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Tue, 7 Jul 2026 16:06:52 +0530 (IST) X-Virus-Scanned: amavis at couthit.local Received: from zimbra.couthit.local ([127.0.0.1]) by localhost (zimbra.couthit.local [127.0.0.1]) (amavis, port 10026) with ESMTP id Xgrw10G8zfdZ; Tue, 7 Jul 2026 16:06:52 +0530 (IST) Received: from zimbra.couthit.local (zimbra.couthit.local [10.10.10.103]) by zimbra.couthit.local (Postfix) with ESMTP id B07661B071DC; Tue, 7 Jul 2026 16:06:52 +0530 (IST) Date: Tue, 7 Jul 2026 16:06:52 +0530 (IST) From: Parvathi Pudi To: Paolo Abeni Cc: parvathi , andrew+netdev , davem , edumazet , kuba , danishanwar , rogerq , pmohan , afd , basharath , arnd , linux-kernel , netdev , linux-arm-kernel , pratheesh , j-rameshbabu , Vignesh Raghavendra , praneeth , srk , rogerq , m-malladi , krishna , mohan Message-ID: <683548159.1585651.1783420612671.JavaMail.zimbra@couthit.local> In-Reply-To: <20260706091338.134754-1-pabeni@redhat.com> References: <20260630124958.894360-4-parvathi@couthit.com> <20260706091338.134754-1-pabeni@redhat.com> Subject: Re: [PATCH net-next v2 3/3] net: ti: icssm-prueth: Support duplicate HW offload feature for HSR and PRP Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Mailer: Zimbra 9.0.0_ZEXTRAS_20240927 (ZimbraWebClient - GC138 (Linux)/9.0.0_ZEXTRAS_20240927) Thread-Topic: icssm-prueth: Support duplicate HW offload feature for HSR and PRP Thread-Index: 1L122pWSAIHcS+z+0TJ+oGlKhvBb9Q== X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - server.couthit.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - couthit.com X-Get-Message-Sender-Via: server.couthit.com: authenticated_id: smtp@couthit.com X-Authenticated-Sender: server.couthit.com: smtp@couthit.com X-Source: X-Source-Args: X-Source-Dir: Hi, > From: AI Reviewer > > This is an AI-generated review of your patch. The human sending this > email has considered the AI review valid, or at least plausible. > Full review at: https://sashiko.dev/ > --- > net: ti: icssm-prueth: Support duplicate HW offload feature for HSR and PRP > > This commit introduces hardware duplicate offload for HSR and PRP modes. It > implements a common shared queue between the two ports, writing frames once > to OCMC RAM and relying on the firmware to replicate the transmission. > >> diff --git a/drivers/net/ethernet/ti/icssm/icssm_prueth.c >> b/drivers/net/ethernet/ti/icssm/icssm_prueth.c >> index 2ab78a98f8568..cbe666a212c3b 100644 >> --- a/drivers/net/ethernet/ti/icssm/icssm_prueth.c >> +++ b/drivers/net/ethernet/ti/icssm/icssm_prueth.c >> @@ -97,6 +125,17 @@ static void icssm_prueth_write_reg(struct prueth *prueth, >> static enum pruss_mem pruss_mem_ids[] = { PRUSS_MEM_DRAM0, PRUSS_MEM_DRAM1, >> PRUSS_MEM_SHRD_RAM2 }; >> >> +struct prp_txopt_rct { >> + __be16 sequence_nr; >> + __be16 lan_id_and_lsdu_size; >> + __be16 prp_suffix; >> +}; > > [Severity: High] > Does this structure definition need the __packed attribute? > > This struct consists of three 16-bit fields but lacks the __packed attribute, > so it inherits a 2-byte alignment requirement. Later in > icssm_prueth_tx_enqueue, a pointer to this structure is derived directly > from skb_tail_pointer. > > If an ethernet frame payload has an odd byte length, wouldn't casting and > dereferencing this pointer cause an unaligned 16-bit memory access, resulting > in hardware traps or panics on architectures that do not support it? > > [ ... ] >> @@ -549,15 +588,24 @@ static int icssm_prueth_tx_enqueue(struct prueth_emac >> *emac, > [ ... ] >> + other_emac = emac->prueth->emac[(emac->port_id == PRUETH_PORT_MII0) ? >> + PRUETH_PORT_MII1 - 1 : PRUETH_PORT_MII0 - 1]; >> + >> + if (prueth_is_lre(prueth) && (emac->link || other_emac->link)) >> + link_up = true; > > [Severity: High] > Could this logical OR cause the shared transmission queue to stall completely > if only one of the slave links goes down? > > If one port loses its link, its emac->link is 0, but the other active port > will still evaluate link_up as true. The active port would continue sending > duplicate frames to the shared queue. > > [ ... ] >> @@ -605,6 +659,29 @@ static int icssm_prueth_tx_enqueue(struct prueth_emac >> *emac, > [ ... ] >> + if (free_blocks_other_port < free_blocks) >> + free_blocks = free_blocks_other_port; >> + } > > [Severity: High] > Following up on the link_up logic above, since the available queue space is > bounded by the slowest reader here, wouldn't the inactive port's read pointer > remain frozen? > > This appears to exhaust the free_blocks pool, causing the active port to > eventually spin and return -ENOBUFS permanently, defeating the redundancy. > > [ ... ] >> + } else { >> + /* Read PRP RCT to extract sequence number and LAN ID */ >> + struct prp_txopt_rct *rct = >> + (struct prp_txopt_rct *)(skb_tail_pointer(skb) - >> + ICSSM_LRE_TAG_SIZE); >> + >> + if (rct->prp_suffix == htons(ETH_P_PRP)) { > > [Severity: High] > Is it safe to directly dereference rct->prp_suffix here? > > As mentioned above regarding the struct definition, this might lead to an > unaligned memory access on certain architectures. Perhaps using the > get_unaligned_be16 helper would be safer here, or adding the __packed > attribute to the structure definition. > > [ ... ] >> @@ -1341,18 +1516,30 @@ static enum netdev_tx icssm_emac_ndo_start_xmit(struct >> sk_buff *skb, > [ ... ] >> + raw_spin_lock(lock_queue); >> + ret = icssm_prueth_tx_enqueue(emac, skb, qid); >> + raw_spin_unlock(lock_queue); > > [Severity: High] > Does this need to use the irqsave variant to protect against cross-device > deadlocks with netpoll? > > The lre_host_queue_lock is shared between the two ports. If a hardirq > preempts a CPU while it holds this lock during a transmission, and the > interrupt handler invokes a printk that triggers netconsole over the second > interface, netpoll might bypass the netif_tx_lock. > > When the second interface calls into ndo_start_xmit, it would attempt to > acquire the exact same lre_host_queue_lock, causing it to spin forever on > the same CPU. > -- > This is an AI-generated review. We are in the process of reviewing the comments and will revert with additional details. Thanks and Regards, Parvathi.