From: Andrew Lunn <andrew@lunn.ch>
To: "Íñigo Huguet" <ihuguet@redhat.com>
Cc: irusskikh@marvell.com, dbogdanov@marvell.com,
davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
pabeni@redhat.com, netdev@vger.kernel.org,
Li Liang <liali@redhat.com>
Subject: Re: [PATCH net] atlantic: fix deadlock at aq_nic_stop
Date: Sat, 15 Oct 2022 17:09:34 +0200 [thread overview]
Message-ID: <Y0rNLpmCjHVoO+D1@lunn.ch> (raw)
In-Reply-To: <CACT4oudn-sS16O7_+eihVYUqSTqgshbbqMFRBhgxkgytphsN-Q@mail.gmail.com>
> > Maybe the lock needs to be moved closer to what actually needs to be
> > protect? What is it protecting?
>
> It's protecting the operations of aq_macsec_enable and aq_macsec_work.
> The locking was closer to them, but the idea of this patch is to move
> the locking to an earlier moment so, in the case we need to abort, do
> it before changing anything.
aq_check_txsa_expiration() seems to be one of the issues? At least,
the lock is taken before and released afterwards. So what in
aq_check_txsa_expiration() requires the lock?
I don't like the use of rtnl_trylock(). It suggests the basic design is
wrong, or overly complex, and so probably not working correctly.
https://blog.ffwll.ch/2022/07/locking-engineering.html
Please try to identify what is being protected. If it is driver
internal state, could it be replaced with a driver mutex, rather than
RTNL? Or is it network stack as a whole state, which really does
require RTNL? If so, how do other drivers deal with this problem? Is
it specific to MACSEC? Does MACSEC have a design problem?
Andrew
next prev parent reply other threads:[~2022-10-15 15:09 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-14 10:34 [PATCH net] atlantic: fix deadlock at aq_nic_stop Íñigo Huguet
2022-10-14 12:13 ` Andrew Lunn
2022-10-14 12:43 ` Íñigo Huguet
2022-10-14 13:35 ` Andrew Lunn
2022-10-14 13:44 ` Íñigo Huguet
2022-10-15 15:09 ` Andrew Lunn [this message]
2022-10-17 7:22 ` Íñigo Huguet
2022-10-18 0:27 ` Andrew Lunn
2022-10-18 2:44 ` Jakub Kicinski
2022-10-18 6:15 ` Íñigo Huguet
2022-10-18 15:59 ` Jakub Kicinski
2022-10-19 6:18 ` Íñigo Huguet
2022-10-19 15:39 ` Jakub Kicinski
2022-10-20 7:46 ` Íñigo Huguet
2022-10-18 6:11 ` Íñigo Huguet
2022-10-20 7:53 ` [PATCH v2 " Íñigo Huguet
2022-10-20 8:55 ` Igor Russkikh
2022-10-20 16:17 ` Íñigo Huguet
2022-10-21 19:01 ` Íñigo Huguet
2022-10-24 9:30 ` patchwork-bot+netdevbpf
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