From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Thu, 08 May 2008 23:00:46 +0200
From: Philippe Gerum <rpm@xenomai.org>
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Sender: Philippe Gerum <philippe.gerum@domain.hid>
Subject: Re: [Adeos-main] [BUG] ipipe_sync_stage deadlock
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To: Jan Kiszka <jan.kiszka@domain.hid>
Cc: adeos-main <adeos-main@gna.org>

Philippe Gerum wrote:
> Jan Kiszka wrote:
>> 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 => 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 = (ipipe_this_cpudom_var(irqpend_himask) & syncmask)) != 0) {
>> 		level = __ipipe_ffnz(mask);
>>
>> 		while ((submask = ipipe_this_cpudom_var(irqpend_lomask)[level]) != 0) {
>> 			rank = __ipipe_ffnz(submask);
>> 			irq = (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;
> +				goto rpm_needs_more_neurons;
>> 			}
>>
>> 			__clear_bit(rank, &ipipe_this_cpudom_var(irqpend_lomask)[level]);
>>
> + rpm_needs_more_neurons:
>> 			if (ipipe_this_cpudom_var(irqpend_lomask)[level] == 0)
>> 				__clear_bit(level, &ipipe_this_cpudom_var(irqpend_himask));
>> [ ... ]
>>

Of course, I'm not saying this is the real fix, but that just points at a
possible issue. I do want those 100 points on my score card.

>> 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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>> Adeos-main mailing list
>> Adeos-main@domain.hid
>> https://mail.gna.org/listinfo/adeos-main
> 
> 


-- 
Philippe.