Re: [Xen-devel] [PATCH v5] common/vm_event: Initialize vm_event lists on domain creation

[Tamas K Lengyel <tamas@xxxxxxxxxxxxx>]

On Tue, Aug 29, 2017 at 9:59 AM, Wei Liu <wei.liu2@xxxxxxxxxx> wrote:
> On Tue, Aug 29, 2017 at 05:17:05PM +0300, Alexandru Isaila wrote:
> [...]
>>
>>  /**
>> diff --git a/xen/common/domain.c b/xen/common/domain.c
>> index b22aacc..30f507b 100644
>> --- a/xen/common/domain.c
>> +++ b/xen/common/domain.c
>> @@ -363,9 +363,6 @@ struct domain *domain_create(domid_t domid, unsigned int 
>> domcr_flags,
>>          poolid = 0;
>>
>>          err = -ENOMEM;
>> -        d->vm_event = xzalloc(struct vm_event_per_domain);
>> -        if ( !d->vm_event )
>> -            goto fail;
>>
>>          d->pbuf = xzalloc_array(char, DOMAIN_PBUF_SIZE);
>>          if ( !d->pbuf )
>> @@ -403,7 +400,6 @@ struct domain *domain_create(domid_t domid, unsigned int 
>> domcr_flags,
>>      if ( hardware_domain == d )
>>          hardware_domain = old_hwdom;
>>      atomic_set(&d->refcnt, DOMAIN_DESTROYED);
>> -    xfree(d->vm_event);
>>      xfree(d->pbuf);
>>      if ( init_status & INIT_arch )
>>          arch_domain_destroy(d);
>> @@ -820,7 +816,14 @@ static void complete_domain_destroy(struct rcu_head 
>> *head)
>>      free_xenoprof_pages(d);
>>  #endif
>>
>> -    xfree(d->vm_event);
>> +#ifdef CONFIG_HAS_MEM_PAGING
>> +    xfree(d->vm_event_paging);
>> +#endif
>> +    xfree(d->vm_event_monitor);
>
> Why do you unconditionally xfree these vm_event_monitor while you don't
> unconditionally allocate them?
>
> Not that this is strictly a bug but this deviates from the original
> behaviour.

Isn't xfree NULL safe?

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