found on the net doesnt seem to cut it. however,
i found http://www.quanstro.net/plan9/sleepwake.html which at the
end gives a solution to the problem:

void
dowake(Io *i)
{
	i->cond = 1;
	wakeup(i);
	i->cond = 2;		/* atomic */
	/* hands off i now */
}
void
doio(void)
{
	Io *i;

	dispatch(i = malloc(sizeof *i));
	while(waserror())
		/* eat note */;
	sleep(i, iodone, i);
	poperror();
	while(i->cond != 2)
		/* rendez not done */;
	free(i);
}

that would be relatively easy to apply to devmnt and doesnt have the
problem of spurious wakeups with abusing up->sleep as rendez.

--
cinap