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authorKui-Feng Lee <[email protected]>2023-03-22 20:24:02 -0700
committerMartin KaFai Lau <[email protected]>2023-03-22 22:53:02 -0700
commitaef56f2e918bf8fc8de25f0b36e8c2aba44116ec (patch)
tree38d252f9d4fa8ef28ccf18e642bb3741d658fb92 /kernel/bpf/syscall.c
parent8d1608d70927747da9c1a8770edf7b6ee68f8ebc (diff)
bpf: Update the struct_ops of a bpf_link.
By improving the BPF_LINK_UPDATE command of bpf(), it should allow you to conveniently switch between different struct_ops on a single bpf_link. This would enable smoother transitions from one struct_ops to another. The struct_ops maps passing along with BPF_LINK_UPDATE should have the BPF_F_LINK flag. Signed-off-by: Kui-Feng Lee <[email protected]> Acked-by: Andrii Nakryiko <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Martin KaFai Lau <[email protected]>
Diffstat (limited to 'kernel/bpf/syscall.c')
-rw-r--r--kernel/bpf/syscall.c34
1 files changed, 34 insertions, 0 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 21f76698875c..b4d758fa5981 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -4682,6 +4682,35 @@ out:
return ret;
}
+static int link_update_map(struct bpf_link *link, union bpf_attr *attr)
+{
+ struct bpf_map *new_map, *old_map = NULL;
+ int ret;
+
+ new_map = bpf_map_get(attr->link_update.new_map_fd);
+ if (IS_ERR(new_map))
+ return -EINVAL;
+
+ if (attr->link_update.flags & BPF_F_REPLACE) {
+ old_map = bpf_map_get(attr->link_update.old_map_fd);
+ if (IS_ERR(old_map)) {
+ ret = -EINVAL;
+ goto out_put;
+ }
+ } else if (attr->link_update.old_map_fd) {
+ ret = -EINVAL;
+ goto out_put;
+ }
+
+ ret = link->ops->update_map(link, new_map, old_map);
+
+ if (old_map)
+ bpf_map_put(old_map);
+out_put:
+ bpf_map_put(new_map);
+ return ret;
+}
+
#define BPF_LINK_UPDATE_LAST_FIELD link_update.old_prog_fd
static int link_update(union bpf_attr *attr)
@@ -4702,6 +4731,11 @@ static int link_update(union bpf_attr *attr)
if (IS_ERR(link))
return PTR_ERR(link);
+ if (link->ops->update_map) {
+ ret = link_update_map(link, attr);
+ goto out_put_link;
+ }
+
new_prog = bpf_prog_get(attr->link_update.new_prog_fd);
if (IS_ERR(new_prog)) {
ret = PTR_ERR(new_prog);