Re: [PATCHv4 17/28] x86/vdso: Switch image on setns()/unshare()/clone()

[Dmitry Safonov]

On 6/14/19 3:05 PM, Thomas Gleixner wrote:
> On Wed, 12 Jun 2019, Dmitry Safonov wrote:
>>  
>> +#ifdef CONFIG_TIME_NS
>> +int vdso_join_timens(struct task_struct *task)
>> +{
>> +	struct mm_struct *mm = task->mm;
>> +	struct vm_area_struct *vma;
>> +
>> +	if (down_write_killable(&mm->mmap_sem))
>> +		return -EINTR;
>> +
>> +	for (vma = mm->mmap; vma; vma = vma->vm_next) {
>> +		unsigned long size = vma->vm_end - vma->vm_start;
>> +
>> +		if (vma_is_special_mapping(vma, &vvar_mapping) ||
>> +		    vma_is_special_mapping(vma, &vdso_mapping))
>> +			zap_page_range(vma, vma->vm_start, size);
>> +	}
>> +
>> +	up_write(&mm->mmap_sem);
>> +	return 0;
>> +}
>> +#else /* CONFIG_TIME_NS */
>> +int vdso_join_timens(struct task_struct *task)
>> +{
>> +	return -ENXIO;
>> +}
> 
> Is that else path really required? The callsite is only compiled when
> CONFIG_TIME_NS is enabled, right?

Oh, yes - will drop this.

Thanks,
          Dmitry