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iommu: Simplify the __iommu_group_remove_device() flow

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Instead of returning the struct group_device and then later freeing it, do
the entire free under the group->mutex and defer only putting the
iommu_group.

It is safe to remove the sysfs_links and free memory while holding that
mutex.

Move the sanity assert of the group status into
__iommu_group_free_device().

The next patch will improve upon this and consolidate the group put and
the mutex into __iommu_group_remove_device().

__iommu_group_free_device() is close to being the paired undo of
iommu_group_add_device(), following patches will improve on that.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/4-v3-328044aa278c+45e49-iommu_probe_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Jason Gunthorpe 2023-06-05 21:59:42 -03:00 committed by Joerg Roedel
parent 7bdb99622f
commit df15d76dca
1 changed files with 39 additions and 44 deletions
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83
drivers/iommu/iommu.c
View file

@ -470,32 +470,8 @@ int iommu_probe_device(struct device *dev)
}
/*
* Remove a device from a group's device list and return the group device
* if successful.
*/
static struct group_device *
__iommu_group_remove_device(struct iommu_group *group, struct device *dev)
{
struct group_device *device;
lockdep_assert_held(&group->mutex);
for_each_group_device(group, device) {
if (device->dev == dev) {
list_del(&device->list);
return device;
}
}
return NULL;
}
/*
* Release a device from its group and decrements the iommu group reference
* count.
*/
static void __iommu_group_release_device(struct iommu_group *group,
struct group_device *grp_dev)
static void __iommu_group_free_device(struct iommu_group *group,
struct group_device *grp_dev)
{
struct device *dev = grp_dev->dev;
@ -504,16 +480,45 @@ static void __iommu_group_release_device(struct iommu_group *group,
trace_remove_device_from_group(group->id, dev);
/*
* If the group has become empty then ownership must have been
* released, and the current domain must be set back to NULL or
* the default domain.
*/
if (list_empty(&group->devices))
WARN_ON(group->owner_cnt ||
group->domain != group->default_domain);
kfree(grp_dev->name);
kfree(grp_dev);
dev->iommu_group = NULL;
iommu_group_put(group);
}
/*
* Remove the iommu_group from the struct device. The attached group must be put
* by the caller after releaseing the group->mutex.
*/
static void __iommu_group_remove_device(struct device *dev)
{
struct iommu_group *group = dev->iommu_group;
struct group_device *device;
lockdep_assert_held(&group->mutex);
for_each_group_device(group, device) {
if (device->dev != dev)
continue;
list_del(&device->list);
__iommu_group_free_device(group, device);
/* Caller must put iommu_group */
return;
}
WARN(true, "Corrupted iommu_group device_list");
}
static void iommu_release_device(struct device *dev)
{
struct iommu_group *group = dev->iommu_group;
struct group_device *device;
const struct iommu_ops *ops;
if (!dev->iommu || !group)
@ -522,16 +527,7 @@ static void iommu_release_device(struct device *dev)
iommu_device_unlink(dev->iommu->iommu_dev, dev);
mutex_lock(&group->mutex);
device = __iommu_group_remove_device(group, dev);
/*
* If the group has become empty then ownership must have been released,
* and the current domain must be set back to NULL or the default
* domain.
*/
if (list_empty(&group->devices))
WARN_ON(group->owner_cnt ||
group->domain != group->default_domain);
__iommu_group_remove_device(dev);
/*
* release_device() must stop using any attached domain on the device.
@ -547,8 +543,8 @@ static void iommu_release_device(struct device *dev)
ops->release_device(dev);
mutex_unlock(&group->mutex);
if (device)
__iommu_group_release_device(group, device);
/* Pairs with the get in iommu_group_add_device() */
iommu_group_put(group);
module_put(ops->owner);
dev_iommu_free(dev);
@ -1107,7 +1103,6 @@ EXPORT_SYMBOL_GPL(iommu_group_add_device);
void iommu_group_remove_device(struct device *dev)
{
struct iommu_group *group = dev->iommu_group;
struct group_device *device;
if (!group)
return;
@ -1115,11 +1110,11 @@ void iommu_group_remove_device(struct device *dev)
dev_info(dev, "Removing from iommu group %d\n", group->id);
mutex_lock(&group->mutex);
device = __iommu_group_remove_device(group, dev);
__iommu_group_remove_device(dev);
mutex_unlock(&group->mutex);
if (device)
__iommu_group_release_device(group, device);
/* Pairs with the get in iommu_group_add_device() */
iommu_group_put(group);
}
EXPORT_SYMBOL_GPL(iommu_group_remove_device);