[libvirt] [PATCH 5/6] libxl: Add refcnt for args->conn during migration

Erik Skultety eskultet at redhat.com
Thu May 3 12:34:44 UTC 2018


On Tue, Apr 24, 2018 at 08:28:08AM -0400, John Ferlan wrote:
> Since the @dconn reference via args->conn will be used via a thread
> or callback, let's make sure memory associated with it isn't free'd
> unexpectedly before we use it. The Unref will be done when the object
> is Dispose'd.
>
> Signed-off-by: John Ferlan <jferlan at redhat.com>
> ---
>  src/libxl/libxl_migration.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/src/libxl/libxl_migration.c b/src/libxl/libxl_migration.c
> index 7fe352306c..d37a4a687a 100644
> --- a/src/libxl/libxl_migration.c
> +++ b/src/libxl/libxl_migration.c
> @@ -239,6 +239,7 @@ libxlMigrationDstArgsDispose(void *obj)
>
>      libxlMigrationCookieFree(args->migcookie);
>      VIR_FREE(args->socks);
> +    virObjectUnref(args->conn);
>      virObjectUnref(args->vm);
>  }
>
> @@ -608,7 +609,7 @@ libxlDomainMigrationDstPrepareTunnel3(virConnectPtr dconn,
>      if (!(args = virObjectNew(libxlMigrationDstArgsClass)))
>          goto error;
>
> -    args->conn = dconn;
> +    args->conn = virObjectRef(dconn);
>      args->vm = virObjectRef(vm);
>      args->flags = flags;
>      args->migcookie = mig;
> @@ -763,7 +764,7 @@ libxlDomainMigrationDstPrepare(virConnectPtr dconn,
>      if (!(args = virObjectNew(libxlMigrationDstArgsClass)))
>          goto error;
>
> -    args->conn = dconn;
> +    args->conn = virObjectRef(dconn);
>      args->vm = virObjectRef(vm);
>      args->flags = flags;
>      args->socks = socks;

Do you actually have a use case, where the conn object would be destroyed
before the migration finishes in a way that this could cause a SIGSEGV?

Erik




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