RDMA/uverbs: Export XRC domains to user space

Allow user space to create XRC domains.  Because XRCDs are expected to
be shared among multiple processes, we use inodes to identify an XRCD.

Based on patches by Jack Morgenstein <jackm@dev.mellanox.co.il>

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

1 files changed, 318 insertions, 0 deletions

diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
index 48d21d09afe7..c8b2a843fa00 100644
--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -47,6 +47,7 @@ static struct lock_class_key cq_lock_key;
 static struct lock_class_key qp_lock_key;
 static struct lock_class_key ah_lock_key;
 static struct lock_class_key srq_lock_key;
+static struct lock_class_key xrcd_lock_key;
 
 #define INIT_UDATA(udata, ibuf, obuf, ilen, olen)			\
 	do {								\
@@ -255,6 +256,18 @@ static void put_srq_read(struct ib_srq *srq)
 	put_uobj_read(srq->uobject);
 }
 
+static struct ib_xrcd *idr_read_xrcd(int xrcd_handle, struct ib_ucontext *context,
+				     struct ib_uobject **uobj)
+{
+	*uobj = idr_read_uobj(&ib_uverbs_xrcd_idr, xrcd_handle, context, 0);
+	return *uobj ? (*uobj)->object : NULL;
+}
+
+static void put_xrcd_read(struct ib_uobject *uobj)
+{
+	put_uobj_read(uobj);
+}
+
 ssize_t ib_uverbs_get_context(struct ib_uverbs_file *file,
 			      const char __user *buf,
 			      int in_len, int out_len)
@@ -298,6 +311,7 @@ ssize_t ib_uverbs_get_context(struct ib_uverbs_file *file,
 	INIT_LIST_HEAD(&ucontext->qp_list);
 	INIT_LIST_HEAD(&ucontext->srq_list);
 	INIT_LIST_HEAD(&ucontext->ah_list);
+	INIT_LIST_HEAD(&ucontext->xrcd_list);
 	ucontext->closing = 0;
 
 	resp.num_comp_vectors = file->device->num_comp_vectors;
@@ -579,6 +593,310 @@ ssize_t ib_uverbs_dealloc_pd(struct ib_uverbs_file *file,
 	return in_len;
 }
 
+struct xrcd_table_entry {
+	struct rb_node  node;
+	struct ib_xrcd *xrcd;
+	struct inode   *inode;
+};
+
+static int xrcd_table_insert(struct ib_uverbs_device *dev,
+			    struct inode *inode,
+			    struct ib_xrcd *xrcd)
+{
+	struct xrcd_table_entry *entry, *scan;
+	struct rb_node **p = &dev->xrcd_tree.rb_node;
+	struct rb_node *parent = NULL;
+
+	entry = kmalloc(sizeof *entry, GFP_KERNEL);
+	if (!entry)
+		return -ENOMEM;
+
+	entry->xrcd  = xrcd;
+	entry->inode = inode;
+
+	while (*p) {
+		parent = *p;
+		scan = rb_entry(parent, struct xrcd_table_entry, node);
+
+		if (inode < scan->inode) {
+			p = &(*p)->rb_left;
+		} else if (inode > scan->inode) {
+			p = &(*p)->rb_right;
+		} else {
+			kfree(entry);
+			return -EEXIST;
+		}
+	}
+
+	rb_link_node(&entry->node, parent, p);
+	rb_insert_color(&entry->node, &dev->xrcd_tree);
+	igrab(inode);
+	return 0;
+}
+
+static struct xrcd_table_entry *xrcd_table_search(struct ib_uverbs_device *dev,
+						  struct inode *inode)
+{
+	struct xrcd_table_entry *entry;
+	struct rb_node *p = dev->xrcd_tree.rb_node;
+
+	while (p) {
+		entry = rb_entry(p, struct xrcd_table_entry, node);
+
+		if (inode < entry->inode)
+			p = p->rb_left;
+		else if (inode > entry->inode)
+			p = p->rb_right;
+		else
+			return entry;
+	}
+
+	return NULL;
+}
+
+static struct ib_xrcd *find_xrcd(struct ib_uverbs_device *dev, struct inode *inode)
+{
+	struct xrcd_table_entry *entry;
+
+	entry = xrcd_table_search(dev, inode);
+	if (!entry)
+		return NULL;
+
+	return entry->xrcd;
+}
+
+static void xrcd_table_delete(struct ib_uverbs_device *dev,
+			      struct inode *inode)
+{
+	struct xrcd_table_entry *entry;
+
+	entry = xrcd_table_search(dev, inode);
+	if (entry) {
+		iput(inode);
+		rb_erase(&entry->node, &dev->xrcd_tree);
+		kfree(entry);
+	}
+}
+
+ssize_t ib_uverbs_open_xrcd(struct ib_uverbs_file *file,
+			    const char __user *buf, int in_len,
+			    int out_len)
+{
+	struct ib_uverbs_open_xrcd	cmd;
+	struct ib_uverbs_open_xrcd_resp	resp;
+	struct ib_udata			udata;
+	struct ib_uxrcd_object         *obj;
+	struct ib_xrcd                 *xrcd = NULL;
+	struct file                    *f = NULL;
+	struct inode                   *inode = NULL;
+	int				ret = 0;
+	int				new_xrcd = 0;
+
+	if (out_len < sizeof resp)
+		return -ENOSPC;
+
+	if (copy_from_user(&cmd, buf, sizeof cmd))
+		return -EFAULT;
+
+	INIT_UDATA(&udata, buf + sizeof cmd,
+		   (unsigned long) cmd.response + sizeof resp,
+		   in_len - sizeof cmd, out_len - sizeof  resp);
+
+	mutex_lock(&file->device->xrcd_tree_mutex);
+
+	if (cmd.fd != -1) {
+		/* search for file descriptor */
+		f = fget(cmd.fd);
+		if (!f) {
+			ret = -EBADF;
+			goto err_tree_mutex_unlock;
+		}
+
+		inode = f->f_dentry->d_inode;
+		if (!inode) {
+			ret = -EBADF;
+			goto err_tree_mutex_unlock;
+		}
+
+		xrcd = find_xrcd(file->device, inode);
+		if (!xrcd && !(cmd.oflags & O_CREAT)) {
+			/* no file descriptor. Need CREATE flag */
+			ret = -EAGAIN;
+			goto err_tree_mutex_unlock;
+		}
+
+		if (xrcd && cmd.oflags & O_EXCL) {
+			ret = -EINVAL;
+			goto err_tree_mutex_unlock;
+		}
+	}
+
+	obj = kmalloc(sizeof *obj, GFP_KERNEL);
+	if (!obj) {
+		ret = -ENOMEM;
+		goto err_tree_mutex_unlock;
+	}
+
+	init_uobj(&obj->uobject, 0, file->ucontext, &xrcd_lock_key);
+
+	down_write(&obj->uobject.mutex);
+
+	if (!xrcd) {
+		xrcd = file->device->ib_dev->alloc_xrcd(file->device->ib_dev,
+							file->ucontext, &udata);
+		if (IS_ERR(xrcd)) {
+			ret = PTR_ERR(xrcd);
+			goto err;
+		}
+
+		xrcd->inode   = inode;
+		xrcd->device  = file->device->ib_dev;
+		atomic_set(&xrcd->usecnt, 0);
+		mutex_init(&xrcd->tgt_qp_mutex);
+		INIT_LIST_HEAD(&xrcd->tgt_qp_list);
+		new_xrcd = 1;
+	}
+
+	atomic_set(&obj->refcnt, 0);
+	obj->uobject.object = xrcd;
+	ret = idr_add_uobj(&ib_uverbs_xrcd_idr, &obj->uobject);
+	if (ret)
+		goto err_idr;
+
+	memset(&resp, 0, sizeof resp);
+	resp.xrcd_handle = obj->uobject.id;
+
+	if (inode) {
+		if (new_xrcd) {
+			/* create new inode/xrcd table entry */
+			ret = xrcd_table_insert(file->device, inode, xrcd);
+			if (ret)
+				goto err_insert_xrcd;
+		}
+		atomic_inc(&xrcd->usecnt);
+	}
+
+	if (copy_to_user((void __user *) (unsigned long) cmd.response,
+			 &resp, sizeof resp)) {
+		ret = -EFAULT;
+		goto err_copy;
+	}
+
+	if (f)
+		fput(f);
+
+	mutex_lock(&file->mutex);
+	list_add_tail(&obj->uobject.list, &file->ucontext->xrcd_list);
+	mutex_unlock(&file->mutex);
+
+	obj->uobject.live = 1;
+	up_write(&obj->uobject.mutex);
+
+	mutex_unlock(&file->device->xrcd_tree_mutex);
+	return in_len;
+
+err_copy:
+	if (inode) {
+		if (new_xrcd)
+			xrcd_table_delete(file->device, inode);
+		atomic_dec(&xrcd->usecnt);
+	}
+
+err_insert_xrcd:
+	idr_remove_uobj(&ib_uverbs_xrcd_idr, &obj->uobject);
+
+err_idr:
+	ib_dealloc_xrcd(xrcd);
+
+err:
+	put_uobj_write(&obj->uobject);
+
+err_tree_mutex_unlock:
+	if (f)
+		fput(f);
+
+	mutex_unlock(&file->device->xrcd_tree_mutex);
+
+	return ret;
+}
+
+ssize_t ib_uverbs_close_xrcd(struct ib_uverbs_file *file,
+			     const char __user *buf, int in_len,
+			     int out_len)
+{
+	struct ib_uverbs_close_xrcd cmd;
+	struct ib_uobject           *uobj;
+	struct ib_xrcd              *xrcd = NULL;
+	struct inode                *inode = NULL;
+	struct ib_uxrcd_object      *obj;
+	int                         live;
+	int                         ret = 0;
+
+	if (copy_from_user(&cmd, buf, sizeof cmd))
+		return -EFAULT;
+
+	mutex_lock(&file->device->xrcd_tree_mutex);
+	uobj = idr_write_uobj(&ib_uverbs_xrcd_idr, cmd.xrcd_handle, file->ucontext);
+	if (!uobj) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	xrcd  = uobj->object;
+	inode = xrcd->inode;
+	obj   = container_of(uobj, struct ib_uxrcd_object, uobject);
+	if (atomic_read(&obj->refcnt)) {
+		put_uobj_write(uobj);
+		ret = -EBUSY;
+		goto out;
+	}
+
+	if (!inode || atomic_dec_and_test(&xrcd->usecnt)) {
+		ret = ib_dealloc_xrcd(uobj->object);
+		if (!ret)
+			uobj->live = 0;
+	}
+
+	live = uobj->live;
+	if (inode && ret)
+		atomic_inc(&xrcd->usecnt);
+
+	put_uobj_write(uobj);
+
+	if (ret)
+		goto out;
+
+	if (inode && !live)
+		xrcd_table_delete(file->device, inode);
+
+	idr_remove_uobj(&ib_uverbs_xrcd_idr, uobj);
+	mutex_lock(&file->mutex);
+	list_del(&uobj->list);
+	mutex_unlock(&file->mutex);
+
+	put_uobj(uobj);
+	ret = in_len;
+
+out:
+	mutex_unlock(&file->device->xrcd_tree_mutex);
+	return ret;
+}
+
+void ib_uverbs_dealloc_xrcd(struct ib_uverbs_device *dev,
+			    struct ib_xrcd *xrcd)
+{
+	struct inode *inode;
+
+	inode = xrcd->inode;
+	if (inode && !atomic_dec_and_test(&xrcd->usecnt))
+		return;
+
+	ib_dealloc_xrcd(xrcd);
+
+	if (inode)
+		xrcd_table_delete(dev, inode);
+}
+
 ssize_t ib_uverbs_reg_mr(struct ib_uverbs_file *file,
 			 const char __user *buf, int in_len,
 			 int out_len)