From: Heiner Kallweit <hkallweit1@gmail.com>
To: Eric Dumazet <edumazet@google.com>
Cc: Paolo Abeni <pabeni@redhat.com>, Jakub Kicinski <kuba@kernel.org>,
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: Wed, 15 May 2024 07:53:44 +0200 [thread overview]
Message-ID: <442303d8-ffaa-40dc-8f71-786bebde1366@gmail.com> (raw)
In-Reply-To: <CANn89iLgj0ph5gRWOA2M2J8N_4hQd3Ndm73gATR8WODXaOM_LA@mail.gmail.com>
On 14.05.2024 11:45, Eric Dumazet wrote:
> On Tue, May 14, 2024 at 8:52 AM Heiner Kallweit <hkallweit1@gmail.com> wrote:
>>
>> Ken reported that RTL8125b can lock up if gro_flush_timeout has the
>> default value of 20000 and napi_defer_hard_irqs is set to 0.
>> In this scenario device interrupts aren't disabled, what seems to
>> trigger some silicon bug under heavy load. I was able to reproduce this
>> behavior on RTL8168h.
>> Disabling device interrupts if NAPI is scheduled from a place other than
>> the driver's interrupt handler is a necessity in r8169, for other
>> drivers it may still be a performance optimization.
>>
>> Fixes: 7274c4147afb ("r8169: don't try to disable interrupts if NAPI is scheduled already")
>> Reported-by: Ken Milmore <ken.milmore@gmail.com>
>> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
>> ---
>> drivers/net/ethernet/realtek/r8169_main.c | 6 ++++--
>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
>> index e5ea827a2..01f0ca53d 100644
>> --- a/drivers/net/ethernet/realtek/r8169_main.c
>> +++ b/drivers/net/ethernet/realtek/r8169_main.c
>> @@ -4639,6 +4639,7 @@ static irqreturn_t rtl8169_interrupt(int irq, void *dev_instance)
>> {
>> struct rtl8169_private *tp = dev_instance;
>> u32 status = rtl_get_events(tp);
>> + int ret;
>>
>> if ((status & 0xffff) == 0xffff || !(status & tp->irq_mask))
>> return IRQ_NONE;
>> @@ -4657,10 +4658,11 @@ static irqreturn_t rtl8169_interrupt(int irq, void *dev_instance)
>> rtl_schedule_task(tp, RTL_FLAG_TASK_RESET_PENDING);
>> }
>>
>> - if (napi_schedule_prep(&tp->napi)) {
>> + ret = __napi_schedule_prep(&tp->napi);
>> + if (ret >= 0)
>> rtl_irq_disable(tp);
>> + if (ret > 0)
>> __napi_schedule(&tp->napi);
>> - }
>> out:
>> rtl_ack_events(tp, status);
>>
>
> I do not understand this patch.
>
> __napi_schedule_prep() would only return -1 if NAPIF_STATE_DISABLE was set,
> but this should not happen under normal operations ?
>
> A simple revert would avoid adding yet another NAPI helper.
Fine with me, I'll go with the revert for now.
prev parent reply other threads:[~2024-05-15 5:53 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
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 [this message]
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