From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Thu, 08 May 2008 22:26:55 +0200
From: Jan Kiszka <jan.kiszka@domain.hid>
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Subject: [Adeos-main] [BUG] ipipe_sync_stage deadlock
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I love KVM - not only because I'm heavily hacking on it now, also
because it is so easy to trigger various kinds of guest issues with
it (SMP host + threaded virtual CPUs =3D> true SMP guest - and if you
want to watch fancy things happen, just load one host core).

Here is one I found that way:

void fastcall __ipipe_sync_stage(unsigned long syncmask)
{
[ ... ]
	while ((mask =3D (ipipe_this_cpudom_var(irqpend_himask) & syncmask)) !=3D=
 0) {
		level =3D __ipipe_ffnz(mask);

		while ((submask =3D ipipe_this_cpudom_var(irqpend_lomask)[level]) !=3D =
0) {
			rank =3D __ipipe_ffnz(submask);
			irq =3D (level << IPIPE_IRQ_ISHIFT) + rank;

			if (test_bit(IPIPE_LOCK_FLAG, &ipd->irqs[irq].control)) {
				__clear_bit(rank, &ipipe_this_cpudom_var(irqpend_lomask)[level]);
				continue;
			}

			__clear_bit(rank, &ipipe_this_cpudom_var(irqpend_lomask)[level]);

			if (ipipe_this_cpudom_var(irqpend_lomask)[level] =3D=3D 0)
				__clear_bit(level, &ipipe_this_cpudom_var(irqpend_himask));
[ ... ]

Who sees the deadlock? 100 points for the right answer! But be quick,
I'm already hacking on a fix. :)

Jan


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