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From: Jakub Kicinski <kuba@kernel.org>
To: Qingfang Deng <dqfext@gmail.com>
Cc: Andrew Lunn <andrew+netdev@lunn.ch>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Paolo Abeni <pabeni@redhat.com>,
	linux-ppp@vger.kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, Felix Fietkau <nbd@nbd.name>
Subject: Re: [PATCH net-next] ppp: enable TX scatter-gather
Date: Tue, 16 Sep 2025 07:57:21 -0700	[thread overview]
Message-ID: <20250916075721.273ea979@kernel.org> (raw)
In-Reply-To: <CALW65jYgDYxXfWFmwYBjXfNtqWqZ7VDWPYsbzAH_EzcRtyn0DQ@mail.gmail.com>

On Tue, 16 Sep 2025 10:57:49 +0800 Qingfang Deng wrote:
> Hi Jakub,
> 
> On Tue, Sep 16, 2025 at 9:10 AM Jakub Kicinski <kuba@kernel.org> wrote:
> > Seems a bit racy. We can't netdev_update_features() under the spin lock
> > so there's going to be a window of time where datapath will see new
> > state but netdev flags won't be cleared, yet?
> >
> > We either need to add a explicit linearization check in the xmit path,
> > or always reset the flags to disabled before we start tweaking the
> > config and re-enable after config (tho the latter feels like a bit of
> > a hack).  
> 
> Can I modify dev->features directly under the spin lock (without
> .ndo_fix_features) ?

Hm, I'm not aware of a reason not to. You definitely need to hold
rtnl_lock, and call netdev_update_features() after.

  reply	other threads:[~2025-09-16 14:57 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-09-12  9:59 [PATCH net-next] ppp: enable TX scatter-gather Qingfang Deng
2025-09-16  1:10 ` Jakub Kicinski
2025-09-16  2:57   ` Qingfang Deng
2025-09-16 14:57     ` Jakub Kicinski [this message]
2025-09-17 11:00       ` Qingfang Deng
2025-09-17 21:14         ` Jakub Kicinski

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