netdev - Softirq error with mcp251xfd driver

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Message-ID: <20210310064626.GA11893@homes.emlix.com>
Date:   Wed, 10 Mar 2021 07:46:26 +0100
From:   Daniel Glöckner <dg@...ix.com>
To:     netdev@...r.kernel.org, linux-can@...r.kernel.org
Cc:     Marc Kleine-Budde <mkl@...gutronix.de>
Subject: Softirq error with mcp251xfd driver

Hi,

the mcp251xfd driver uses a threaded irq handler to queue skbs with the
can_rx_offload_* helpers. I get the following error on every packet until
the rate limit kicks in:

NOHZ tick-stop error: Non-RCU local softirq work is pending, handler #08!!!

Adding local_bh_disable/local_bh_enable around the can_rx_offload_* calls
gets rid of the error, but is that the correct way to fix this?
Internally the can_rx_offload code uses spin_lock_irqsave to safely
manipulate its queue.

Best regards,

  Daniel