[PATCH bpf-next v8 0/8] bpf: Extend the bpf_list family of APIs

[Chengkaitao]

From: Kaitao Cheng <chengkaitao@xxxxxxxxxx>

In BPF, a list can only be used to implement a stack structure.
Due to an incomplete API set, only FIFO or LIFO operations are
supported. The patches enhance the BPF list API, making it more
list-like.

Five new kfuncs have been added:
bpf_list_del: remove a node from the list
bpf_list_add_impl: insert a node after a given list node
bpf_list_is_first: check if a node is the first in the list
bpf_list_is_last: check if a node is the last in the list
bpf_list_empty: check if the list is empty

refactor kfunc checks to table-driven approach, and add test cases for
the aforementioned kfuncs.

Changes in v8:
- Use [patch v7 5/5] as the start of the patch series
- Introduce double pointer prev_ptr in __bpf_list_del
- Extract refactored __bpf_list_del/add into separate patches
- Allow bpf_list_front/back result as the prev argument of bpf_list_add
- Split test cases

Changes in v7:
- Replace bpf_list_node_is_edge with bpf_list_is_first/is_last
- Reimplement __bpf_list_del and __bpf_list_add
- Simplify test cases

Changes in v6:
- Merge [patch v5 (2,4,6)/6] into [patch v6 4/5]
- If list_head was 0-initialized, init it
- refactor kfunc checks to table-driven approach

Changes in v5:
- Fix bpf_obj leak on bpf_list_add_impl error

Changes in v4:
- [patch v3 1/6] Revert to version v1
- Change the parameters of bpf_list_add_impl to (head, new, prev, ...)

Changes in v3:
- Add a new lock_rec member to struct bpf_reference_state for lock
  holding detection.
- Add test cases to verify that the verifier correctly restricts calls
  to bpf_list_del when the spin_lock is not held.

Changes in v2:
- Remove the head parameter from bpf_list_del
- Add bpf_list_add/is_first/is_last/empty to API and test cases

Link to v7:
https://lore.kernel.org/all/20260308134614.29711-1-pilgrimtao@xxxxxxxxx/

Link to v6:
https://lore.kernel.org/all/20260304143459.78059-1-pilgrimtao@xxxxxxxxx/

Link to v5:
https://lore.kernel.org/all/20260304031606.43884-1-pilgrimtao@xxxxxxxxx/

Link to v4:
https://lore.kernel.org/all/20260303135219.33726-1-pilgrimtao@xxxxxxxxx/

Link to v3:
https://lore.kernel.org/all/20260302124028.82420-1-pilgrimtao@xxxxxxxxx/

Link to v2:
https://lore.kernel.org/all/20260225092651.94689-1-pilgrimtao@xxxxxxxxx/

Link to v1:
https://lore.kernel.org/all/20260209025250.55750-1-pilgrimtao@xxxxxxxxx/

Kaitao Cheng (8):
  bpf: refactor kfunc checks using table-driven approach in verifier
  bpf: refactor __bpf_list_del to take list node pointer
  bpf: Introduce the bpf_list_del kfunc.
  bpf: refactor __bpf_list_add to take insertion point via **prev_ptr
  bpf: Add bpf_list_add_impl to insert node after a given list node
  bpf: allow bpf_list_front/back result as the prev argument of
    bpf_list_add_impl
  bpf: add bpf_list_is_first/last/empty kfuncs
  selftests/bpf: Add test cases for
    bpf_list_del/add/is_first/is_last/empty

 kernel/bpf/helpers.c                          | 121 +++++--
 kernel/bpf/verifier.c                         | 116 +++++--
 .../testing/selftests/bpf/bpf_experimental.h  |  16 +
 .../selftests/bpf/progs/refcounted_kptr.c     | 311 ++++++++++++++++++
 4 files changed, 519 insertions(+), 45 deletions(-)

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