On Thu, May 19, 2022 at 5:45 PM Yonghong Song [off-list ref] wrote:

On 5/18/22 3:55 PM, Stanislav Fomichev wrote:

quoted

I'll be adding lsm cgroup specific helpers that grab
trampoline mutex.

No functional changes.

Signed-off-by: Stanislav Fomichev <redacted>
---
  include/linux/bpf.h     | 11 ++++----
  kernel/bpf/trampoline.c | 62 ++++++++++++++++++++++-------------------
  2 files changed, 38 insertions(+), 35 deletions(-)

[...]

quoted

+
+int bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr)
+{
+     int err;
+
+     mutex_lock(&tr->mutex);
+     err = __bpf_trampoline_link_prog(link, tr);
      mutex_unlock(&tr->mutex);
      return err;
  }

  /* bpf_trampoline_unlink_prog() should never fail. */

The comment here can be removed.

Will do, thank you!

quoted

-int bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr)
+static int __bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr)
  {
      enum bpf_tramp_prog_type kind;
      int err;

      kind = bpf_attach_type_to_tramp(link->link.prog);
-     mutex_lock(&tr->mutex);
      if (kind == BPF_TRAMP_REPLACE) {
              WARN_ON_ONCE(!tr->extension_prog);
              err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP,
                                       tr->extension_prog->bpf_func, NULL);
              tr->extension_prog = NULL;
-             goto out;
+             return err;
      }
      hlist_del_init(&link->tramp_hlist);
      tr->progs_cnt[kind]--;
-     err = bpf_trampoline_update(tr);
-out:
+     return bpf_trampoline_update(tr);
+}
+
+/* bpf_trampoline_unlink_prog() should never fail. */
+int bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr)
+{
+     int err;
+
+     mutex_lock(&tr->mutex);
+     err = __bpf_trampoline_unlink_prog(link, tr);
      mutex_unlock(&tr->mutex);
      return err;
  }