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Date: Wed, 17 Mar 2010 23:48:52 -0300 From: Marcelo Tosatti <mtosatti@...hat.com> To: Xiao Guangrong <xiaoguangrong@...fujitsu.com> Cc: Avi Kivity <avi@...hat.com>, Takuya Yoshikawa <yoshikawa.takuya@....ntt.co.jp>, KVM list <kvm@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org> Subject: Re: [PATCH v2] KVM: cleanup {kvm_vm_ioctl, kvm}_get_dirty_log() On Wed, Mar 17, 2010 at 03:49:19PM +0800, Xiao Guangrong wrote: > Using bitmap_empty() to see whether memslot->dirty_bitmap is empty > > Changlog: > cleanup x86 specific kvm_vm_ioctl_get_dirty_log() and fix a local > parameter's type address Takuya Yoshikawa's suggestion > > Signed-off-by: Xiao Guangrong <xiaoguangrong@...fujitsu.com> > --- > arch/x86/kvm/x86.c | 17 ++++------------- > virt/kvm/kvm_main.c | 7 ++----- > 2 files changed, 6 insertions(+), 18 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index bcf52d1..e6cbbd4 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -2644,22 +2644,17 @@ static int kvm_vm_ioctl_reinject(struct kvm *kvm, > int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, > struct kvm_dirty_log *log) > { > - int r, n, i; > + int r, n, is_dirty = 0; > struct kvm_memory_slot *memslot; > - unsigned long is_dirty = 0; > unsigned long *dirty_bitmap = NULL; > > mutex_lock(&kvm->slots_lock); > > - r = -EINVAL; > - if (log->slot >= KVM_MEMORY_SLOTS) > + r = kvm_get_dirty_log(kvm, log, &is_dirty); > + if (r) > goto out; > > memslot = &kvm->memslots->memslots[log->slot]; > - r = -ENOENT; > - if (!memslot->dirty_bitmap) > - goto out; > - Its different because the user copy must be done after the SRCU assignment. > index bcd08b8..b08a7de 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -767,9 +767,7 @@ int kvm_get_dirty_log(struct kvm *kvm, > struct kvm_dirty_log *log, int *is_dirty) > { > struct kvm_memory_slot *memslot; > - int r, i; > - int n; > - unsigned long any = 0; > + int r, n, any = 0; > > r = -EINVAL; > if (log->slot >= KVM_MEMORY_SLOTS) > @@ -782,8 +780,7 @@ int kvm_get_dirty_log(struct kvm *kvm, > > n = ALIGN(memslot->npages, BITS_PER_LONG) / 8; > > - for (i = 0; !any && i < n/sizeof(long); ++i) > - any = memslot->dirty_bitmap[i]; > + any = !bitmap_empty(memslot->dirty_bitmap, memslot->npages); The opencoded version should be faster in comparison to __bitmap_empty because the dirty bitmaps are always unsigned long aligned (and also there's a function call). -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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