netdev - Re: [PATCH v2] net: fec: Use a spinlock to guard `fep->ptp_clk

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Date:   Fri, 2 Sep 2022 08:47:34 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Csókás Bence <csokas.bence@...lan.hu>,
        netdev@...r.kernel.org
Cc:     Richard Cochran <richardcochran@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Francesco Dolcini <francesco.dolcini@...adex.com>,
        Andrew Lunn <andrew@...n.ch>, kernel@...gutronix.de,
        Marc Kleine-Budde <mkl@...gutronix.de>
Subject: Re: [PATCH v2] net: fec: Use a spinlock to guard `fep->ptp_clk_on`



On 9/2/2022 12:35 AM, Csókás Bence wrote:
> 
> On 2022. 09. 01. 18:26, Florian Fainelli wrote:
>>
>>>       schedule_delayed_work(&fep->time_keep, HZ);
>>>   }
>>> @@ -599,8 +593,6 @@ void fec_ptp_init(struct platform_device *pdev, 
>>> int irq_idx)
>>>       }
>>>       fep->ptp_inc = NSEC_PER_SEC / fep->cycle_speed;
>>> -    spin_lock_init(&fep->tmreg_lock);
>>
>> This change needs to be kept as there is no other code in the driver 
>> that would initialize the tmreg_lock otherwise. Try building a kernel 
>> with spinlock debugging enabled and you should see it barf with an 
>> incorrect spinlock bad magic.
> 
> `fec_ptp_init()` is called from `fec_probe()`, which init's the spinlock:
> 
>  > @@ -3907,7 +3908,7 @@ fec_probe(struct platform_device *pdev)
>  >         }
>  >
>  >         fep->ptp_clk_on = false;
>  > -       mutex_init(&fep->ptp_clk_mutex);
>  > +       spin_lock_init(&fep->tmreg_lock);

Ah indeed, I missed that, thanks!
-- 
Florian