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@kernel.org>
Link: https://lore.kernel.org/r/20240420-bpf_wq-v2-3-6c986a5a741f@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 0f02011715767c53dd968316b5e77ca2d9a1161e..1cbbf28e9398bb5b091e46b02f811ceed823aaee 100644 (file)
--- 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,