[PATCH bpf-next 04/18] bpf: replace bpf_timer_set_callback with a generic helper

From: Benjamin Tissoires
Date: Tue Apr 16 2024 - 10:11:28 EST


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@xxxxxxxxxx>
---
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