On 2/29/24 15:39, Zhao Liu wrote:
> 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].
>
> In hw/vfio/helpers.c, there're 3 functions passing @errp to
> error_prepend() without ERRP_GUARD():
> - vfio_set_irq_signaling()
> - vfio_device_get_name()
> - vfio_device_set_fd()
>
> As the widely used helpers, their @errp parameters are so widely sourced
> that it is necessary to protect them with ERRP_GUARD().
>
> To avoid the issue like [1] said, add missing ERRP_GUARD() at their
> beginning.
>
> [1]: Issue description in the commit message of commit ae7c80a7bd73
> ("error: New macro ERRP_GUARD()").
>
> Cc: Alex Williamson <alex.williamson@redhat.com>
> Cc: "Cédric Le Goater" <clg@redhat.com>
> Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Thanks,
C.
> ---
> hw/vfio/helpers.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/hw/vfio/helpers.c b/hw/vfio/helpers.c
> index 678987080228..47b4096c05ee 100644
> --- a/hw/vfio/helpers.c
> +++ b/hw/vfio/helpers.c
> @@ -110,6 +110,7 @@ static const char *index_to_str(VFIODevice *vbasedev, int index)
> int vfio_set_irq_signaling(VFIODevice *vbasedev, int index, int subindex,
> int action, int fd, Error **errp)
> {
> + ERRP_GUARD();
> struct vfio_irq_set *irq_set;
> int argsz, ret = 0;
> const char *name;
> @@ -613,6 +614,7 @@ bool vfio_has_region_cap(VFIODevice *vbasedev, int region, uint16_t cap_type)
>
> int vfio_device_get_name(VFIODevice *vbasedev, Error **errp)
> {
> + ERRP_GUARD();
> struct stat st;
>
> if (vbasedev->fd < 0) {
> @@ -644,6 +646,7 @@ int vfio_device_get_name(VFIODevice *vbasedev, Error **errp)
>
> void vfio_device_set_fd(VFIODevice *vbasedev, const char *str, Error **errp)
> {
> + ERRP_GUARD();
> int fd = monitor_fd_param(monitor_cur(), str, errp);
>
> if (fd < 0) {