From: Chengchang Tang <tangchengchang@xxxxxxxxxx>
Provide a new api rdma_user_mmap_disassociate() for drivers to
disassociate mmap pages for a device.
Since drivers can now disassociate mmaps by calling this api,
introduce a new disassociation_lock to specifically prevent
races between this disassociation process and new mmaps. And
thus the old hw_destroy_rwsem is not needed in this api.
Signed-off-by: Chengchang Tang <tangchengchang@xxxxxxxxxx>
Signed-off-by: Junxian Huang <huangjunxian6@xxxxxxxxxxxxx>
---
drivers/infiniband/core/uverbs.h | 2 ++
drivers/infiniband/core/uverbs_main.c | 43 +++++++++++++++++++++++++--
include/rdma/ib_verbs.h | 8 +++++
3 files changed, 51 insertions(+), 2 deletions(-)
diff --git a/drivers/infiniband/core/uverbs.h b/drivers/infiniband/core/uverbs.h
index 821d93c8f712..dfd2e5a86e6f 100644
--- a/drivers/infiniband/core/uverbs.h
+++ b/drivers/infiniband/core/uverbs.h
@@ -160,6 +160,8 @@ struct ib_uverbs_file {
struct page *disassociate_page;
struct xarray idr;
+
+ struct mutex disassociation_lock;
};
struct ib_uverbs_event {
diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
index bc099287de9a..48b97e6c1fc6 100644
--- a/drivers/infiniband/core/uverbs_main.c
+++ b/drivers/infiniband/core/uverbs_main.c
@@ -76,6 +76,7 @@ static dev_t dynamic_uverbs_dev;
static DEFINE_IDA(uverbs_ida);
static int ib_uverbs_add_one(struct ib_device *device);
static void ib_uverbs_remove_one(struct ib_device *device, void *client_data);
+static struct ib_client uverbs_client;
static char *uverbs_devnode(const struct device *dev, umode_t *mode)
{
@@ -217,6 +218,7 @@ void ib_uverbs_release_file(struct kref *ref)
if (file->disassociate_page)
__free_pages(file->disassociate_page, 0);
+ mutex_destroy(&file->disassociation_lock);
mutex_destroy(&file->umap_lock);
mutex_destroy(&file->ucontext_lock);
kfree(file);
@@ -700,8 +702,13 @@ static int ib_uverbs_mmap(struct file *filp, struct vm_area_struct *vma)
ret = PTR_ERR(ucontext);
goto out;
}
+
+ mutex_lock(&file->disassociation_lock);
+
vma->vm_ops = &rdma_umap_ops;
ret = ucontext->device->ops.mmap(ucontext, vma);
+
+ mutex_unlock(&file->disassociation_lock);
out:
srcu_read_unlock(&file->device->disassociate_srcu, srcu_key);
return ret;
@@ -723,6 +730,8 @@ static void rdma_umap_open(struct vm_area_struct *vma)
/* We are racing with disassociation */
if (!down_read_trylock(&ufile->hw_destroy_rwsem))
goto out_zap;
+ mutex_lock(&ufile->disassociation_lock);
+
/*
* Disassociation already completed, the VMA should already be zapped.
*/
@@ -734,10 +743,12 @@ static void rdma_umap_open(struct vm_area_struct *vma)
goto out_unlock;
rdma_umap_priv_init(priv, vma, opriv->entry);
+ mutex_unlock(&ufile->disassociation_lock);
up_read(&ufile->hw_destroy_rwsem);
return;
out_unlock:
+ mutex_unlock(&ufile->disassociation_lock);
up_read(&ufile->hw_destroy_rwsem);
out_zap:
/*
@@ -821,7 +832,7 @@ void uverbs_user_mmap_disassociate(struct ib_uverbs_file *ufile)
{
struct rdma_umap_priv *priv, *next_priv;
- lockdep_assert_held(&ufile->hw_destroy_rwsem);
+ mutex_lock(&ufile->disassociation_lock);
while (1) {
struct mm_struct *mm = NULL;
@@ -847,8 +858,10 @@ void uverbs_user_mmap_disassociate(struct ib_uverbs_file *ufile)
break;
}
mutex_unlock(&ufile->umap_lock);
- if (!mm)
+ if (!mm) {
+ mutex_unlock(&ufile->disassociation_lock);
return;
+ }
/*
* The umap_lock is nested under mmap_lock since it used within
@@ -878,7 +891,31 @@ void uverbs_user_mmap_disassociate(struct ib_uverbs_file *ufile)
mmap_read_unlock(mm);
mmput(mm);
}
+
+ mutex_unlock(&ufile->disassociation_lock);
+}
+
+/**
+ * rdma_user_mmap_disassociate() - Revoke mmaps for a device
+ * @device: device to revoke
+ *
+ * This function should be called by drivers that need to disable mmaps for the
+ * device, for instance because it is going to be reset.
+ */
+void rdma_user_mmap_disassociate(struct ib_device *device)
+{
+ struct ib_uverbs_device *uverbs_dev =
+ ib_get_client_data(device, &uverbs_client);
+ struct ib_uverbs_file *ufile;
+
+ mutex_lock(&uverbs_dev->lists_mutex);
+ list_for_each_entry(ufile, &uverbs_dev->uverbs_file_list, list) {
+ if (ufile->ucontext)
+ uverbs_user_mmap_disassociate(ufile);
+ }
+ mutex_unlock(&uverbs_dev->lists_mutex);
}
+EXPORT_SYMBOL(rdma_user_mmap_disassociate);
/*
* ib_uverbs_open() does not need the BKL:
@@ -949,6 +986,8 @@ static int ib_uverbs_open(struct inode *inode, struct file *filp)
mutex_init(&file->umap_lock);
INIT_LIST_HEAD(&file->umaps);
+ mutex_init(&file->disassociation_lock);
+
filp->private_data = file;
list_add_tail(&file->list, &dev->uverbs_file_list);
mutex_unlock(&dev->lists_mutex);
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index aa8ede439905..9cb8b5fe7eee 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -2948,6 +2948,14 @@ int rdma_user_mmap_entry_insert_range(struct ib_ucontext *ucontext,
size_t length, u32 min_pgoff,
u32 max_pgoff);
+#if IS_ENABLED(CONFIG_INFINIBAND_USER_ACCESS)
+void rdma_user_mmap_disassociate(struct ib_device *device);
+#else
+static inline void rdma_user_mmap_disassociate(struct ib_device *device)
+{
+}
+#endif
+
static inline int
rdma_user_mmap_entry_insert_exact(struct ib_ucontext *ucontext,
struct rdma_user_mmap_entry *entry,
--
2.33.0
