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 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..

> +{
> +    d->vm_event = xzalloc(struct vm_event_per_domain);
> +
> +    if ( !d->vm_event )
> +        return -ENOMEM;
> +
> +#ifdef CONFIG_HAS_MEM_PAGING
> +    init_waitqueue_head(&d->vm_event->paging.wq);
> +#endif
> +
> +    init_waitqueue_head(&d->vm_event->monitor.wq);

Move this one up before the #ifdef block for MEM_PAGING.

> +
> +#ifdef CONFIG_HAS_MEM_SHARING
> +    init_waitqueue_head(&d->vm_event->share.wq);
> +#endif
> +
> +    return 0;
> +}
> +
>  static int vm_event_enable(
>      struct domain *d,
>      xen_domctl_vm_event_op_t *vec,
> @@ -93,9 +113,6 @@ static int vm_event_enable(
>      /* Save the pause flag for this particular ring. */
>      ved->pause_flag = pause_flag;
>
> -    /* Initialize the last-chance wait queue. */
> -    init_waitqueue_head(&ved->wq);
> -
>      vm_event_ring_unlock(ved);
>      return 0;
>
> diff --git a/xen/include/xen/vm_event.h b/xen/include/xen/vm_event.h
> index 2fb3951..482243e 100644
> --- a/xen/include/xen/vm_event.h
> +++ b/xen/include/xen/vm_event.h
> @@ -80,6 +80,8 @@ void vm_event_set_registers(struct vcpu *v, 
> vm_event_response_t *rsp);
>
>  void vm_event_monitor_next_interrupt(struct vcpu *v);
>
> +int init_domain_vm_event(struct domain *d);
> +
>  #endif /* __VM_EVENT_H__ */
>
>  /*
> --
> 1.9.1

Tamas

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