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SubjectRe: [PATCH] KVM: Add the check and free to avoid unknown errors.
linmiaohe <linmiaohe@huawei.com> 于2020年2月15日周六 上午10:00写道:
>
> Hi:
> Haiwei Li <lihaiwei.kernel@gmail.com> wrote:
> > From: Haiwei Li <lihaiwei@tencent.com>
> >
> > If 'kvm_create_vm_debugfs()' fails in 'kzalloc(sizeof(*stat_data), ...)', 'kvm_destroy_vm_debugfs()' will be called by the final fput(file) in 'kvm_dev_ioctl_create_vm()'.
> >
> > Add the check and free to avoid unknown errors.
>
> Add the check and free? According to the code,it seem what you mean is "add the check against free" ?

Right, i can change the description.

>
> >
> > Signed-off-by: Haiwei Li <lihaiwei@tencent.com>
> >
> > if (kvm->debugfs_stat_data) {
> > - for (i = 0; i < kvm_debugfs_num_entries; i++)
> > + for (i = 0; i < kvm_debugfs_num_entries; i++) {
> > + if (!kvm->debugfs_stat_data[i])
> > + break;
> > kfree(kvm->debugfs_stat_data[i]);
> > + }
> > kfree(kvm->debugfs_stat_data);
> > }
> > }
>
> If (!kvm->debugfs_stat_data[i]) is checked in kfree() internal. And break early seems have no different effect.
> Could you please explain what unknown errors may occur? And how? Thanks.

I get the free() code. It is just like what you said. Thanks a lot.
Break early is useful. If kvm->debugfs_stat_data[i] is null, breaking
early can reduce the check.

>

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