From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@redhat.com>
Subject: Re: [PATCH 1/2] kvm: use modern cpumask primitives, no cpumask_t
 on stack
Date: Mon, 08 Dec 2008 11:49:57 +0200
Message-ID: <493CEDC5.1080004@redhat.com>
References: <200812072125.14416.rusty@rustcorp.com.au> <493BF144.9080106@redhat.com> <493BF648.6060504@redhat.com> <200812081638.07526.rusty@rustcorp.com.au>
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Cc: kvm-devel <kvm@vger.kernel.org>, linux-kernel@vger.kernel.org,
	Mike Travis <travis@sgi.com>
To: Rusty Russell <rusty@rustcorp.com.au>
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Rusty Russell wrote:
>> Btw, for the general case, instead of forcing everyone to duplicate, how 
>> about:
>>
>> cpumask_var_t cpus;
>>
>> with_cpumask(cpus) {
>>    ... code to populate cpus
>>    smp_call_function_some(...);
>> } end_with_cpumask(cpus);
>>
>> Where with_cpumask() allocates cpus, and uses a mutex + static fallback 
>> on failure.
>>     
>
> I'd prefer not to hide deadlocks that way :(
>
> I'll re-battle with that code to neaten it.  There are only a few places
> which have these kind of issues.
>
>   

cpuvar_get_maybe_mutex_lock(...);
...
cpuvar_put_maybe_mutex_unlock(...);

?

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.