netdev - [PATCH bpf-next v4 14/27] bpf: Change bpf_trampoline

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Date:   Thu, 26 Aug 2021 21:39:09 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andriin@...com>,
        "Steven Rostedt (VMware)" <rostedt@...dmis.org>
Cc:     netdev@...r.kernel.org, bpf@...r.kernel.org,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>, Daniel Xu <dxu@...uu.xyz>,
        Viktor Malik <vmalik@...hat.com>
Subject: [PATCH bpf-next v4 14/27] bpf: Change bpf_trampoline_get to return error pointer

Changing bpf_trampoline_get to return error pointer,
so we can return other than ENOMEM error in following
changes.

Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
 kernel/bpf/syscall.c    | 4 ++--
 kernel/bpf/trampoline.c | 8 +++++---
 kernel/bpf/verifier.c   | 4 ++--
 3 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index e667d392cc33..537687664bdf 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2793,8 +2793,8 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog,
 			goto out_unlock;
 
 		tr = bpf_trampoline_get(key, &tgt_info);
-		if (!tr) {
-			err = -ENOMEM;
+		if (IS_ERR(tr)) {
+			err = PTR_ERR(tr);
 			goto out_unlock;
 		}
 	} else {
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 8aa0aca38b3a..c9794e9f24ee 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -97,8 +97,10 @@ static struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
 		goto out;
 	}
 	tr = kzalloc(sizeof(*tr), GFP_KERNEL);
-	if (!tr)
+	if (!tr) {
+		tr = ERR_PTR(-ENOMEM);
 		goto out;
+	}
 	bpf_trampoline_init(tr, key);
 	head = &trampoline_table[hash_64(key, TRAMPOLINE_HASH_BITS)];
 	hlist_add_head(&tr->hlist, head);
@@ -508,8 +510,8 @@ struct bpf_trampoline *bpf_trampoline_get(u64 key,
 	struct bpf_trampoline *tr;
 
 	tr = bpf_trampoline_lookup(key);
-	if (!tr)
-		return NULL;
+	if (IS_ERR(tr))
+		return tr;
 
 	mutex_lock(&tr->mutex);
 	if (tr->func.addr)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index e9e84adfb974..ad410e1222e4 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -13642,8 +13642,8 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
 
 	key = bpf_trampoline_compute_key(tgt_prog, prog->aux->attach_btf, btf_id);
 	tr = bpf_trampoline_get(key, &tgt_info);
-	if (!tr)
-		return -ENOMEM;
+	if (IS_ERR(tr))
+		return PTR_ERR(tr);
 
 	prog->aux->dst_trampoline = tr;
 	return 0;
-- 
2.31.1