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From: Bruce Richardson <bruce.richardson@intel.com>
To: Daniil Iskhakov <dish@amicon.ru>
Cc: Anatoly Burakov <anatoly.burakov@intel.com>,
	Vladimir Medvedkin <vladimir.medvedkin@intel.com>, <dev@dpdk.org>,
	<stable@dpdk.org>, <sdl.dpdk@linuxtesting.org>, <rrv@amicon.ru>
Subject: Re: [PATCH] net/ixgbe: fix flow control frame byte adjustment
Date: Tue, 19 May 2026 15:44:41 +0100	[thread overview]
Message-ID: <agx3WX8nLoJT6JbS@bricha3-mobl1.ger.corp.intel.com> (raw)
In-Reply-To: <20260504145502.160806-1-dish@amicon.ru>

On Mon, May 04, 2026 at 05:55:02PM +0300, Daniil Iskhakov wrote:
> LXONTXC and LXOFFTXC are 32-bit counters for transmitted XON and
> XOFF packets. ixgbe_read_stats_registers() sums their deltas and uses
> the result to adjust the transmitted byte counters by the minimum
> Ethernet frame length.
> 
> The sum is currently computed as:
> 
> 	total = lxon + lxoff
> 
> Since both operands are 32-bit, the addition is performed in 32 bits
> and may wrap before the result is stored in total. The wrapped value is
> then used in the byte adjustment, which may make the software byte
> counters incorrect.
> 
> Make total 64-bit and cast lxon before the addition so the XON/XOFF
> packet sum and the following byte adjustment are computed without
> 32-bit overflow.
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Fixes: af75078fece3 ("first public release")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Daniil Iskhakov <dish@amicon.ru>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>


  reply	other threads:[~2026-05-19 14:44 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-05-04 14:55 [PATCH] net/ixgbe: fix flow control frame byte adjustment Daniil Iskhakov
2026-05-19 14:44 ` Bruce Richardson [this message]
2026-05-19 14:50   ` Bruce Richardson

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