Messages in this thread | | | Date | Fri, 13 Oct 2017 15:35:16 +0200 | From | Christoffer Dall <> | Subject | Re: [PATCH v2 07/10] KVM: arm/arm64: vgic-its: new helper functions to free the caches |
| |
On Wed, Sep 27, 2017 at 03:28:37PM +0200, Eric Auger wrote: > From: wanghaibin <wanghaibin.wang@huawei.com> > > We create 2 new functions that frees the device and
two free
> collection lists. this is currently called by vgic_its_destroy()
These are
> and we will add other callers in subsequent patches. > > We also remove the check on its->device_list.next as it looks > unnecessary:
Could you elude to why you're doing this in the first place in the next version of the commit message? Thanks.
> > The kvm device is removed by kvm_destroy_devices which loops on > all the devices added to kvm->devices. kvm_ioctl_create_device > only adds the device to kvm_devices once the lists have been > initialized (in vgic_create_its).
I don't understand what this paragraph is trying to tell me beyond what some code already does irrelevant to this patch?
> > We also move vgic_its_free_device to prepare for new callers. > > Signed-off-by: wanghaibin <wanghaibin.wang@huawei.com> > Signed-off-by: Eric Auger <eric.auger@redhat.com> > > --- > [Eric] removed its->device_list.next which is not needed as > pointed out by Wanghaibin. Reword the commit message > --- > virt/kvm/arm/vgic/vgic-its.c | 76 ++++++++++++++++++++++++-------------------- > 1 file changed, 41 insertions(+), 35 deletions(-) > > diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c > index 9e6b556..0df6d5f 100644 > --- a/virt/kvm/arm/vgic/vgic-its.c > +++ b/virt/kvm/arm/vgic/vgic-its.c > @@ -611,6 +611,45 @@ static void its_free_ite(struct kvm *kvm, struct its_ite *ite) > kfree(ite); > } > > +static void vgic_its_free_device(struct kvm *kvm, struct its_device *dev) > +{ > + struct its_ite *ite, *tmp; > + > + list_for_each_entry_safe(ite, tmp, &dev->itt_head, ite_list) > + its_free_ite(kvm, ite); > + list_del(&dev->dev_list); > + kfree(dev); > +} > + > +static void vgic_its_free_device_list(struct kvm *kvm, struct vgic_its *its) > +{ > + struct list_head *cur, *temp; > + > + mutex_lock(&its->its_lock); > + list_for_each_safe(cur, temp, &its->device_list) { > + struct its_device *dev; > + > + dev = list_entry(cur, struct its_device, dev_list); > + vgic_its_free_device(kvm, dev); > + } > + mutex_unlock(&its->its_lock);
this changes semantics from locking across freeing both devices and collections to taking the locks separately. Is that valid?
> +} > + > +static void vgic_its_free_collection_list(struct kvm *kvm, struct vgic_its *its) > +{ > + struct list_head *cur, *temp; > + > + list_for_each_safe(cur, temp, &its->collection_list) { > + struct its_collection *coll; > + > + coll = list_entry(cur, struct its_collection, coll_list); > + list_del(cur); > + kfree(coll); > + } > + mutex_unlock(&its->its_lock);
no mutex_lock ?
> +} > + > + > static u64 its_cmd_mask_field(u64 *its_cmd, int word, int shift, int size) > { > return (le64_to_cpu(its_cmd[word]) >> shift) & (BIT_ULL(size) - 1); > @@ -1634,46 +1673,13 @@ static int vgic_its_create(struct kvm_device *dev, u32 type) > return vgic_its_set_abi(its, NR_ITS_ABIS - 1); > } > > -static void vgic_its_free_device(struct kvm *kvm, struct its_device *dev) > -{ > - struct its_ite *ite, *tmp; > - > - list_for_each_entry_safe(ite, tmp, &dev->itt_head, ite_list) > - its_free_ite(kvm, ite); > - list_del(&dev->dev_list); > - kfree(dev); > -} > - > static void vgic_its_destroy(struct kvm_device *kvm_dev) > { > struct kvm *kvm = kvm_dev->kvm; > struct vgic_its *its = kvm_dev->private; > - struct list_head *cur, *temp; > - > - /* > - * We may end up here without the lists ever having been initialized. > - * Check this and bail out early to avoid dereferencing a NULL pointer. > - */ > - if (!its->device_list.next) > - return;
I don't think this is valid. We can actually have a non-initialized list and without this check, list_for_each_entry_safe in vgic_its_free_device_list will crash the kernel.
Note that an initialized empty list_head doesn't have head and tail pointing to NULL, but pointing to the list_head itself.
> - > - mutex_lock(&its->its_lock); > - list_for_each_safe(cur, temp, &its->device_list) { > - struct its_device *dev; > - > - dev = list_entry(cur, struct its_device, dev_list); > - vgic_its_free_device(kvm, dev); > - } > - > - list_for_each_safe(cur, temp, &its->collection_list) { > - struct its_collection *coll; > - > - coll = list_entry(cur, struct its_collection, coll_list); > - list_del(cur); > - kfree(coll); > - } > - mutex_unlock(&its->its_lock); > > + vgic_its_free_device_list(kvm, its); > + vgic_its_free_collection_list(kvm, its); > kfree(its); > } > > -- > 2.5.5 >
Thanks, -Christoffer
| |