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Date:   Mon, 28 Dec 2020 10:54:23 -0800
From:   Jakub Kicinski <kuba@kernel.org>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        =?UTF-8?B?Qmo=?= =?UTF-8?B?w7ZybiBUw7ZwZWw=?= 
        <bjorn.topel@intel.com>, Sasha Levin <sashal@kernel.org>
Subject: Re: [PATCH 5.10 462/717] ice, xsk: clear the status bits for the
 next_to_use descriptor
Message-ID: <20201228105423.46e77460@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
In-Reply-To: <20201228125043.105740628@linuxfoundation.org>
References: <20201228125020.963311703@linuxfoundation.org>
        <20201228125043.105740628@linuxfoundation.org>
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On Mon, 28 Dec 2020 13:47:40 +0100 Greg Kroah-Hartman wrote:
> From: Bj=C3=B6rn T=C3=B6pel <bjorn.topel@intel.com>
>=20
> [ Upstream commit 8d14768a7972b92c73259f0c9c45b969d85e3a60 ]
>=20
> On the Rx side, the next_to_use index points to the next item in the
> HW ring to be refilled/allocated, and next_to_clean points to the next
> item to potentially be processed.
>=20
> When the HW Rx ring is fully refilled, i.e. no packets has been
> processed, the next_to_use will be next_to_clean - 1. When the ring is
> fully processed next_to_clean will be equal to next_to_use. The latter
> case is where a bug is triggered.
>=20
> If the next_to_use bits are not cleared, and the "fully processed"
> state is entered, a stale descriptor can be processed.
>=20
> The skb-path correctly clear the status bit for the next_to_use
> descriptor, but the AF_XDP zero-copy path did not do that.
>=20
> This change adds the status bits clearing of the next_to_use
> descriptor.
>=20
> Fixes: 2d4238f55697 ("ice: Add support for AF_XDP")
> Signed-off-by: Bj=C3=B6rn T=C3=B6pel <bjorn.topel@intel.com>
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> Signed-off-by: Sasha Levin <sashal@kernel.org>

Oh wow, so much for Sasha waiting longer for code to get tested before
auto-pulling things into stable :/

I have this change and other changes here queued, but haven't sent the
submission yet.

How long is the auto-backporting delay in terms of calendar days?