From: Florian Fainelli <florian.fainelli@broadcom.com>
To: Nicolai Buchwitz <nb@tipi-net.de>
Cc: netdev@vger.kernel.org, Cursor <cursoragent@cursor.com>,
Doug Berger <opendmb@gmail.com>,
Broadcom internal kernel review list
<bcm-kernel-feedback-list@broadcom.com>,
Andrew Lunn <andrew+netdev@lunn.ch>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Zak Kemble <zakkemble@gmail.com>, Simon Horman <horms@kernel.org>,
Ryo Takakura <ryotkkr98@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH net 7/8] net: bcmgenet: zero-initialize Transmit Status Block in bcmgenet_add_tsb
Date: Fri, 18 Sep 2026 10:41:53 -0700 [thread overview]
Message-ID: <d954c225-ed1f-4849-90c8-51891b1976e9@broadcom.com> (raw)
In-Reply-To: <f8918542ababe3af39ce6f2f5ee55948@tipi-net.de>
On 9/18/26 04:03, Nicolai Buchwitz wrote:
> Hi Florian
>
> On 18.9.2026 02:07, Florian Fainelli wrote:
>> bcmgenet_add_tsb() pushes 64 bytes of headroom onto the skb to form the
>> Transmit Status Block (TSB) but only assigns status->tx_csum_info when
>> skb->ip_summed == CHECKSUM_PARTIAL. For packets without checksum offload,
>> or for other fields within struct status_64, the status block contains
>> uninitialized stack/heap memory from previous skb operations.
>
> The MAC only reads tx_csum_info when the descriptor has DMA_TX_DO_CSUM,
> and bcmgenet_xmit() sets that only for CHECKSUM_PARTIAL.
> The stale value seems to be never used?
>
> Did you hit an actual failure? Otherwise this would be a 64 byte memset
> on every transmitted packet.
Nope this is entirely theoretical, and one could argue that this could
create a slight drop in performance, happy to drop that one as well
since we never really experienced any actual issue.
--
Florian
next prev parent reply other threads:[~2026-09-18 17:41 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-18 0:07 [PATCH net 0/8] net: bcmgenet: Collection of bug fixes Florian Fainelli
2026-09-18 0:07 ` [PATCH net 1/8] net: bcmgenet: fix 64-bit RTNL stats reading in ethtool on 32-bit systems Florian Fainelli
2026-09-18 10:13 ` Nicolai Buchwitz
2026-09-18 0:07 ` [PATCH net 2/8] net: bcmgenet: initialize u64 stats seq counter for all queues Florian Fainelli
2026-09-18 10:13 ` Nicolai Buchwitz
2026-09-18 0:07 ` [PATCH net 3/8] net: bcmgenet: do not skip WoL power up on GENET V1 Florian Fainelli
2026-09-18 10:16 ` Nicolai Buchwitz
2026-09-18 0:07 ` [PATCH net 4/8] net: bcmgenet: clean up RX NAPI on bcmgenet_init_rx_queues failure Florian Fainelli
2026-09-18 10:43 ` Nicolai Buchwitz
2026-09-18 17:39 ` Florian Fainelli
2026-09-18 0:07 ` [PATCH net 5/8] net: bcmgenet: acquire ring lock with BH disabled in bcmgenet_dump_tx_queue Florian Fainelli
2026-09-18 10:57 ` Nicolai Buchwitz
2026-09-18 17:40 ` Florian Fainelli
2026-09-18 0:07 ` [PATCH net 6/8] net: bcmgenet: validate Ethernet address in bcmgenet_set_mac_addr Florian Fainelli
2026-09-18 11:00 ` Nicolai Buchwitz
2026-09-18 0:07 ` [PATCH net 7/8] net: bcmgenet: zero-initialize Transmit Status Block in bcmgenet_add_tsb Florian Fainelli
2026-09-18 11:03 ` Nicolai Buchwitz
2026-09-18 17:41 ` Florian Fainelli [this message]
2026-09-18 0:07 ` [PATCH net 8/8] net: bcmgenet: mask DMA_TIMEOUT_MASK when reading DMA_RING0_TIMEOUT Florian Fainelli
2026-09-18 10:13 ` Nicolai Buchwitz
2026-09-18 0:12 ` [PATCH net 0/8] net: bcmgenet: Collection of bug fixes Florian Fainelli
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