Hi Will, On Fri, Nov 06, 2015 at 12:23:39PM +0000, Will Deacon wrote: >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 <[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. > >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?
I did not see the update about device_group for iommu, when I worked out this patch. Rebased to latest linux/master, whether to arm-smmu.c or arm-smmu-v3.c, only add 'iommu_group_put' at the end of iommu_group_get_for_dev is ok as the following. I'll send out V2. Thanks, Peng. > >Thanks, > >Will -- 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/
