linux-kernel - [PATCH bpf-next 04/18] bpf: replace bpf_timer_set

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Date: Tue, 16 Apr 2024 16:08:17 +0200
From: Benjamin Tissoires <bentiss@...nel.org>
To: Alexei Starovoitov <ast@...nel.org>, 
 Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>, 
 Martin KaFai Lau <martin.lau@...ux.dev>, 
 Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>, 
 Yonghong Song <yonghong.song@...ux.dev>, 
 John Fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>, 
 Stanislav Fomichev <sdf@...gle.com>, Hao Luo <haoluo@...gle.com>, 
 Jiri Olsa <jolsa@...nel.org>, Mykola Lysenko <mykolal@...com>, 
 Shuah Khan <shuah@...nel.org>
Cc: bpf@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-kselftest@...r.kernel.org, Benjamin Tissoires <bentiss@...nel.org>
Subject: [PATCH bpf-next 04/18] bpf: replace bpf_timer_set_callback with a
 generic helper

In the same way we have a generic __bpf_async_init(), we also need
to share code between timer and workqueue for the set_callback call.

We just add an unused flags parameter, as it will be used for workqueues.

Signed-off-by: Benjamin Tissoires <bentiss@...nel.org>
---
 kernel/bpf/helpers.c | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 1e6d1011303b..d0a645b09d3d 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -1262,22 +1262,23 @@ static const struct bpf_func_proto bpf_timer_init_proto = {
 	.arg3_type	= ARG_ANYTHING,
 };
 
-BPF_CALL_3(bpf_timer_set_callback, struct bpf_async_kern *, timer, void *, callback_fn,
-	   struct bpf_prog_aux *, aux)
+static int __bpf_async_set_callback(struct bpf_async_kern *async, void *callback_fn,
+				    struct bpf_prog_aux *aux, unsigned int flags,
+				    enum bpf_async_type type)
 {
 	struct bpf_prog *prev, *prog = aux->prog;
-	struct bpf_hrtimer *t;
+	struct bpf_async_cb *cb;
 	int ret = 0;
 
 	if (in_nmi())
 		return -EOPNOTSUPP;
-	__bpf_spin_lock_irqsave(&timer->lock);
-	t = timer->timer;
-	if (!t) {
+	__bpf_spin_lock_irqsave(&async->lock);
+	cb = async->cb;
+	if (!cb) {
 		ret = -EINVAL;
 		goto out;
 	}
-	if (!atomic64_read(&t->cb.map->usercnt)) {
+	if (!atomic64_read(&cb->map->usercnt)) {
 		/* maps with timers must be either held by user space
 		 * or pinned in bpffs. Otherwise timer might still be
 		 * running even when bpf prog is detached and user space
@@ -1286,7 +1287,7 @@ BPF_CALL_3(bpf_timer_set_callback, struct bpf_async_kern *, timer, void *, callb
 		ret = -EPERM;
 		goto out;
 	}
-	prev = t->cb.prog;
+	prev = cb->prog;
 	if (prev != prog) {
 		/* Bump prog refcnt once. Every bpf_timer_set_callback()
 		 * can pick different callback_fn-s within the same prog.
@@ -1299,14 +1300,20 @@ BPF_CALL_3(bpf_timer_set_callback, struct bpf_async_kern *, timer, void *, callb
 		if (prev)
 			/* Drop prev prog refcnt when swapping with new prog */
 			bpf_prog_put(prev);
-		t->cb.prog = prog;
+		cb->prog = prog;
 	}
-	rcu_assign_pointer(t->cb.callback_fn, callback_fn);
+	rcu_assign_pointer(cb->callback_fn, callback_fn);
 out:
-	__bpf_spin_unlock_irqrestore(&timer->lock);
+	__bpf_spin_unlock_irqrestore(&async->lock);
 	return ret;
 }
 
+BPF_CALL_3(bpf_timer_set_callback, struct bpf_async_kern *, timer, void *, callback_fn,
+	   struct bpf_prog_aux *, aux)
+{
+	return __bpf_async_set_callback(timer, callback_fn, aux, 0, BPF_ASYNC_TYPE_TIMER);
+}
+
 static const struct bpf_func_proto bpf_timer_set_callback_proto = {
 	.func		= bpf_timer_set_callback,
 	.gpl_only	= true,

-- 
2.44.0