On Tue, Oct 02, 2018 at 01:22:31PM +1000, Alexey Kardashevskiy wrote: > As a part of cleanup, the SPAPR TCE IOMMU subdriver releases preregistered > memory. If there is a bug in memory release, the loop in > tce_iommu_release() becomes infinite; this actually happened to me. > > This makes the loop finite and prints a warning on every failure to make > the code more bug prone. > > Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
Reviewed-by: David Gibson <da...@gibson.dropbear.id.au>
It does improve the current behaviour. I do suspect, however, that
leaving the failed regions in the list will probably cause another
failure later on.
> ---
> drivers/vfio/vfio_iommu_spapr_tce.c | 10 +++-------
> 1 file changed, 3 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c
> b/drivers/vfio/vfio_iommu_spapr_tce.c
> index b1a8ab3..ece0651 100644
> --- a/drivers/vfio/vfio_iommu_spapr_tce.c
> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c
> @@ -371,6 +371,7 @@ static void tce_iommu_release(void *iommu_data)
> {
> struct tce_container *container = iommu_data;
> struct tce_iommu_group *tcegrp;
> + struct tce_iommu_prereg *tcemem, *tmtmp;
> long i;
>
> while (tce_groups_attached(container)) {
> @@ -393,13 +394,8 @@ static void tce_iommu_release(void *iommu_data)
> tce_iommu_free_table(container, tbl);
> }
>
> - while (!list_empty(&container->prereg_list)) {
> - struct tce_iommu_prereg *tcemem;
> -
> - tcemem = list_first_entry(&container->prereg_list,
> - struct tce_iommu_prereg, next);
> - WARN_ON_ONCE(tce_iommu_prereg_free(container, tcemem));
> - }
> + list_for_each_entry_safe(tcemem, tmtmp, &container->prereg_list, next)
> + WARN_ON(tce_iommu_prereg_free(container, tcemem));
>
> tce_iommu_disable(container);
> if (container->mm)
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
signature.asc
Description: PGP signature
