From fa08280364882c42993dc5d8394c467d76803fdb Mon Sep 17 00:00:00 2001 From: Jason Gunthorpe Date: Mon, 5 Jun 2023 21:59:47 -0300 Subject: [PATCH] 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: Lu Baolu Reviewed-by: Kevin Tian Signed-off-by: Jason Gunthorpe Link: https://lore.kernel.org/r/9-v3-328044aa278c+45e49-iommu_probe_jgg@nvidia.com Signed-off-by: Joerg Roedel --- drivers/iommu/iommu.c | 66 +++++++++++++++++++++++++++++++++------------------ 1 file changed, 43 insertions(+), 23 deletions(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 55b916e..3129e5c 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -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 @@ out: 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 @@ rename: 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 @@ err_remove_link: 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); -- 2.7.4