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

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Message-ID: <e325467b-30e3-7031-831b-e47e3e23a9e0@gmail.com>
Date:   Wed, 15 Nov 2017 23:19:24 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        David Miller <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, Ard Biesheuvel <ard.biesheuvel@...aro.org>
Subject: Re: [PATCH RfC 1/2] net: phy: core: remove now uneeded disabling of
 interrupts

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.

> 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>
>> ---
>>  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;
>>  
>>
> 
>