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From: Jakub Kicinski <kuba@kernel.org>
To: Alexander Lobakin <aleksander.lobakin@intel.com>
Cc: Eric Dumazet <edumazet@google.com>,
	Heiner Kallweit <hkallweit1@gmail.com>,
	Paolo Abeni <pabeni@redhat.com>,
	David Miller <davem@davemloft.net>,
	Realtek linux nic maintainers <nic_swsd@realtek.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	Ken Milmore <ken.milmore@gmail.com>
Subject: Re: [PATCH net 2/2] r8169: disable interrupts also for GRO-scheduled NAPI
Date: Tue, 14 May 2024 07:11:00 -0700	[thread overview]
Message-ID: <20240514071100.70fcca3e@kernel.org> (raw)
In-Reply-To: <CANn89i+yKgXGHUyJxVLYTAMKj7wpoV+8X7UR8cWh75yxVLSA6Q@mail.gmail.com>

On Tue, 14 May 2024 13:05:55 +0200 Eric Dumazet wrote:
> > napi_schedule()         // we disabled interrupts
> > napi_poll()             // we polled < budget frames
> > napi_complete_done()    // reenable the interrupts, no repoll
> >   hrtimer_start()       // GRO flush is queued
> >     napi_schedule()
> >       napi_poll()       // GRO flush, BUT interrupts are enabled

I thought the bug is because of a race with disable.
But there's already a synchronize_net() after disable, so NAPI poll
must fully exit before we mask in rtl8169_cleanup().

If the bug is double-enable you describe the fix is just making 
the race window smaller. But I don't think that's the bug.

BTW why are events only acked in rtl8169_interrupt() and not
rtl8169_poll()? 

  parent reply	other threads:[~2024-05-14 14:11 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-05-14  6:49 [PATCH net 0/2] r8169: Fix GRO-related issue with not disabled device interrupts Heiner Kallweit
2024-05-14  6:50 ` [PATCH net 1/2] net: add napi_schedule_prep variant with more granular return value Heiner Kallweit
2024-05-14 11:07   ` Eric Dumazet
2024-05-14 11:40     ` Heiner Kallweit
2024-05-14  6:52 ` [PATCH net 2/2] r8169: disable interrupts also for GRO-scheduled NAPI Heiner Kallweit
2024-05-14  9:45   ` Eric Dumazet
2024-05-14 10:52     ` Alexander Lobakin
2024-05-14 11:05       ` Eric Dumazet
2024-05-14 11:17         ` Alexander Lobakin
2024-05-14 14:27           ` Eric Dumazet
2024-05-14 11:29         ` Heiner Kallweit
2024-05-14 14:11         ` Jakub Kicinski [this message]
2024-05-14 16:35           ` Heiner Kallweit
2024-05-14 16:49             ` Jakub Kicinski
2024-05-14 17:09               ` Heiner Kallweit
2024-05-14 17:47                 ` Jakub Kicinski
2024-05-14 17:49                   ` Jakub Kicinski
2024-05-14 20:47                     ` Ken Milmore
2024-05-15  5:53     ` Heiner Kallweit

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