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From: Jakub Kicinski <kuba@kernel.org>
To: Joe Damato <jdamato@fastly.com>
Cc: davem@davemloft.net, netdev@vger.kernel.org, edumazet@google.com,
	pabeni@redhat.com, andrew+netdev@lunn.ch, horms@kernel.org,
	sdf@fomichev.me, hramamurthy@google.com, kuniyu@amazon.com
Subject: Re: [PATCH net-next 2/8] net: designate XSK pool pointers in queues as "ops protected"
Date: Tue, 8 Apr 2025 07:59:08 -0700	[thread overview]
Message-ID: <20250408075908.27f834da@kernel.org> (raw)
In-Reply-To: <Z_SHQJ_pLOgz9vpM@LQ3V64L9R2>

On Mon, 7 Apr 2025 19:17:36 -0700 Joe Damato wrote:
> > -	xp_clear_dev(pool);
> > +	if (netdev) {
> > +		netdev_lock_ops(netdev);
> > +		xp_clear_dev(pool);
> > +		netdev_unlock_ops(netdev);
> > +	}
> >  	rtnl_unlock();  
> 
> Is it actually possible for netdev to be NULL here?

So I've been told in v1 review :) I should have probably linked to
previous postings, these patches had been a part of various series
before.

The code is indeed buggy, tho, we need to move the netdev = pool->netdev
assignment under rtnl_lock..

> I feel like it probably isn't, but if it were possible we'd need an
> else case here to xp_clear_dev(pool) without the netdev_lock_ops?

It does nothing when netdev is null. Actually, due to "other changes"
all callers of xp_clear_dev() are now wrapped in the lock. We can
move the locking inside that helper.

  reply	other threads:[~2025-04-08 14:59 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-07 19:01 [PATCH net-next 0/8] net: depend on instance lock for queue related netlink ops Jakub Kicinski
2025-04-07 19:01 ` [PATCH net-next 1/8] net: avoid potential race between netdev_get_by_index_lock() and netns switch Jakub Kicinski
2025-04-08  2:40   ` Joe Damato
2025-04-07 19:01 ` [PATCH net-next 2/8] net: designate XSK pool pointers in queues as "ops protected" Jakub Kicinski
2025-04-08  2:17   ` Joe Damato
2025-04-08 14:59     ` Jakub Kicinski [this message]
2025-04-07 19:01 ` [PATCH net-next 3/8] netdev: add "ops compat locking" helpers Jakub Kicinski
2025-04-08  2:41   ` Joe Damato
2025-04-07 19:01 ` [PATCH net-next 4/8] netdev: don't hold rtnl_lock over nl queue info get when possible Jakub Kicinski
2025-04-08  2:28   ` Joe Damato
2025-04-07 19:01 ` [PATCH net-next 5/8] xdp: double protect netdev->xdp_flags with netdev->lock Jakub Kicinski
2025-04-08  2:30   ` Joe Damato
2025-04-07 19:01 ` [PATCH net-next 6/8] netdev: depend on netdev->lock for xdp features Jakub Kicinski
2025-04-08  2:31   ` Joe Damato
2025-04-07 19:01 ` [PATCH net-next 7/8] docs: netdev: break down the instance locking info per ops struct Jakub Kicinski
2025-04-08  2:34   ` Joe Damato
2025-04-08 15:08     ` Jakub Kicinski
2025-04-07 19:01 ` [PATCH net-next 8/8] netdev: depend on netdev->lock for qstats in ops locked drivers Jakub Kicinski
2025-04-08  2:37   ` Joe Damato
2025-04-08  0:28 ` [PATCH net-next 0/8] net: depend on instance lock for queue related netlink ops Stanislav Fomichev

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