diff options
author | Robin Murphy <robin.murphy@arm.com> | 2022-11-04 22:51:43 +0300 |
---|---|---|
committer | Joerg Roedel <jroedel@suse.de> | 2022-11-19 12:17:42 +0300 |
commit | 01657bc14a3990c665375f77978631fee77b1fce (patch) | |
tree | 3328773667b49e9c7b8ef9c84c474982c95ec50c /drivers/iommu | |
parent | 69e61edebea030f177de7a23b8d5d9b8c4a90bda (diff) | |
download | linux-01657bc14a3990c665375f77978631fee77b1fce.tar.xz |
iommu: Avoid races around device probe
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>
Diffstat (limited to 'drivers/iommu')
-rw-r--r-- | drivers/iommu/iommu.c | 28 |
1 files changed, 22 insertions, 6 deletions
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 6ca377f4fbf9..7c99d8eb3182 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -306,13 +306,23 @@ static int __iommu_probe_device(struct device *dev, struct list_head *group_list const struct iommu_ops *ops = dev->bus->iommu_ops; struct iommu_device *iommu_dev; struct iommu_group *group; + static DEFINE_MUTEX(iommu_probe_device_lock); int ret; if (!ops) return -ENODEV; - - if (!dev_iommu_get(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 (!dev_iommu_get(dev)) { + ret = -ENOMEM; + goto err_unlock; + } if (!try_module_get(ops->owner)) { ret = -EINVAL; @@ -333,11 +343,14 @@ static int __iommu_probe_device(struct device *dev, struct list_head *group_list ret = PTR_ERR(group); goto out_release; } - iommu_group_put(group); + mutex_lock(&group->mutex); if (group_list && !group->default_domain && list_empty(&group->entry)) list_add_tail(&group->entry, group_list); + mutex_unlock(&group->mutex); + iommu_group_put(group); + mutex_unlock(&iommu_probe_device_lock); iommu_device_link(iommu_dev, dev); return 0; @@ -352,6 +365,9 @@ out_module_put: err_free: dev_iommu_free(dev); +err_unlock: + mutex_unlock(&iommu_probe_device_lock); + return ret; } @@ -1824,11 +1840,11 @@ int bus_iommu_probe(struct bus_type *bus) return ret; list_for_each_entry_safe(group, next, &group_list, entry) { + mutex_lock(&group->mutex); + /* Remove item from the list */ list_del_init(&group->entry); - mutex_lock(&group->mutex); - /* Try to allocate default domain */ probe_alloc_default_domain(bus, group); |