Hi Will, 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 <[email protected]> >> Cc: Will Deacon <[email protected]> >> Cc: Joerg Roedel <[email protected]> >> --- >> >> 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. Just code inspection, not have a platform to test this. Regards, Peng. > >Will >_______________________________________________ >iommu mailing list >[email protected] >https://lists.linuxfoundation.org/mailman/listinfo/iommu -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
