[RFC,bpf-next,1/3] bpf: Enable bpf_cgrp_storage for cgroup1 non-attach case

Commit Message

Yafang Shao Dec. 5, 2023, 2:37 p.m. UTC

In the current cgroup1 environment, associating operations between a cgroup
and applications in a BPF program requires storing a mapping of cgroup_id
to application either in a hash map or maintaining it in userspace.
However, by enabling bpf_cgrp_storage for cgroup1, it becomes possible to
conveniently store application-specific information in cgroup-local storage
and utilize it within BPF programs. Furthermore, enabling this feature for
cgroup1 involves minor modifications for the non-attach case, streamlining
the process.

However, when it comes to enabling this functionality for the cgroup1
attach case, it presents challenges. Therefore, the decision is to focus on
enabling it solely for the cgroup1 non-attach case at present. If
attempting to attach to a cgroup1 fd, the operation will simply fail with
the error code -EBADF.

Signed-off-by: Yafang Shao <[e-mail]>
---
 kernel/bpf/bpf_cgrp_storage.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Comments

Yonghong Song Dec. 6, 2023, 4:17 a.m. UTC | #1

On 12/5/23 9:37 AM, Yafang Shao wrote:
> In the current cgroup1 environment, associating operations between a cgroup
> and applications in a BPF program requires storing a mapping of cgroup_id
> to application either in a hash map or maintaining it in userspace.
> However, by enabling bpf_cgrp_storage for cgroup1, it becomes possible to
> conveniently store application-specific information in cgroup-local storage
> and utilize it within BPF programs. Furthermore, enabling this feature for
> cgroup1 involves minor modifications for the non-attach case, streamlining
> the process.
>
> However, when it comes to enabling this functionality for the cgroup1
> attach case, it presents challenges. Therefore, the decision is to focus on
> enabling it solely for the cgroup1 non-attach case at present. If
> attempting to attach to a cgroup1 fd, the operation will simply fail with
> the error code -EBADF.
>
> Signed-off-by: Yafang Shao <[e-mail]>

Acked-by: Yonghong Song <[e-mail]>

Patch

diff --git a/kernel/bpf/bpf_cgrp_storage.c b/kernel/bpf/bpf_cgrp_storage.c
index d44fe8dd9732..28efd0a3f220 100644
--- a/kernel/bpf/bpf_cgrp_storage.c
+++ b/kernel/bpf/bpf_cgrp_storage.c
@@ -82,7 +82,7 @@  static void *bpf_cgrp_storage_lookup_elem(struct bpf_map *map, void *key)
 	int fd;
 
 	fd = *(int *)key;
-	cgroup = cgroup_get_from_fd(fd);
+	cgroup = cgroup_v1v2_get_from_fd(fd);
 	if (IS_ERR(cgroup))
 		return ERR_CAST(cgroup);
 
@@ -101,7 +101,7 @@  static long bpf_cgrp_storage_update_elem(struct bpf_map *map, void *key,
 	int fd;
 
 	fd = *(int *)key;
-	cgroup = cgroup_get_from_fd(fd);
+	cgroup = cgroup_v1v2_get_from_fd(fd);
 	if (IS_ERR(cgroup))
 		return PTR_ERR(cgroup);
 
@@ -131,7 +131,7 @@  static long bpf_cgrp_storage_delete_elem(struct bpf_map *map, void *key)
 	int err, fd;
 
 	fd = *(int *)key;
-	cgroup = cgroup_get_from_fd(fd);
+	cgroup = cgroup_v1v2_get_from_fd(fd);
 	if (IS_ERR(cgroup))
 		return PTR_ERR(cgroup);