6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Benjamin Tissoires bentiss@kernel.org
[ Upstream commit be2749beff62e0d63cf97fe63cabc79a68443139 ]
To be able to add workqueues and reuse most of the timer code, we need to make bpf_hrtimer more generic.
There is no code change except that the new struct gets a new u64 flags attribute. We are still below 2 cache lines, so this shouldn't impact the current running codes.
The ordering is also changed. Everything related to async callback is now on top of bpf_hrtimer.
Signed-off-by: Benjamin Tissoires bentiss@kernel.org Link: https://lore.kernel.org/r/20240420-bpf_wq-v2-1-6c986a5a741f@kernel.org Signed-off-by: Alexei Starovoitov ast@kernel.org Stable-dep-of: d4523831f07a ("bpf: Fail bpf_timer_cancel when callback is being cancelled") Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/bpf/helpers.c | 71 ++++++++++++++++++++++++-------------------- 1 file changed, 38 insertions(+), 33 deletions(-)
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 31da67703307b..b7669e1236f70 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -1078,11 +1078,20 @@ const struct bpf_func_proto bpf_snprintf_proto = { .arg5_type = ARG_CONST_SIZE_OR_ZERO, };
+struct bpf_async_cb { + struct bpf_map *map; + struct bpf_prog *prog; + void __rcu *callback_fn; + void *value; + struct rcu_head rcu; + u64 flags; +}; + /* BPF map elements can contain 'struct bpf_timer'. * Such map owns all of its BPF timers. * 'struct bpf_timer' is allocated as part of map element allocation * and it's zero initialized. - * That space is used to keep 'struct bpf_timer_kern'. + * That space is used to keep 'struct bpf_async_kern'. * bpf_timer_init() allocates 'struct bpf_hrtimer', inits hrtimer, and * remembers 'struct bpf_map *' pointer it's part of. * bpf_timer_set_callback() increments prog refcnt and assign bpf callback_fn. @@ -1095,16 +1104,12 @@ const struct bpf_func_proto bpf_snprintf_proto = { * freeing the timers when inner map is replaced or deleted by user space. */ struct bpf_hrtimer { + struct bpf_async_cb cb; struct hrtimer timer; - struct bpf_map *map; - struct bpf_prog *prog; - void __rcu *callback_fn; - void *value; - struct rcu_head rcu; };
/* the actual struct hidden inside uapi struct bpf_timer */ -struct bpf_timer_kern { +struct bpf_async_kern { struct bpf_hrtimer *timer; /* bpf_spin_lock is used here instead of spinlock_t to make * sure that it always fits into space reserved by struct bpf_timer @@ -1118,14 +1123,14 @@ static DEFINE_PER_CPU(struct bpf_hrtimer *, hrtimer_running); static enum hrtimer_restart bpf_timer_cb(struct hrtimer *hrtimer) { struct bpf_hrtimer *t = container_of(hrtimer, struct bpf_hrtimer, timer); - struct bpf_map *map = t->map; - void *value = t->value; + struct bpf_map *map = t->cb.map; + void *value = t->cb.value; bpf_callback_t callback_fn; void *key; u32 idx;
BTF_TYPE_EMIT(struct bpf_timer); - callback_fn = rcu_dereference_check(t->callback_fn, rcu_read_lock_bh_held()); + callback_fn = rcu_dereference_check(t->cb.callback_fn, rcu_read_lock_bh_held()); if (!callback_fn) goto out;
@@ -1154,7 +1159,7 @@ static enum hrtimer_restart bpf_timer_cb(struct hrtimer *hrtimer) return HRTIMER_NORESTART; }
-BPF_CALL_3(bpf_timer_init, struct bpf_timer_kern *, timer, struct bpf_map *, map, +BPF_CALL_3(bpf_timer_init, struct bpf_async_kern *, timer, struct bpf_map *, map, u64, flags) { clockid_t clockid = flags & (MAX_CLOCKS - 1); @@ -1162,8 +1167,8 @@ BPF_CALL_3(bpf_timer_init, struct bpf_timer_kern *, timer, struct bpf_map *, map int ret = 0;
BUILD_BUG_ON(MAX_CLOCKS != 16); - BUILD_BUG_ON(sizeof(struct bpf_timer_kern) > sizeof(struct bpf_timer)); - BUILD_BUG_ON(__alignof__(struct bpf_timer_kern) != __alignof__(struct bpf_timer)); + BUILD_BUG_ON(sizeof(struct bpf_async_kern) > sizeof(struct bpf_timer)); + BUILD_BUG_ON(__alignof__(struct bpf_async_kern) != __alignof__(struct bpf_timer));
if (in_nmi()) return -EOPNOTSUPP; @@ -1186,10 +1191,10 @@ BPF_CALL_3(bpf_timer_init, struct bpf_timer_kern *, timer, struct bpf_map *, map ret = -ENOMEM; goto out; } - t->value = (void *)timer - map->record->timer_off; - t->map = map; - t->prog = NULL; - rcu_assign_pointer(t->callback_fn, NULL); + t->cb.value = (void *)timer - map->record->timer_off; + t->cb.map = map; + t->cb.prog = NULL; + rcu_assign_pointer(t->cb.callback_fn, NULL); hrtimer_init(&t->timer, clockid, HRTIMER_MODE_REL_SOFT); t->timer.function = bpf_timer_cb; WRITE_ONCE(timer->timer, t); @@ -1221,7 +1226,7 @@ static const struct bpf_func_proto bpf_timer_init_proto = { .arg3_type = ARG_ANYTHING, };
-BPF_CALL_3(bpf_timer_set_callback, struct bpf_timer_kern *, timer, void *, callback_fn, +BPF_CALL_3(bpf_timer_set_callback, struct bpf_async_kern *, timer, void *, callback_fn, struct bpf_prog_aux *, aux) { struct bpf_prog *prev, *prog = aux->prog; @@ -1236,7 +1241,7 @@ BPF_CALL_3(bpf_timer_set_callback, struct bpf_timer_kern *, timer, void *, callb ret = -EINVAL; goto out; } - if (!atomic64_read(&t->map->usercnt)) { + if (!atomic64_read(&t->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 @@ -1245,7 +1250,7 @@ BPF_CALL_3(bpf_timer_set_callback, struct bpf_timer_kern *, timer, void *, callb ret = -EPERM; goto out; } - prev = t->prog; + prev = t->cb.prog; if (prev != prog) { /* Bump prog refcnt once. Every bpf_timer_set_callback() * can pick different callback_fn-s within the same prog. @@ -1258,9 +1263,9 @@ BPF_CALL_3(bpf_timer_set_callback, struct bpf_timer_kern *, timer, void *, callb if (prev) /* Drop prev prog refcnt when swapping with new prog */ bpf_prog_put(prev); - t->prog = prog; + t->cb.prog = prog; } - rcu_assign_pointer(t->callback_fn, callback_fn); + rcu_assign_pointer(t->cb.callback_fn, callback_fn); out: __bpf_spin_unlock_irqrestore(&timer->lock); return ret; @@ -1274,7 +1279,7 @@ static const struct bpf_func_proto bpf_timer_set_callback_proto = { .arg2_type = ARG_PTR_TO_FUNC, };
-BPF_CALL_3(bpf_timer_start, struct bpf_timer_kern *, timer, u64, nsecs, u64, flags) +BPF_CALL_3(bpf_timer_start, struct bpf_async_kern *, timer, u64, nsecs, u64, flags) { struct bpf_hrtimer *t; int ret = 0; @@ -1286,7 +1291,7 @@ BPF_CALL_3(bpf_timer_start, struct bpf_timer_kern *, timer, u64, nsecs, u64, fla return -EINVAL; __bpf_spin_lock_irqsave(&timer->lock); t = timer->timer; - if (!t || !t->prog) { + if (!t || !t->cb.prog) { ret = -EINVAL; goto out; } @@ -1311,18 +1316,18 @@ static const struct bpf_func_proto bpf_timer_start_proto = { .arg3_type = ARG_ANYTHING, };
-static void drop_prog_refcnt(struct bpf_hrtimer *t) +static void drop_prog_refcnt(struct bpf_async_cb *async) { - struct bpf_prog *prog = t->prog; + struct bpf_prog *prog = async->prog;
if (prog) { bpf_prog_put(prog); - t->prog = NULL; - rcu_assign_pointer(t->callback_fn, NULL); + async->prog = NULL; + rcu_assign_pointer(async->callback_fn, NULL); } }
-BPF_CALL_1(bpf_timer_cancel, struct bpf_timer_kern *, timer) +BPF_CALL_1(bpf_timer_cancel, struct bpf_async_kern *, timer) { struct bpf_hrtimer *t; int ret = 0; @@ -1344,7 +1349,7 @@ BPF_CALL_1(bpf_timer_cancel, struct bpf_timer_kern *, timer) ret = -EDEADLK; goto out; } - drop_prog_refcnt(t); + drop_prog_refcnt(&t->cb); out: __bpf_spin_unlock_irqrestore(&timer->lock); /* Cancel the timer and wait for associated callback to finish @@ -1367,7 +1372,7 @@ static const struct bpf_func_proto bpf_timer_cancel_proto = { */ void bpf_timer_cancel_and_free(void *val) { - struct bpf_timer_kern *timer = val; + struct bpf_async_kern *timer = val; struct bpf_hrtimer *t;
/* Performance optimization: read timer->timer without lock first. */ @@ -1379,7 +1384,7 @@ void bpf_timer_cancel_and_free(void *val) t = timer->timer; if (!t) goto out; - drop_prog_refcnt(t); + drop_prog_refcnt(&t->cb); /* The subsequent bpf_timer_start/cancel() helpers won't be able to use * this timer, since it won't be initialized. */ @@ -1406,7 +1411,7 @@ void bpf_timer_cancel_and_free(void *val) */ if (this_cpu_read(hrtimer_running) != t) hrtimer_cancel(&t->timer); - kfree_rcu(t, rcu); + kfree_rcu(t, cb.rcu); }
BPF_CALL_2(bpf_kptr_xchg, void *, map_value, void *, ptr)