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

[Tamas K Lengyel <tamas@xxxxxxxxxxxxx>]

On Mon, Jun 26, 2017 at 9:09 AM, Andrew Cooper
<andrew.cooper3@xxxxxxxxxx> wrote:
> On 26/06/17 15:52, Tamas K Lengyel wrote:
>> On Mon, Jun 26, 2017 at 3:48 AM, Razvan Cojocaru
>> <rcojocaru@xxxxxxxxxxxxxxx> wrote:
>>> Pending livepatch code wants to check if the vm_event wait queues
>>> are active, and this is made harder by the fact that they were
>>> previously only initialized some time after the domain was created,
>>> in vm_event_enable(). This patch initializes the lists immediately
>>> after xzalloc()ating the vm_event memory, in domain_create(), in
>>> the newly added init_domain_vm_event() function.
>>>
>>> Signed-off-by: Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>
>>> ---
>>>  xen/common/domain.c        |  5 ++---
>>>  xen/common/vm_event.c      | 23 ++++++++++++++++++++---
>>>  xen/include/xen/vm_event.h |  2 ++
>>>  3 files changed, 24 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/xen/common/domain.c b/xen/common/domain.c
>>> index b22aacc..89a8f1d 100644
>>> --- a/xen/common/domain.c
>>> +++ b/xen/common/domain.c
>>> @@ -362,11 +362,10 @@ 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 )
>>> +        if ( (err = init_domain_vm_event(d)) != 0 )
>>>              goto fail;
>>>
>>> +        err = -ENOMEM;
>>>          d->pbuf = xzalloc_array(char, DOMAIN_PBUF_SIZE);
>>>          if ( !d->pbuf )
>>>              goto fail;
>>> diff --git a/xen/common/vm_event.c b/xen/common/vm_event.c
>>> index 9291db6..294ddd7 100644
>>> --- a/xen/common/vm_event.c
>>> +++ b/xen/common/vm_event.c
>>> @@ -39,6 +39,26 @@
>>>  #define vm_event_ring_lock(_ved)       spin_lock(&(_ved)->ring_lock)
>>>  #define vm_event_ring_unlock(_ved)     spin_unlock(&(_ved)->ring_lock)
>>>
>>> +int init_domain_vm_event(struct domain *d)
>> We already have a vm_event_init_domain function so the naming of this
>> one here is not a particularly good one. It also looks like to me
>> these two functions could simply be merged..
>
> They shouldn't be merged.
>
> The current vm_event_init_domain() should probably be
> init_domain_arch_vm_event(), as it deals with constructing
> d->arch.vm_event, whereas this function deals with d->vm_event.

That would be fine for me, it's really the naming that I had a problem with.

Thanks,
Tamas

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