From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ross Lagerwall <ross.lagerwall@citrix.com>
Subject: Re: [PATCH v3 07/23] xsplice: Implement support for
 applying/reverting/replacing patches. (v5)
Date: Wed, 17 Feb 2016 08:58:27 +0000
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To: Andrew Cooper <andrew.cooper3@citrix.com>
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On 02/16/2016 07:11 PM, Andrew Cooper wrote:
snip
>> +        }
>> +
>> +        barrier(); /* MUST do it after get_cpu_maps. */
>> +        total_cpus = num_online_cpus() - 1;
>> +
>> +        if ( total_cpus )
>> +        {
>> +            printk(XENLOG_DEBUG "%s: CPU%u - IPIing the %u CPUs.\n", p->name,
>> +                   cpu, total_cpus);
>> +            smp_call_function(reschedule_fn, NULL, 0);
>> +        }
>> +        (void)xsplice_do_single(total_cpus);
>> +
>> +        ASSERT(local_irq_is_enabled());
>> +
>> +        put_cpu_maps();
>> +
>> +        printk(XENLOG_DEBUG "%s finished with rc=%d\n", p->name, p->rc);
>> +    }
>> +    else
>> +    {
>> +        /* Wait for all CPUs to rendezvous. */
>> +        while ( xsplice_work.do_work && !xsplice_work.ready )
>> +        {
>> +            cpu_relax();
>> +            smp_rmb();
>> +        }
>> +
>
> What happens here if the rendezvous initiator times out?  Looks like we
> will spin forever waiting for do_work which will never drop back to 0.

xsplice_do_wait() sets do_work to 0 on a timeout.

-- 
Ross Lagerwall