> -----Original Message----- > From: Alex Williamson [mailto:alex.williamson@xxxxxxxxxx] > Sent: Monday, February 19, 2018 7:51 PM > To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@xxxxxxxxxx> > Cc: eric.auger@xxxxxxxxxx; pmorel@xxxxxxxxxxxxxxxxxx; > kvm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Linuxarm > <linuxarm@xxxxxxxxxx>; John Garry <john.garry@xxxxxxxxxx>; xuwei (O) > <xuwei5@xxxxxxxxxx> > Subject: Re: [PATCH v3 1/6] vfio/type1: Introduce iova list and add iommu > aperture validity check > > On Mon, 19 Feb 2018 09:50:24 +0000 > Shameerali Kolothum Thodi <shameerali.kolothum.thodi@xxxxxxxxxx> wrote: > > > -----Original Message----- > > > From: Alex Williamson [mailto:alex.williamson@xxxxxxxxxx] > > > Sent: Friday, February 16, 2018 8:49 PM > > > On Thu, 15 Feb 2018 09:44:59 +0000 > > > Shameer Kolothum <shameerali.kolothum.thodi@xxxxxxxxxx> wrote: > > > > + node->end = end; > > > > + continue; > > > > + } > > > > + /* Delete nodes after new end */ > > > > + list_del(&node->list); > > > > + kfree(node); > > > > + } > > > > + > > > > + return 0; > > > > +} > > > > + > > > > +static int vfio_iommu_get_iova_copy(struct vfio_iommu *iommu, > > > > + struct list_head *iova_copy) > > > > +{ > > > > + > > > > + struct list_head *iova = &iommu->iova_list; > > > > + struct vfio_iova *n; > > > > + > > > > + list_for_each_entry(n, iova, list) { > > > > + int ret; > > > > + > > > > + ret = vfio_insert_iova(n->start, n->end, iova_copy); > > > > + if (ret) > > > > + return ret; > > > > > > Let's delete and free any entries added to the copy here too. > > > > Ok. My original thought was caller will free up in case of error. > > This comes down to Rusty's suggestions of how to make an API hard to > misuse rather than simply easy to use to me. Placing the onus on the > caller to cleanup a list sounds simple, but the caller passed an empty > list and the function failed, why should the caller bother to check if > the function left any cruft on the list in the course of failing? This > is not a hard to misuse interface, in fact it's very easy to forget > that cleanup. Thanks, Ok. I understand the concerns. I will sent out a revised one soon. Thanks, Shameer
