On Apr 18 2024, Alexei Starovoitov wrote: > On Tue, Apr 16, 2024 at 04:08:30PM +0200, Benjamin Tissoires wrote: > > again, copy/paste from bpf_timer_start(). > > > > Signed-off-by: Benjamin Tissoires <[email protected]> > > --- > > kernel/bpf/helpers.c | 24 ++++++++++++++++++++++++ > > 1 file changed, 24 insertions(+) > > > > diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c > > index e5c8adc44619..ed5309a37eda 100644 > > --- a/kernel/bpf/helpers.c > > +++ b/kernel/bpf/helpers.c > > @@ -2728,6 +2728,29 @@ __bpf_kfunc int bpf_wq_init(struct bpf_wq *wq, void > > *map, unsigned int flags) > > return __bpf_async_init(async, map, flags, BPF_ASYNC_TYPE_WQ); > > } > > > > +__bpf_kfunc int bpf_wq_start(struct bpf_wq *wq, unsigned int flags) > > +{ > > + struct bpf_async_kern *async = (struct bpf_async_kern *)wq; > > + struct bpf_work *w; > > + int ret = 0; > > + > > + if (in_nmi()) > > + return -EOPNOTSUPP; > > + if (flags) > > + return -EINVAL; > > + __bpf_spin_lock_irqsave(&async->lock); > > + w = async->work; > > + if (!w || !w->cb.prog) { > > + ret = -EINVAL; > > + goto out; > > + } > > + > > + schedule_work(&w->work); > > +out: > > + __bpf_spin_unlock_irqrestore(&async->lock); > > Looks like you're not adding wq_cancel kfunc in this patch set and > it's probably a good thing not to expose async cancel to bpf users, > since it's a foot gun.
Honestly I just felt the patch series was big enough for a PoC and comparison with sleepable bpf_timer. But if we think this needs not to be added, I guess that works too :) > Even when we eventually add wq_cancel_sync kfunc it will not be > removing a callback. Yeah, I understood that bit :) > So we can drop spinlock here. > READ_ONCE of w and cb would be enough. > Since they cannot get back to NULL once init-ed and cb is set. Great, thanks for the review (and the other patches). I'll work toward v2. Cheers, Benjamin
