Re: [PATCH net-next] net: Write lock dev_base_lock without disabling bottom halves. - patchwork-bot+netdevbpf

From: patchwork-bot+netdevbpf@kernel.org
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: netdev@vger.kernel.org, lgoncalv@redhat.com, rostedt@goodmis.org,
	nilal@redhat.com, pezhang@redhat.com, davem@davemloft.net,
	kuba@kernel.org, tglx@linutronix.de
Subject: Re: [PATCH net-next] net: Write lock dev_base_lock without disabling bottom halves.
Date: Mon, 29 Nov 2021 12:20:10 +0000	[thread overview]
Message-ID: <163818841095.20614.3229662488535132477.git-patchwork-notify@kernel.org> (raw)
In-Reply-To: <20211126161529.hwqbkv6z2svox3zs@linutronix.de>

Hello:

This patch was applied to netdev/net-next.git (master)
by David S. Miller <davem@davemloft.net>:

On Fri, 26 Nov 2021 17:15:29 +0100 you wrote:
> The writer acquires dev_base_lock with disabled bottom halves.
> The reader can acquire dev_base_lock without disabling bottom halves
> because there is no writer in softirq context.
> 
> On PREEMPT_RT the softirqs are preemptible and local_bh_disable() acts
> as a lock to ensure that resources, that are protected by disabling
> bottom halves, remain protected.
> This leads to a circular locking dependency if the lock acquired with
> disabled bottom halves (as in write_lock_bh()) and somewhere else with
> enabled bottom halves (as by read_lock() in netstat_show()) followed by
> disabling bottom halves (cxgb_get_stats() -> t4_wr_mbox_meat_timeout()
> -> spin_lock_bh()). This is the reverse locking order.
> 
> [...]

Here is the summary with links:
  - [net-next] net: Write lock dev_base_lock without disabling bottom halves.
    https://git.kernel.org/netdev/net-next/c/fd888e85fe6b

You are awesome, thank you!
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