From: Christian Marangi <ansuelsmth@gmail•com>
To: Eric Dumazet <edumazet@google•com>
Cc: "Andrew Lunn" <andrew@lunn•ch>,
"Sergey Ryazanov" <ryazanov.s.a@gmail•com>,
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Subject: Re: [net-next PATCH v2 3/4] netdev: replace napi_reschedule with napi_schedule
Date: Fri, 6 Oct 2023 20:52:57 +0200 [thread overview]
Message-ID: <65205789.5d0a0220.7e49b.ccb0@mx.google.com> (raw)
In-Reply-To: <CANn89iJQ50AdXP2C1YB2pGjE02WCJ-QCsZqE1yGXtcGsfLA0Jw@mail.gmail.com>
On Thu, Oct 05, 2023 at 06:41:03PM +0200, Eric Dumazet wrote:
> On Thu, Oct 5, 2023 at 6:32 PM Jakub Kicinski <kuba@kernel•org> wrote:
> >
> > On Thu, 5 Oct 2023 18:11:56 +0200 Eric Dumazet wrote:
> > > OK, but I suspect some users of napi_reschedule() might not be race-free...
> >
> > What's the race you're thinking of?
>
> This sort of thing... the race is in fl_starving() though...
>
> diff --git a/drivers/net/ethernet/chelsio/cxgb4/sge.c
> b/drivers/net/ethernet/chelsio/cxgb4/sge.c
> index 98dd78551d89..b5ff2e1a9975 100644
> --- a/drivers/net/ethernet/chelsio/cxgb4/sge.c
> +++ b/drivers/net/ethernet/chelsio/cxgb4/sge.c
> @@ -4261,7 +4261,7 @@ static void sge_rx_timer_cb(struct timer_list *t)
>
> if (fl_starving(adap, fl)) {
> rxq = container_of(fl, struct sge_eth_rxq, fl);
> - if (napi_reschedule(&rxq->rspq.napi))
> + if (napi_schedule(&rxq->rspq.napi))
> fl->starving++;
> else
> set_bit(id, s->starving_fl);
Ehhh problem is that this is a simple rename so if any race is present,
it's already there and not caused by this rename :(
Don't know maybe this is out of scope and should be investigated with a
bug report?
Maybe this should be changed to prep/__schedule to prevent any kind of
race? But doing so doesn't prevent any kind of ""starving""?
--
Ansuel
next prev parent reply other threads:[~2023-10-07 23:38 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-03 14:51 [net-next PATCH v2 1/4] netdev: replace simple napi_schedule_prep/__napi_schedule to napi_schedule Christian Marangi
2023-10-03 14:51 ` [net-next PATCH v2 2/4] netdev: make napi_schedule return bool on NAPI successful schedule Christian Marangi
2023-10-03 14:51 ` [net-next PATCH v2 3/4] netdev: replace napi_reschedule with napi_schedule Christian Marangi
2023-10-05 16:11 ` Eric Dumazet
2023-10-05 16:32 ` Jakub Kicinski
2023-10-05 16:41 ` Eric Dumazet
2023-10-06 18:52 ` Christian Marangi [this message]
2023-10-08 7:00 ` Eric Dumazet
2023-10-03 14:51 ` [net-next PATCH v2 4/4] netdev: use napi_schedule bool instead of napi_schedule_prep/__napi_schedule Christian Marangi
2023-10-05 16:16 ` Eric Dumazet
2023-10-06 18:49 ` Christian Marangi
2023-10-08 7:08 ` Eric Dumazet
2023-10-08 18:27 ` Christian Marangi
2023-10-09 8:27 ` Eric Dumazet
2023-10-05 16:09 ` [net-next PATCH v2 1/4] netdev: replace simple napi_schedule_prep/__napi_schedule to napi_schedule Eric Dumazet
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