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Re: [libvirt] [PATCH 8/9] Fix locking wrt virNetClientStreamPtr object



On 06/28/2011 11:01 AM, Daniel P. Berrange wrote:
> The client stream object can be used independantly of the

s/independantly/independently/

> virNetClientPtr object, so must have full locking of its
> own and not rely on any caller.
> 
> * src/remote/remote_driver.c: Remove locking around stream
>   callback
> * src/rpc/virnetclientstream.c: Add locking to all APIs
>   and callbacks
> ---
>  src/remote/remote_driver.c   |    3 -
>  src/rpc/virnetclientstream.c |  112 +++++++++++++++++++++++++++++++++---------
>  2 files changed, 89 insertions(+), 26 deletions(-)
> 
> @@ -390,20 +435,23 @@ int virNetClientStreamEventAddCallback(virNetClientStreamPtr st,
>                                         void *opaque,
>                                         virFreeCallback ff)
>  {
> +    int ret = -1;
> +
> +    virMutexLock(&st->lock);
>      if (st->cb) {
>          virNetError(VIR_ERR_INTERNAL_ERROR,
>                      "%s", _("multiple stream callbacks not supported"));
> -        return 1;
> +        goto cleanup;
>      }
>  
> -    virNetClientStreamRef(st);
> +    st->refs++;
>      if ((st->cbTimer =
>           virEventAddTimeout(-1,
>                              virNetClientStreamEventTimer,
>                              st,
>                              virNetClientStreamEventTimerFree)) < 0) {
> -        virNetClientStreamFree(st);
> -        return -1;
> +        st->refs--;
> +        goto cleanup;
>      }

This increments st->refs on success,

>  int virNetClientStreamEventRemoveCallback(virNetClientStreamPtr st)
>  {
> +    int ret = -1;
> +
> +    virMutexUnlock(&st->lock);
>      if (!st->cb) {
>          virNetError(VIR_ERR_INTERNAL_ERROR,
>                      "%s", _("no stream callback registered"));
> -        return -1;
> +        goto cleanup;
>      }
>  
>      if (!st->cbDispatch &&

but nothing here ever decrements it.

That looks like the only flaw; so ACK if you fix things to guarantee no
leaked st on a paired callback add/remove.

-- 
Eric Blake   eblake redhat com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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