netdev - Re: [PATCH RfC 1/2] net: phy: core: remove now uneeded disabling of interrupts

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Message-ID: <CAKv+Gu904fbsRSZdnCU=qSbsuLamf-=Si5TtS7qX0RhH=0qmdA@mail.gmail.com>
Date:   Thu, 16 Nov 2017 09:51:21 +0000
From:   Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:     Heiner Kallweit <hkallweit1@...il.com>
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        David Miller <davem@...emloft.net>,
        "<netdev@...r.kernel.org>" <netdev@...r.kernel.org>
Subject: Re: [PATCH RfC 1/2] net: phy: core: remove now uneeded disabling of interrupts

On 15 November 2017 at 22:19, Heiner Kallweit <hkallweit1@...il.com> wrote:
> Am 15.11.2017 um 23:04 schrieb Florian Fainelli:
>> On 11/12/2017 01:08 PM, Heiner Kallweit wrote:
>>> After commits c974bdbc3e "net: phy: Use threaded IRQ, to allow IRQ from
>>> sleeping devices" and 664fcf123a30 "net: phy: Threaded interrupts allow
>>> some simplification" all relevant code pieces run in process context
>>> anyway and I don't think we need the disabling of interrupts any longer.
>>>
>>> Interestingly enough, latter commit already removed the comment
>>> explaining why interrupts need to be temporarily disabled.
>>>
>>> On my system phy interrupt mode works fine with this patch.
>>> However I may miss something, especially in the context of shared phy
>>> interrupts, therefore I'd appreciate if more people could test this.
>>
>> I am not currently in a position to test this, but this looks very
>> similar, if not identical to what Ard submitted a few days earlier:
>>
>
> Thanks for the hint. Indeed it's exactly the same patch, so the one
> sent by me can be disregarded.
>

Well, it does appear your patch is more complete. Another difference
is that I actually need this change to fix an issue with a
hierarchical irqchip stacked on top of the GIC.


>> https://patchwork.kernel.org/patch/10048901/
>>
>> Since net-next is closed at the moment, that should allow us to give
>> this some good amount of testing.
>>
>> Thanks
>>
>>>
>>> Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>

For the record

Acked-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>

Dear maintainers,

Please take whichever of these patches looks more correct to you.

Thanks,
Ard.

>>> ---
>>>  drivers/net/phy/phy.c | 26 ++------------------------
>>>  include/linux/phy.h   |  1 -
>>>  2 files changed, 2 insertions(+), 25 deletions(-)
>>>
>>> diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
>>> index 2b1e67bc1..b3784c9a2 100644
>>> --- a/drivers/net/phy/phy.c
>>> +++ b/drivers/net/phy/phy.c
>>> @@ -629,9 +629,6 @@ static irqreturn_t phy_interrupt(int irq, void *phy_dat)
>>>      if (PHY_HALTED == phydev->state)
>>>              return IRQ_NONE;                /* It can't be ours.  */
>>>
>>> -    disable_irq_nosync(irq);
>>> -    atomic_inc(&phydev->irq_disable);
>>> -
>>>      phy_change(phydev);
>>>
>>>      return IRQ_HANDLED;
>>> @@ -689,7 +686,6 @@ static int phy_disable_interrupts(struct phy_device *phydev)
>>>   */
>>>  int phy_start_interrupts(struct phy_device *phydev)
>>>  {
>>> -    atomic_set(&phydev->irq_disable, 0);
>>>      if (request_threaded_irq(phydev->irq, NULL, phy_interrupt,
>>>                               IRQF_ONESHOT | IRQF_SHARED,
>>>                               phydev_name(phydev), phydev) < 0) {
>>> @@ -716,13 +712,6 @@ int phy_stop_interrupts(struct phy_device *phydev)
>>>
>>>      free_irq(phydev->irq, phydev);
>>>
>>> -    /* If work indeed has been cancelled, disable_irq() will have
>>> -     * been left unbalanced from phy_interrupt() and enable_irq()
>>> -     * has to be called so that other devices on the line work.
>>> -     */
>>> -    while (atomic_dec_return(&phydev->irq_disable) >= 0)
>>> -            enable_irq(phydev->irq);
>>> -
>>>      return err;
>>>  }
>>>  EXPORT_SYMBOL(phy_stop_interrupts);
>>> @@ -736,7 +725,7 @@ void phy_change(struct phy_device *phydev)
>>>      if (phy_interrupt_is_valid(phydev)) {
>>>              if (phydev->drv->did_interrupt &&
>>>                  !phydev->drv->did_interrupt(phydev))
>>> -                    goto ignore;
>>> +                    return;
>>>
>>>              if (phy_disable_interrupts(phydev))
>>>                      goto phy_err;
>>> @@ -748,27 +737,16 @@ void phy_change(struct phy_device *phydev)
>>>      mutex_unlock(&phydev->lock);
>>>
>>>      if (phy_interrupt_is_valid(phydev)) {
>>> -            atomic_dec(&phydev->irq_disable);
>>> -            enable_irq(phydev->irq);
>>> -
>>>              /* Reenable interrupts */
>>>              if (PHY_HALTED != phydev->state &&
>>>                  phy_config_interrupt(phydev, PHY_INTERRUPT_ENABLED))
>>> -                    goto irq_enable_err;
>>> +                    goto phy_err;
>>>      }
>>>
>>>      /* reschedule state queue work to run as soon as possible */
>>>      phy_trigger_machine(phydev, true);
>>>      return;
>>>
>>> -ignore:
>>> -    atomic_dec(&phydev->irq_disable);
>>> -    enable_irq(phydev->irq);
>>> -    return;
>>> -
>>> -irq_enable_err:
>>> -    disable_irq(phydev->irq);
>>> -    atomic_inc(&phydev->irq_disable);
>>>  phy_err:
>>>      phy_error(phydev);
>>>  }
>>> diff --git a/include/linux/phy.h b/include/linux/phy.h
>>> index dc82a07cb..8a87e441f 100644
>>> --- a/include/linux/phy.h
>>> +++ b/include/linux/phy.h
>>> @@ -468,7 +468,6 @@ struct phy_device {
>>>      /* Interrupt and Polling infrastructure */
>>>      struct work_struct phy_queue;
>>>      struct delayed_work state_queue;
>>> -    atomic_t irq_disable;
>>>
>>>      struct mutex lock;
>>>
>>>
>>
>>
>