linux-kernel - Re: [PATCH] kvm: avoid unused variable warning for UP builds

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <b6b2bd61-6178-680c-9a81-8ff1a7efe7f4@redhat.com>
Date:   Wed, 5 Jul 2017 14:26:56 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Paolo Bonzini <pbonzini@...hat.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     paulus@...abs.org, stable@...r.kernel.org
Subject: Re: [PATCH] kvm: avoid unused variable warning for UP builds

On 05.07.2017 14:24, Paolo Bonzini wrote:
> 
> 
> On 05/07/2017 14:22, David Hildenbrand wrote:
>>> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
>>> index f0fe9d02f6bb..09368501d9cf 100644
>>> --- a/virt/kvm/kvm_main.c
>>> +++ b/virt/kvm/kvm_main.c
>>> @@ -187,12 +187,23 @@ static void ack_flush(void *_completed)
>>>  {
>>>  }
>>>  
>>> +static inline bool kvm_kick_many_cpus(const struct cpumask *cpus, bool wait)
>>> +{
>>> +	if (unlikely(!cpus))
>>> +		cpus = cpu_online_mask;
>>> +
>>> +	if (cpumask_empty(cpus))
>>> +		return false;
>>> +
>>> +	smp_call_function_many(cpus, ack_flush, NULL, wait);
>>> +	return true;
>>> +}
>>
>> wonder if the !cpus case would be worth moving into smp_call_function_many.
>>
>> smp_call_function_many() might also not kick any cpu, so we could make
>> it return if it actually kicked/called this on any cpu. Then you could
>> even get rid of the special handling of cpumask_empty(cpus) here and
>> simply return the result of smp_call_function_many.
> 
> Separate patch of course. :)

Sure, for now take my

Reviewed-by: David Hildenbrand <david@...hat.com>

:)

>>
>> Is the !! really needed here? I think not.
> 
> I prefer having it.  There are corner cases (e.g. isolating bit 32 or
> higher and the function accepting an unsigned int instead of a bool)
> where it can save your butt, and it's idiomatic C.

Ah, I remember again why using booleans was once considered bad :)

Makes sense.

> 
> Paolo


-- 

Thanks,

David