This is a note to let you know that I've just added the patch titled
bpf: make timer data struct more generic
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bpf-make-timer-data-struct-more-generic.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 50b0653229f7264cc76f243afa5f151ad7128850
Author: Benjamin Tissoires <bentiss@xxxxxxxxxx>
Date: Sat Apr 20 11:09:01 2024 +0200
bpf: make timer data struct more generic
[ 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@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240420-bpf_wq-v2-1-6c986a5a741f@xxxxxxxxxx
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Stable-dep-of: d4523831f07a ("bpf: Fail bpf_timer_cancel when callback is being cancelled")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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)
