RE: [PATCH 02/16] backends/iommufd: Fix missing ERRP_GUARD() for error_prepend()

[Duan, Zhenzhong]

>-----Original Message-----
>From: Zhao Liu <zhao1.liu@linux.intel.com>
>Subject: [PATCH 02/16] backends/iommufd: Fix missing ERRP_GUARD() for
>error_prepend()
>
>From: Zhao Liu <zhao1.liu@intel.com>
>
>As the comment in qapi/error, passing @errp to error_prepend() requires
>ERRP_GUARD():
>
>* = Why, when and how to use ERRP_GUARD() =
>*
>* Without ERRP_GUARD(), use of the @errp parameter is restricted:
>...
>* - It should not be passed to error_prepend(), error_vprepend() or
>*   error_append_hint(), because that doesn't work with &error_fatal.
>* ERRP_GUARD() lifts these restrictions.
>*
>* To use ERRP_GUARD(), add it right at the beginning of the function.
>* @errp can then be used without worrying about the argument being
>* NULL or &error_fatal.
>
>ERRP_GUARD() could avoid the case when @errp is the pointer of
>error_fatal, the user can't see this additional information, because
>exit() happens in error_setg earlier than information is added [1].
>
>The iommufd_backend_set_fd() passes @errp to error_prepend(), to avoid
>the above issue, add missing ERRP_GUARD() at the beginning of this
>function.
>
>[1]: Issue description in the commit message of commit ae7c80a7bd73
>     ("error: New macro ERRP_GUARD()").
>
>Cc: Yi Liu <yi.l.liu@intel.com>
>Cc: Eric Auger <eric.auger@redhat.com>
>Cc: Zhenzhong Duan <zhenzhong.duan@intel.com>
>Signed-off-by: Zhao Liu <zhao1.liu@intel.com>

Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>

Thanks
Zhenzhong

>---
> backends/iommufd.c | 1 +
> 1 file changed, 1 insertion(+)
>
>diff --git a/backends/iommufd.c b/backends/iommufd.c
>index 1ef683c7b080..62a79fa6b049 100644
>--- a/backends/iommufd.c
>+++ b/backends/iommufd.c
>@@ -43,6 +43,7 @@ static void iommufd_backend_finalize(Object *obj)
>
> static void iommufd_backend_set_fd(Object *obj, const char *str, Error
>**errp)
> {
>+    ERRP_GUARD();
>     IOMMUFDBackend *be = IOMMUFD_BACKEND(obj);
>     int fd = -1;
>
>--
>2.34.1