Commit fa082803 authored by Jason Gunthorpe's avatar Jason Gunthorpe Committed by Joerg Roedel
Browse files

iommu: Split iommu_group_add_device() 



Move the list_add_tail() for the group_device into the critical region
that immediately follows in __iommu_probe_device(). This avoids one case
of unlocking and immediately re-locking the group->mutex.

Consistently make the caller responsible for setting dev->iommu_group,
prior patches moved this into iommu_init_device(), make the no-driver path
do this in iommu_group_add_device().

This completes making __iommu_group_free_device() and
iommu_group_alloc_device() into pair'd functions.

Reviewed-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: default avatarKevin Tian <kevin.tian@intel.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/9-v3-328044aa278c+45e49-iommu_probe_jgg@nvidia.com


Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent cfb6ee65

drivers/iommu/iommu.c

+43 −23
Original line number Diff line number Diff line
@@ -129,6 +129,8 @@ static int iommu_create_device_direct_mappings(struct iommu_domain *domain, 
					       struct device *dev);

static ssize_t iommu_group_store_type(struct iommu_group *group,

				      const char *buf, size_t count);

static struct group_device *iommu_group_alloc_device(struct iommu_group *group,

						     struct device *dev);



#define IOMMU_GROUP_ATTR(_name, _mode, _show, _store)		\

struct iommu_group_attribute iommu_group_attr_##_name =		\
@@ -435,6 +437,7 @@ static int __iommu_probe_device(struct device *dev, struct list_head *group_list 
	const struct iommu_ops *ops = dev->bus->iommu_ops;

	struct iommu_group *group;

	static DEFINE_MUTEX(iommu_probe_device_lock);

	struct group_device *gdev;

	int ret;



	if (!ops)
@@ -459,16 +462,17 @@ static int __iommu_probe_device(struct device *dev, struct list_head *group_list 
		goto out_unlock;



	group = dev->iommu_group;

	ret = iommu_group_add_device(group, dev);

	gdev = iommu_group_alloc_device(group, dev);

	mutex_lock(&group->mutex);

	if (ret)

	if (IS_ERR(gdev)) {

		ret = PTR_ERR(gdev);

		goto err_put_group;

	}



	list_add_tail(&gdev->list, &group->devices);

	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);



	return 0;
@@ -578,7 +582,10 @@ static void __iommu_group_remove_device(struct device *dev) 
	}

	mutex_unlock(&group->mutex);



	/* Pairs with the get in iommu_group_add_device() */

	/*

	 * Pairs with the get in iommu_init_device() or

	 * iommu_group_add_device()

	 */

	iommu_group_put(group);

}
@@ -1067,22 +1074,16 @@ static int iommu_create_device_direct_mappings(struct iommu_domain *domain, 
	return ret;

}



/**

 * iommu_group_add_device - add a device to an iommu group

 * @group: the group into which to add the device (reference should be held)

 * @dev: the device

 *

 * This function is called by an iommu driver to add a device into a

 * group.  Adding a device increments the group reference count.

 */

int iommu_group_add_device(struct iommu_group *group, struct device *dev)

/* This is undone by __iommu_group_free_device() */

static struct group_device *iommu_group_alloc_device(struct iommu_group *group,

						     struct device *dev)

{

	int ret, i = 0;

	struct group_device *device;



	device = kzalloc(sizeof(*device), GFP_KERNEL);

	if (!device)

		return -ENOMEM;

		return ERR_PTR(-ENOMEM);



	device->dev = dev;
@@ -1113,17 +1114,11 @@ int iommu_group_add_device(struct iommu_group *group, struct device *dev) 
		goto err_free_name;

	}



	iommu_group_ref_get(group);

	dev->iommu_group = group;



	mutex_lock(&group->mutex);

	list_add_tail(&device->list, &group->devices);

	mutex_unlock(&group->mutex);

	trace_add_device_to_group(group->id, dev);



	dev_info(dev, "Adding to iommu group %d\n", group->id);



	return 0;

	return device;



err_free_name:

	kfree(device->name);
@@ -1132,7 +1127,32 @@ int iommu_group_add_device(struct iommu_group *group, struct device *dev) 
err_free_device:

	kfree(device);

	dev_err(dev, "Failed to add to iommu group %d: %d\n", group->id, ret);

	return ret;

	return ERR_PTR(ret);

}



/**

 * iommu_group_add_device - add a device to an iommu group

 * @group: the group into which to add the device (reference should be held)

 * @dev: the device

 *

 * This function is called by an iommu driver to add a device into a

 * group.  Adding a device increments the group reference count.

 */

int iommu_group_add_device(struct iommu_group *group, struct device *dev)

{

	struct group_device *gdev;



	gdev = iommu_group_alloc_device(group, dev);

	if (IS_ERR(gdev))

		return PTR_ERR(gdev);



	iommu_group_ref_get(group);

	dev->iommu_group = group;



	mutex_lock(&group->mutex);

	list_add_tail(&gdev->list, &group->devices);

	mutex_unlock(&group->mutex);

	return 0;

}

EXPORT_SYMBOL_GPL(iommu_group_add_device);