On Wed, Nov 04, 2015 at 10:48:28AM +0800, Peng Fan wrote: > On Tue, Nov 03, 2015 at 01:17:34PM +0000, Will Deacon wrote: > >On Tue, Nov 03, 2015 at 08:59:17PM +0800, Peng Fan wrote: > >> iommu_group_alloc will initialize the reference count for group to 1. > >> iommu_group_add_device also increase the group reference count, > >> if nothing bad happends. And we need to add iommu_group_put to > >> decrease the reference count for group. > >> > >> Signed-off-by: Peng Fan <van.free...@gmail.com> > >> Cc: Will Deacon <will.dea...@arm.com> > >> Cc: Joerg Roedel <j...@8bytes.org> > >> --- > >> > >> Not sure whether my understanding is correct or not. I checked > >> rockchip-iommu.c > >> exynos-iommu.c and fsl_pamu_domain.c, and they all have iommu_group_put > >> after > >> iommu_group_add_device. > > > >Doesn't this pair up with the iommu_group_remove_device in > >arm_smmu_remove_device? Are you actually seeing an issue in practice? > > In arm_smmu_add_platform_device, > iommu_group_alloc --> group->device_kobj ref count will be init to 1. > iommu_group_add_device --> group->device_kobj ref count will be added 1 to 2. > > In arm_smmu_remove_device: > iommu_group_remove_device --> Decrease group->device_kobj ref count by 1. > After arm_smmu_remove_device, the ref count of group->device_kobj is not 0. > > So I think need to add iommu_group_put after iommu_group_add_device. > If I am wrong, please correct me.
Ok, I see what you're saying. iommu_group_get_for_dev has exactly the same issue, so could you update arm-smmu-v3.c as well, please? Thanks, Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
