From: Simon Horman <horms@kernel.org>
To: Vladimir Oltean <vladimir.oltean@nxp.com>
Cc: netdev@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Xiaoliang Yang <xiaoliang.yang_1@nxp.com>,
Claudiu Manoil <claudiu.manoil@nxp.com>,
Alexandre Belloni <alexandre.belloni@bootlin.com>,
UNGLinuxDriver@microchip.com, Andrew Lunn <andrew@lunn.ch>,
Florian Fainelli <f.fainelli@gmail.com>,
Michael Walle <michael@walle.cc>,
Richie Pearn <richard.pearn@nxp.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH net] net: dsa: felix: fix oversize frame dropping for always closed tc-taprio gates
Date: Fri, 18 Aug 2023 14:14:52 +0200 [thread overview]
Message-ID: <ZN9gvGTV4qXnFs3c@vergenet.net> (raw)
In-Reply-To: <20230817120111.3522827-1-vladimir.oltean@nxp.com>
On Thu, Aug 17, 2023 at 03:01:11PM +0300, Vladimir Oltean wrote:
> The blamed commit resolved a bug where frames would still get stuck at
> egress, even though they're smaller than the maxSDU[tc], because the
> driver did not take into account the extra 33 ns that the queue system
> needs for scheduling the frame.
>
> It now takes that into account, but the arithmetic that we perform in
> vsc9959_tas_remaining_gate_len_ps() is buggy, because we operate on
> 64-bit unsigned integers, so gate_len_ns - VSC9959_TAS_MIN_GATE_LEN_NS
> may become a very large integer if gate_len_ns < 33 ns.
>
> In practice, this means that we've introduced a regression where all
> traffic class gates which are permanently closed will not get detected
> by the driver, and we won't enable oversize frame dropping for them.
>
> Before:
> mscc_felix 0000:00:00.5: port 0: max frame size 1526 needs 12400000 ps, 1152000 ps for mPackets at speed 1000
> mscc_felix 0000:00:00.5: port 0 tc 0 min gate len 1000000, sending all frames
> mscc_felix 0000:00:00.5: port 0 tc 1 min gate len 0, sending all frames
> mscc_felix 0000:00:00.5: port 0 tc 2 min gate len 0, sending all frames
> mscc_felix 0000:00:00.5: port 0 tc 3 min gate len 0, sending all frames
> mscc_felix 0000:00:00.5: port 0 tc 4 min gate len 0, sending all frames
> mscc_felix 0000:00:00.5: port 0 tc 5 min gate len 0, sending all frames
> mscc_felix 0000:00:00.5: port 0 tc 6 min gate len 0, sending all frames
> mscc_felix 0000:00:00.5: port 0 tc 7 min gate length 5120 ns not enough for max frame size 1526 at 1000 Mbps, dropping frames over 615 octets including FCS
>
> After:
> mscc_felix 0000:00:00.5: port 0: max frame size 1526 needs 12400000 ps, 1152000 ps for mPackets at speed 1000
> mscc_felix 0000:00:00.5: port 0 tc 0 min gate len 1000000, sending all frames
> mscc_felix 0000:00:00.5: port 0 tc 1 min gate length 0 ns not enough for max frame size 1526 at 1000 Mbps, dropping frames over 1 octets including FCS
> mscc_felix 0000:00:00.5: port 0 tc 2 min gate length 0 ns not enough for max frame size 1526 at 1000 Mbps, dropping frames over 1 octets including FCS
> mscc_felix 0000:00:00.5: port 0 tc 3 min gate length 0 ns not enough for max frame size 1526 at 1000 Mbps, dropping frames over 1 octets including FCS
> mscc_felix 0000:00:00.5: port 0 tc 4 min gate length 0 ns not enough for max frame size 1526 at 1000 Mbps, dropping frames over 1 octets including FCS
> mscc_felix 0000:00:00.5: port 0 tc 5 min gate length 0 ns not enough for max frame size 1526 at 1000 Mbps, dropping frames over 1 octets including FCS
> mscc_felix 0000:00:00.5: port 0 tc 6 min gate length 0 ns not enough for max frame size 1526 at 1000 Mbps, dropping frames over 1 octets including FCS
> mscc_felix 0000:00:00.5: port 0 tc 7 min gate length 5120 ns not enough for max frame size 1526 at 1000 Mbps, dropping frames over 615 octets including FCS
>
> Fixes: 11afdc6526de ("net: dsa: felix: tc-taprio intervals smaller than MTU should send at least one packet")
> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Simon Horman <horms@kernel.org>
next prev parent reply other threads:[~2023-08-18 12:15 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-17 12:01 Vladimir Oltean
2023-08-18 12:14 ` Simon Horman [this message]
2023-08-19 1:50 ` patchwork-bot+netdevbpf
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ZN9gvGTV4qXnFs3c@vergenet.net \
--to=horms@kernel.org \
--cc=UNGLinuxDriver@microchip.com \
--cc=alexandre.belloni@bootlin.com \
--cc=andrew@lunn.ch \
--cc=claudiu.manoil@nxp.com \
--cc=davem@davemloft.net \
--cc=edumazet@google.com \
--cc=f.fainelli@gmail.com \
--cc=kuba@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=michael@walle.cc \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
--cc=richard.pearn@nxp.com \
--cc=vladimir.oltean@nxp.com \
--cc=xiaoliang.yang_1@nxp.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®