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"/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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.