From: Jakub Kicinski <kuba@kernel.org>
To: Dragos Tatulea <dtatulea@nvidia.com>
Cc: "Björn Töpel" <bjorn@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
"Eric Dumazet" <edumazet@google.com>,
"Paolo Abeni" <pabeni@redhat.com>,
"Simon Horman" <horms@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Martin Karsten" <mkarsten@uwaterloo.ca>,
"Gal Pressman" <gal@nvidia.com>,
"Tariq Toukan" <tariqt@nvidia.com>, "Joe Damato" <joe@dama.to>,
"Frederik Deweerdt" <fdeweerdt@fastly.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH net-next 1/2] net: napi: Fix interrupts permanently disabled during busy poll
Date: Mon, 4 May 2026 18:00:04 -0700 [thread overview]
Message-ID: <20260504180004.7b9955eb@kernel.org> (raw)
In-Reply-To: <4onzzvtgdyj5k4himhtv4dsga4dnunk4ppjyqgam6us44biear@7vvozjz2ywrr>
On Mon, 4 May 2026 11:30:47 +0000 Dragos Tatulea wrote:
> > > That would also follow the scheme in napi_schedule_done(). (Note that
> > > swapping arm/clear does mean that we can get a wasted-timer outcome.)
> > >
> > If it is wasted is fine. I figured that this could end up with a timer
> > scheduled after the napi deletion:
> >
> > 1. busy_poll_stop(): clears SCHED bit.
> > 2. napi_disable() runs past SCHED wait, cancels timer and caller
> > deletes napi mem.
> > 3. busy_poll_stop(): napi->timer is armed but napi is freed memory
> > by now.
> >
> > What am I missing here?
> >
> Gentle ping. Once I understand how/why the above is incorrect I can
> update the patch and send it.
Eh, I didn't respond cause I got depressed. Look around for the pattern
you are calling incorrect in existing code and you'll figure out why...
next prev parent reply other threads:[~2026-05-05 1:00 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-28 17:51 [RFC PATCH net-next 0/2] net: napi: Fix timer arming during busy poll timeout Dragos Tatulea
2026-04-28 17:51 ` [RFC PATCH net-next 1/2] net: napi: Fix interrupts permanently disabled during busy poll Dragos Tatulea
2026-04-28 23:40 ` Jakub Kicinski
2026-04-29 0:04 ` Martin Karsten
2026-04-29 0:31 ` Jakub Kicinski
2026-04-29 8:13 ` Dragos Tatulea
2026-04-29 22:52 ` Jakub Kicinski
2026-04-29 0:38 ` Jakub Kicinski
2026-04-29 8:43 ` Dragos Tatulea
2026-04-29 12:13 ` Björn Töpel
2026-04-29 12:43 ` Dragos Tatulea
2026-05-04 11:30 ` Dragos Tatulea
2026-05-05 1:00 ` Jakub Kicinski [this message]
2026-04-28 17:51 ` [RFC PATCH net-next 2/2] net: napi: Skip poll when arming GRO timer in " Dragos Tatulea
2026-04-29 0:37 ` Jakub Kicinski
2026-04-29 1:02 ` Martin Karsten
2026-04-29 12:37 ` Björn Töpel
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