lisa/android_kernel_xiaomi_sm8350
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

BACKPORT: iommu: Avoid races around device probe

Browse Source 
We currently have 3 different ways that __iommu_probe_device() may be
called, but no real guarantee that multiple callers can't tread on each
other, especially once asynchronous driver probe gets involved. It would
likely have taken a fair bit of luck to hit this previously, but commit
57365a04c921 ("iommu: Move bus setup to IOMMU device registration") ups
the odds since now it's not just omap-iommu that may trigger multiple
bus_iommu_probe() calls in parallel if probing asynchronously.

Add a lock to ensure we can't try to double-probe a device, and also
close some possible race windows to make sure we're truly robust against
trying to double-initialise a group via two different member devices.

Reported-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Tested-by: Brian Norris <briannorris@chromium.org>
Fixes: 57365a04c921 ("iommu: Move bus setup to IOMMU device registration")
Link: https://lore.kernel.org/r/1946ef9f774851732eed78760a78ec40dbc6d178.1667591503.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Bug: 269232600
(cherry picked from commit 01657bc14a3990c665375f77978631fee77b1fce)
Change-Id: Ie87f8f7a7b90431c3a2682923961885ce7b239f3
Signed-off-by: Zhenhua Huang <quic_zhenhuah@quicinc.com>
Signed-off-by: Srinivasarao Pathipati <quic_spathi@quicinc.com>
This commit is contained in:
Robin Murphy 2022-11-04 19:51:43 +00:00 committed by Srinivasarao Pathipati
parent 3daec397ee
commit 2490e55ff4
1 changed files with 18 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
drivers/iommu/iommu.c
View File

@ -177,14 +177,25 @@ static void iommu_free_dev_param(struct device *dev)
int iommu_probe_device(struct device *dev)
{
const struct iommu_ops *ops = dev->bus->iommu_ops;
static DEFINE_MUTEX(iommu_probe_device_lock);
int ret;
WARN_ON(dev->iommu_group);
if (!ops)
return -EINVAL;
if (!iommu_get_dev_param(dev))
return -ENOMEM;
/*
* Serialise to avoid races between IOMMU drivers registering in
* parallel and/or the "replay" calls from ACPI/OF code via client
* driver probe. Once the latter have been cleaned up we should
* probably be able to use device_lock() here to minimise the scope,
* but for now enforcing a simple global ordering is fine.
*/
mutex_lock(&iommu_probe_device_lock);
if (!iommu_get_dev_param(dev)) {
ret = -ENOMEM;
goto err_unlock;
}
if (!try_module_get(ops->owner)) {
ret = -EINVAL;
@ -195,12 +206,17 @@ int iommu_probe_device(struct device *dev)
if (ret)
goto err_module_put;
mutex_unlock(&iommu_probe_device_lock);
return 0;
err_module_put:
module_put(ops->owner);
err_free_dev_param:
iommu_free_dev_param(dev);
err_unlock:
mutex_unlock(&iommu_probe_device_lock);
return ret;
}