From: Francois Romieu <romieu@fr.zoreil.com>
To: David Miller <davem@davemloft.net>
Cc: jemele@gmail.com, netdev@vger.kernel.org, jemele@google.com,
mlindner@marvell.com, stephen@networkplumber.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH net] sky2: Do not deadlock on sky2_hw_down
Date: Fri, 26 May 2017 00:05:20 +0200 [thread overview]
Message-ID: <20170525220520.GA4706@electric-eye.fr.zoreil.com> (raw)
In-Reply-To: <20170525.134205.884395652948196578.davem@davemloft.net>
David Miller <davem@davemloft.net> :
> From: Joshua Emele <jemele@gmail.com>
> Date: Wed, 24 May 2017 15:43:18 -0700
[...]
> > The sky2_hw_down uses sky2_tx_complete to free pending frames stuck in
> > the HW queue. Because sky2_hw_down can be called from a process context,
> > the call to u64_stats_update_begin can result in deadlock.
> >
> > Because the statistics do not require update as part of the sky2_hw_down
> > sequence, prevent the update to avoid the deadlock.
>
> I disagree. Taking the interface down should cause events in the
> statistics to be lost.
>
> You're going to have to find a way to fix this without eliding
> the stats increments.
NAPI processing is already disabled at this stage in the device close()
path (and sky2_netpoll() uses napi_schedule).
It's possible to add a conditionnal bh or irq disabling instruction to
silent the warning but it should not be needed at all.
--
Ueimor
next prev parent reply other threads:[~2017-05-25 22:05 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-24 22:43 Joshua Emele
2017-05-25 17:42 ` David Miller
2017-05-25 22:05 ` Francois Romieu [this message]
2017-05-25 17:54 ` Stephen Hemminger
2017-05-25 20:21 ` Joshua Emele
2017-05-25 22:05 ` Stephen Hemminger
2017-05-26 3:58 ` David Miller
2017-05-26 15:43 ` Stephen Hemminger
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