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iommu: Split iommu_group_add_device()

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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: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/9-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 21:59:47 -03:00 committed by Joerg Roedel
parent cfb6ee65f7
commit fa08280364
1 changed files with 43 additions and 23 deletions
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66
drivers/iommu/iommu.c
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@ -129,6 +129,8 @@ static int iommu_create_device_direct_mappings(struct iommu_domain *domain,
struct device *dev); struct device *dev);
static ssize_t iommu_group_store_type(struct iommu_group *group, static ssize_t iommu_group_store_type(struct iommu_group *group,
const char *buf, size_t count); 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) \ #define IOMMU_GROUP_ATTR(_name, _mode, _show, _store) \
struct iommu_group_attribute iommu_group_attr_##_name = \ 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; const struct iommu_ops *ops = dev->bus->iommu_ops;
struct iommu_group *group; struct iommu_group *group;
static DEFINE_MUTEX(iommu_probe_device_lock); static DEFINE_MUTEX(iommu_probe_device_lock);
struct group_device *gdev;
int ret; int ret;
if (!ops) if (!ops)
@ -459,16 +462,17 @@ static int __iommu_probe_device(struct device *dev, struct list_head *group_list
goto out_unlock; goto out_unlock;
group = dev->iommu_group; group = dev->iommu_group;
ret = iommu_group_add_device(group, dev); gdev = iommu_group_alloc_device(group, dev);
mutex_lock(&group->mutex); mutex_lock(&group->mutex);
if (ret) if (IS_ERR(gdev)) {
ret = PTR_ERR(gdev);
goto err_put_group; goto err_put_group;
}
list_add_tail(&gdev->list, &group->devices);
if (group_list && !group->default_domain && list_empty(&group->entry)) if (group_list && !group->default_domain && list_empty(&group->entry))
list_add_tail(&group->entry, group_list); list_add_tail(&group->entry, group_list);
mutex_unlock(&group->mutex); mutex_unlock(&group->mutex);
iommu_group_put(group);
mutex_unlock(&iommu_probe_device_lock); mutex_unlock(&iommu_probe_device_lock);
return 0; return 0;
@ -578,7 +582,10 @@ static void __iommu_group_remove_device(struct device *dev)
} }
mutex_unlock(&group->mutex); 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); iommu_group_put(group);
} }
@ -1067,22 +1074,16 @@ out:
return ret; return ret;
} }
/** /* This is undone by __iommu_group_free_device() */
* iommu_group_add_device - add a device to an iommu group static struct group_device *iommu_group_alloc_device(struct iommu_group *group,
* @group: the group into which to add the device (reference should be held) struct device *dev)
* @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)
{ {
int ret, i = 0; int ret, i = 0;
struct group_device *device; struct group_device *device;
device = kzalloc(sizeof(*device), GFP_KERNEL); device = kzalloc(sizeof(*device), GFP_KERNEL);
if (!device) if (!device)
return -ENOMEM; return ERR_PTR(-ENOMEM);
device->dev = dev; device->dev = dev;
@ -1113,17 +1114,11 @@ rename:
goto err_free_name; 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); trace_add_device_to_group(group->id, dev);
dev_info(dev, "Adding to iommu group %d\n", group->id); dev_info(dev, "Adding to iommu group %d\n", group->id);
return 0; return device;
err_free_name: err_free_name:
kfree(device->name); kfree(device->name);
@ -1132,7 +1127,32 @@ err_remove_link:
err_free_device: err_free_device:
kfree(device); kfree(device);
dev_err(dev, "Failed to add to iommu group %d: %d\n", group->id, ret); 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); EXPORT_SYMBOL_GPL(iommu_group_add_device);