linux-kernel - Re: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver lowest-priority interrupts

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Message-ID: <20160122140154.GD14104@potion.brq.redhat.com>
Date:	Fri, 22 Jan 2016 15:01:54 +0100
From:	Radim Krcmár <rkrcmar@...hat.com>
To:	"Wu, Feng" <feng.wu@...el.com>
Cc:	"pbonzini@...hat.com" <pbonzini@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>
Subject: Re: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver
 lowest-priority interrupts

2016-01-22 05:12+0000, Wu, Feng:
>> From: Radim Krčmář [mailto:rkrcmar@...hat.com]
>> 2016-01-20 09:42+0800, Feng Wu:
>> > +{
>> > +	u32 mod;
>> > +	int i, idx = 0;
>> > +
>> > +	mod = vector % dest_vcpus;
>> > +
>> > +	for (i = 0; i <= mod; i++) {
>> > +		idx = find_next_bit(bitmap, bitmap_size, idx) + 1;
>> 
>> I'd remove this "+ 1".  Current users don't check for errors and always
>> do "- 1".  The new error value could be 'idx = bitmap_size', with u32 as
>> return type.
>> 
> 
> Does the following code look good to you:
> 
>         u32 mod;
>         int i, idx = -1;
> 
>         mod = vector % dest_vcpus;
> 
>         for (i = 0; i <= mod; i++) {
>                 idx = find_next_bit(bitmap, bitmap_size, idx + 1);
>                 BUG_ON(idx == bitmap_size);
>         }
> 
>         return idx;

It's ok, thanks.