[libvirt] [PATCH 2/2] qemu: Avoid deadlock in autodestroy

[Michal Privoznik]

On 18.02.2013 17:07, Jiri Denemark wrote:
> Since closeCallbacks were turned into virObjectLockable, we can no
> longer call virQEMUCloseCallbacks APIs from within a registered close
> callback.
> ---
>  src/qemu/qemu_conf.c    | 19 ++++---------------
>  src/qemu/qemu_conf.h    |  4 ++++
>  src/qemu/qemu_domain.h  |  1 +
>  src/qemu/qemu_process.c | 10 +++++++++-
>  4 files changed, 18 insertions(+), 16 deletions(-)
> 
> diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
> index edadf36..fc8e152 100644
> --- a/src/qemu/qemu_conf.c
> +++ b/src/qemu/qemu_conf.c
> @@ -825,8 +825,6 @@ virQEMUCloseCallbacksRunOne(void *payload,
>  {
>      struct virQEMUCloseCallbacksData *data = opaque;
>      qemuDriverCloseDefPtr closeDef = payload;
> -    unsigned char uuid[VIR_UUID_BUFLEN];
> -    char uuidstr[VIR_UUID_STRING_BUFLEN];
>      virDomainObjPtr dom;
>  
>      VIR_DEBUG("conn=%p, thisconn=%p, uuid=%s, cb=%p",
> @@ -835,18 +833,9 @@ virQEMUCloseCallbacksRunOne(void *payload,
>      if (data->conn != closeDef->conn || !closeDef->cb)
>          return;
>  
> -    if (virUUIDParse(name, uuid) < 0) {
> -        VIR_WARN("Failed to parse %s", (const char *)name);
> -        return;
> -    }
> -    /* We need to reformat uuidstr, because closeDef->cb
> -     * might cause the current hash entry to be removed,
> -     * which means 'name' will have been free()d
> -     */
> -    virUUIDFormat(uuid, uuidstr);
> -
> -    if (!(dom = virDomainObjListFindByUUID(data->driver->domains, uuid))) {
> -        VIR_DEBUG("No domain object with UUID %s", uuidstr);
> +    if (!(dom = virDomainObjListFindByUUID(data->driver->domains, name))) {
> +        VIR_DEBUG("No domain object with UUID %s",
> +                  (const char *) name);

No. Please s/name/uuid/ as storing UUID into variable named @name is
insane. Or do we want to confuse an enemy? :) I know you haven't
introduced it, but since you are touching the body anyway, it's worth
changing the parameter name as well.

>          return;
>      }
>  
> @@ -854,7 +843,7 @@ virQEMUCloseCallbacksRunOne(void *payload,
>      if (dom)
>          virObjectUnlock(dom);
>  
> -    virHashRemoveEntry(data->list, uuidstr);
> +    virHashRemoveEntry(data->list, name);
>  }
>  

ACK if you change the variable name.

Michal