netdev - Re: [PATCH v2] net: fec: Use unlocked timecounter reads for saving state

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Message-ID: <6f008565-b1a9-2826-79e9-85f235627016@prolan.hu>
Date:   Wed, 31 Aug 2022 15:09:09 +0200
From:   Csókás Bence <csokas.bence@...lan.hu>
To:     Andrew Lunn <andrew@...n.ch>
CC:     <netdev@...r.kernel.org>,
        Richard Cochran <richardcochran@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, <qiangqing.zhang@....com>,
        <kernel@...gutronix.de>, Marc Kleine-Budde <mkl@...gutronix.de>
Subject: Re: [PATCH v2] net: fec: Use unlocked timecounter reads for saving
 state


On 2022. 08. 30. 17:21, Andrew Lunn wrote:
> You are not taking a mutex, you are taking a spinlock. You can do that
> in atomic context. Can you protect everything which needs protecting
> with a spinlock? And avoid sleeping...

You are correct, the issue Marc experienced turns out to be caused by a 
`mutex_lock()` introduced in 6a4d7234ae9a3bb31181f348ade9bbdb55aeb5c5...

On 2022. 08. 31. 5:41, Richard Cochran wrote:
 > Just replace the mutex with a spinlock.

Will do. Disregard this patch and see "[PATCH] Use a spinlock to guard 
`fep->ptp_clk_on`" instead

Bence