[RFC PATCH bpf-next 1/2] net: bpf: Make xdp and cls_bpf use bpf_prog_put_dev()

[Daniel Xu]

This commit adds a stubbed bpf_prog_put_dev() that is symmetric to
bpf_prog_get_type_dev() such that all bpf device attachments are using a
*_dev() API.

This gives core bpf the ability to do special refcnt handling for device
attachments.

Signed-off-by: Daniel Xu <dxu@xxxxxxxxx>
---
 include/linux/bpf.h  |  1 +
 kernel/bpf/devmap.c  |  8 ++++----
 kernel/bpf/syscall.c |  6 ++++++
 net/core/dev.c       | 16 ++++++++--------
 net/sched/cls_bpf.c  |  4 ++--
 5 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index eced6400f778..08269ad8cc45 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2030,6 +2030,7 @@ void bpf_prog_sub(struct bpf_prog *prog, int i);
 void bpf_prog_inc(struct bpf_prog *prog);
 struct bpf_prog * __must_check bpf_prog_inc_not_zero(struct bpf_prog *prog);
 void bpf_prog_put(struct bpf_prog *prog);
+void bpf_prog_put_dev(struct bpf_prog *prog);
 
 void bpf_prog_free_id(struct bpf_prog *prog);
 void bpf_map_free_id(struct bpf_map *map);
diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index 4d42f6ed6c11..b5d33a87a560 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -212,7 +212,7 @@ static void dev_map_free(struct bpf_map *map)
 			hlist_for_each_entry_safe(dev, next, head, index_hlist) {
 				hlist_del_rcu(&dev->index_hlist);
 				if (dev->xdp_prog)
-					bpf_prog_put(dev->xdp_prog);
+					bpf_prog_put_dev(dev->xdp_prog);
 				dev_put(dev->dev);
 				kfree(dev);
 			}
@@ -228,7 +228,7 @@ static void dev_map_free(struct bpf_map *map)
 				continue;
 
 			if (dev->xdp_prog)
-				bpf_prog_put(dev->xdp_prog);
+				bpf_prog_put_dev(dev->xdp_prog);
 			dev_put(dev->dev);
 			kfree(dev);
 		}
@@ -800,7 +800,7 @@ static void __dev_map_entry_free(struct rcu_head *rcu)
 
 	dev = container_of(rcu, struct bpf_dtab_netdev, rcu);
 	if (dev->xdp_prog)
-		bpf_prog_put(dev->xdp_prog);
+		bpf_prog_put_dev(dev->xdp_prog);
 	dev_put(dev->dev);
 	kfree(dev);
 }
@@ -884,7 +884,7 @@ static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net,
 
 	return dev;
 err_put_prog:
-	bpf_prog_put(prog);
+	bpf_prog_put_dev(prog);
 err_put_dev:
 	dev_put(dev->dev);
 err_out:
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 10666d17b9e3..d8e5530598f3 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2164,6 +2164,12 @@ void bpf_prog_put(struct bpf_prog *prog)
 }
 EXPORT_SYMBOL_GPL(bpf_prog_put);
 
+void bpf_prog_put_dev(struct bpf_prog *prog)
+{
+	bpf_prog_put(prog);
+}
+EXPORT_SYMBOL_GPL(bpf_prog_put_dev);
+
 static int bpf_prog_release(struct inode *inode, struct file *filp)
 {
 	struct bpf_prog *prog = filp->private_data;
diff --git a/net/core/dev.c b/net/core/dev.c
index 17e6281e408c..ed0ece344416 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5676,7 +5676,7 @@ static int generic_xdp_install(struct net_device *dev, struct netdev_bpf *xdp)
 	case XDP_SETUP_PROG:
 		rcu_assign_pointer(dev->xdp_prog, new);
 		if (old)
-			bpf_prog_put(old);
+			bpf_prog_put_dev(old);
 
 		if (old && !new) {
 			static_branch_dec(&generic_xdp_needed_key);
@@ -9167,7 +9167,7 @@ static int dev_xdp_install(struct net_device *dev, enum bpf_xdp_mode mode,
 	err = bpf_op(dev, &xdp);
 	if (err) {
 		if (prog)
-			bpf_prog_put(prog);
+			bpf_prog_put_dev(prog);
 		return err;
 	}
 
@@ -9202,7 +9202,7 @@ static void dev_xdp_uninstall(struct net_device *dev)
 		if (link)
 			link->dev = NULL;
 		else
-			bpf_prog_put(prog);
+			bpf_prog_put_dev(prog);
 
 		dev_xdp_set_link(dev, mode, NULL);
 	}
@@ -9326,7 +9326,7 @@ static int dev_xdp_attach(struct net_device *dev, struct netlink_ext_ack *extack
 	else
 		dev_xdp_set_prog(dev, mode, new_prog);
 	if (cur_prog)
-		bpf_prog_put(cur_prog);
+		bpf_prog_put_dev(cur_prog);
 
 	return 0;
 }
@@ -9445,7 +9445,7 @@ static int bpf_xdp_link_update(struct bpf_link *link, struct bpf_prog *new_prog,
 
 	if (old_prog == new_prog) {
 		/* no-op, don't disturb drivers */
-		bpf_prog_put(new_prog);
+		bpf_prog_put_dev(new_prog);
 		goto out_unlock;
 	}
 
@@ -9457,7 +9457,7 @@ static int bpf_xdp_link_update(struct bpf_link *link, struct bpf_prog *new_prog,
 		goto out_unlock;
 
 	old_prog = xchg(&link->prog, new_prog);
-	bpf_prog_put(old_prog);
+	bpf_prog_put_dev(old_prog);
 
 out_unlock:
 	rtnl_unlock();
@@ -9568,9 +9568,9 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
 
 err_out:
 	if (err && new_prog)
-		bpf_prog_put(new_prog);
+		bpf_prog_put_dev(new_prog);
 	if (old_prog)
-		bpf_prog_put(old_prog);
+		bpf_prog_put_dev(old_prog);
 	return err;
 }
 
diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c
index 382c7a71f81f..20129d73dab4 100644
--- a/net/sched/cls_bpf.c
+++ b/net/sched/cls_bpf.c
@@ -258,7 +258,7 @@ static int cls_bpf_init(struct tcf_proto *tp)
 static void cls_bpf_free_parms(struct cls_bpf_prog *prog)
 {
 	if (cls_bpf_is_ebpf(prog))
-		bpf_prog_put(prog->filter);
+		bpf_prog_put_dev(prog->filter);
 	else
 		bpf_prog_destroy(prog->filter);
 
@@ -391,7 +391,7 @@ static int cls_bpf_prog_from_efd(struct nlattr **tb, struct cls_bpf_prog *prog,
 	if (tb[TCA_BPF_NAME]) {
 		name = nla_memdup(tb[TCA_BPF_NAME], GFP_KERNEL);
 		if (!name) {
-			bpf_prog_put(fp);
+			bpf_prog_put_dev(fp);
 			return -ENOMEM;
 		}
 	}
-- 
2.41.0