netdev - Re: [PATCH net v1] lan743x: fix "BUG: invalid wait context" when setting rx mode

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Date:   Tue, 10 Nov 2020 17:55:09 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Sven Van Asbroeck <thesven73@...il.com>
Cc:     Bryan Whitehead <bryan.whitehead@...rochip.com>,
        David S Miller <davem@...emloft.net>,
        Microchip Linux Driver Support <UNGLinuxDriver@...rochip.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net v1] lan743x: fix "BUG: invalid wait context" when
 setting rx mode

On Mon,  9 Nov 2020 15:38:28 -0500 Sven Van Asbroeck wrote:
> From: Sven Van Asbroeck <thesven73@...il.com>
> 
> In the net core, the struct net_device_ops -> ndo_set_rx_mode()
> callback is called with the dev->addr_list_lock spinlock held.
> 
> However, this driver's ndo_set_rx_mode callback eventually calls
> lan743x_dp_write(), which acquires a mutex. Mutex acquisition
> may sleep, and this is not allowed when holding a spinlock.
> 
> Fix by removing the dp_lock mutex entirely. Its purpose is to
> prevent concurrent accesses to the data port. No concurrent
> accesses are possible, because the dev->addr_list_lock
> spinlock in the core only lets through one thread at a time.

Please remember about fixes tags, I've added:

Fixes: 23f0703c125b ("lan743x: Add main source files for new lan743x driver")

here. No idea what this lock was trying to protect from the start.

Applied, thanks!