From: Ashok Raj <ashok.raj@intel.com>
To: Joerg Roedel <joro@8bytes.org>, iommu@lists.linux-foundation.org
Cc: Ashok Raj <ashok.raj@intel.com>,
Will Deacon <will.deacon@arm.com>,
Robin Murphy <robin.murphy@arm.com>,
Christoph Hellwig <hch@lst.de>
Subject: [Patch V8 2/3] iommu: Take lock before reading iommu group default domain type
Date: Fri, 25 Sep 2020 12:06:19 -0700 [thread overview]
Message-ID: <20200925190620.18732-3-ashok.raj@intel.com> (raw)
In-Reply-To: <20200925190620.18732-1-ashok.raj@intel.com>
From: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
"/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.
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: Lu Baolu <baolu.lu@linux.intel.com>
Cc: Sohil Mehta <sohil.mehta@intel.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
---
drivers/iommu/iommu.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 2e93c48ce248..b540ae1e679d 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -501,6 +501,7 @@ static ssize_t iommu_group_show_type(struct iommu_group *group,
{
char *type = "unknown\n";
+ mutex_lock(&group->mutex);
if (group->default_domain) {
switch (group->default_domain->type) {
case IOMMU_DOMAIN_BLOCKED:
@@ -517,6 +518,7 @@ static ssize_t iommu_group_show_type(struct iommu_group *group,
break;
}
}
+ mutex_unlock(&group->mutex);
strcpy(buf, type);
return strlen(type);
--
2.7.4
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next prev parent reply other threads:[~2020-09-25 19:06 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-25 19:06 [Patch V8 0/3] iommu: Add support to change default domain of an iommu group Ashok Raj
2020-09-25 19:06 ` [Patch V8 1/3] " Ashok Raj
2020-11-18 13:51 ` Will Deacon
2020-11-19 2:18 ` Lu Baolu
2020-11-19 8:53 ` Will Deacon
2020-11-20 2:11 ` Lu Baolu
2020-11-20 11:03 ` Will Deacon
2020-11-20 11:27 ` Shameerali Kolothum Thodi
2020-11-20 13:09 ` Lu Baolu
2020-09-25 19:06 ` Ashok Raj [this message]
2020-09-25 19:06 ` [Patch V8 3/3] iommu: Document usage of "/sys/kernel/iommu_groups/<grp_id>/type" file Ashok Raj
2020-11-18 13:51 ` Will Deacon
2020-11-19 2:32 ` Lu Baolu
2020-11-19 8:55 ` Will Deacon
2020-11-20 2:13 ` Lu Baolu
2020-10-01 12:58 ` [Patch V8 0/3] iommu: Add support to change default domain of an iommu group Joerg Roedel
2020-10-01 13:51 ` Raj, Ashok
2020-11-18 13:52 ` Will Deacon
2020-11-19 2:36 ` Lu Baolu
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