[PATCH bpf-next v2 03/11] bpf: Append complete reference states

[Ihor Solodrai]

Reference acquisition exposes an uninitialized entry for each caller to
fill after insertion.

Accept a complete reference entry and return its id after insertion. Keep
lock and IRQ accounting and acquisition diagnostics in their callers.
Take the target state directly so acquisition can also serve queued
callback states.

No functional change.

Signed-off-by: Ihor Solodrai <ihor.solodrai@xxxxxxxxx>
---
 kernel/bpf/verifier.c | 73 +++++++++++++++++++++++--------------------
 1 file changed, 39 insertions(+), 34 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 8d6812fee0c9..62b991f3c39a 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1497,51 +1497,53 @@ static int grow_stack_arg_slots(struct bpf_verifier_env *env,
 	return 0;
 }
 
-/* Acquire a pointer id from the env and update the state->refs to include
- * this new pointer reference.
- * On success, returns a valid pointer id to associate with the register
- * On failure, returns a negative errno.
+/*
+ * Append @ref to @state->refs. Return its id, or a negative errno.
  */
-static struct bpf_reference_state *acquire_reference_state(struct bpf_verifier_env *env, int insn_idx)
+static int acquire_reference_state(struct bpf_verifier_state *state,
+				   const struct bpf_reference_state *ref)
 {
-	struct bpf_verifier_state *state = env->cur_state;
 	int new_ofs = state->acquired_refs;
 	int err;
 
 	err = resize_reference_state(state, state->acquired_refs + 1);
 	if (err)
-		return NULL;
-	state->refs[new_ofs].insn_idx = insn_idx;
-
-	return &state->refs[new_ofs];
+		return err;
+	state->refs[new_ofs] = *ref;
+	return ref->id;
 }
 
 static int acquire_reference(struct bpf_verifier_env *env, int insn_idx, int parent_id)
 {
-	struct bpf_reference_state *s;
+	struct bpf_reference_state ref = {
+		.type = REF_TYPE_PTR,
+		.id = ++env->id_gen,
+		.insn_idx = insn_idx,
+		.parent_id = parent_id,
+	};
+	int id;
 
-	s = acquire_reference_state(env, insn_idx);
-	if (!s)
-		return -ENOMEM;
-	s->type = REF_TYPE_PTR;
-	s->id = ++env->id_gen;
-	s->parent_id = parent_id;
-	bpf_diag_record_ref_acquire(env, insn_idx, s->id);
-	return s->id;
+	id = acquire_reference_state(env->cur_state, &ref);
+	if (id >= 0)
+		bpf_diag_record_ref_acquire(env, insn_idx, id);
+	return id;
 }
 
 static int acquire_lock_state(struct bpf_verifier_env *env, int insn_idx, enum ref_state_type type,
 			      int id, void *ptr)
 {
 	struct bpf_verifier_state *state = env->cur_state;
-	struct bpf_reference_state *s;
+	struct bpf_reference_state ref = {
+		.type = type,
+		.id = id,
+		.insn_idx = insn_idx,
+		.ptr = ptr,
+	};
+	int err;
 
-	s = acquire_reference_state(env, insn_idx);
-	if (!s)
-		return -ENOMEM;
-	s->type = type;
-	s->id = id;
-	s->ptr = ptr;
+	err = acquire_reference_state(state, &ref);
+	if (err < 0)
+		return err;
 
 	state->active_locks++;
 	state->active_lock_id = id;
@@ -1554,18 +1556,21 @@ static int acquire_lock_state(struct bpf_verifier_env *env, int insn_idx, enum r
 static int acquire_irq_state(struct bpf_verifier_env *env, int insn_idx)
 {
 	struct bpf_verifier_state *state = env->cur_state;
-	struct bpf_reference_state *s;
+	struct bpf_reference_state ref = {
+		.type = REF_TYPE_IRQ,
+		.id = ++env->id_gen,
+		.insn_idx = insn_idx,
+	};
+	int id;
 
-	s = acquire_reference_state(env, insn_idx);
-	if (!s)
-		return -ENOMEM;
-	s->type = REF_TYPE_IRQ;
-	s->id = ++env->id_gen;
+	id = acquire_reference_state(state, &ref);
+	if (id < 0)
+		return id;
 
-	state->active_irq_id = s->id;
+	state->active_irq_id = id;
 	bpf_diag_record_context(env, insn_idx, BPF_DIAG_CONTEXT_IRQ, true,
 				bpf_diag_irq_depth(state));
-	return s->id;
+	return id;
 }
 
 static void release_reference_state(struct bpf_verifier_state *state, int idx)
-- 
2.56.0