iommu: Take lock before reading iommu group default domain type
authorSai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Tue, 24 Nov 2020 13:06:03 +0000 (21:06 +0800)
committerWill Deacon <will@kernel.org>
Wed, 25 Nov 2020 12:14:33 +0000 (12:14 +0000)
commit0b8a96a3120ffe4d3571d93902693c59f90c3d0c
tree8d7845d5f7b08be39b68df3023ef435c3ef16707
parent08a27c1c3ecf5e1da193ce5f8fc97c3be16e75f0
iommu: Take lock before reading iommu group default domain type

"/sys/kernel/iommu_groups/<grp_id>/type" file could be read to find out the
default domain type of an iommu group. The default domain of an iommu group
doesn't change after booting and hence could be read directly. But,
after addding support to dynamically change iommu group default domain, the
above assumption no longer stays valid.

iommu group default domain type could be changed at any time by writing to
"/sys/kernel/iommu_groups/<grp_id>/type". So, take group mutex before
reading iommu group default domain type so that the user wouldn't see stale
values or iommu_group_show_type() doesn't try to derefernce stale pointers.

Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Sohil Mehta <sohil.mehta@intel.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Link: https://lore.kernel.org/r/20201124130604.2912899-4-baolu.lu@linux.intel.com
Signed-off-by: Will Deacon <will@kernel.org>
drivers/iommu/iommu.c