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From: Jakub Kicinski <kuba@kernel.org>
To: Horatiu Vultur <horatiu.vultur@microchip.com>
Cc: <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<davem@davemloft.net>, <edumazet@google.com>, <pabeni@redhat.com>,
	<UNGLinuxDriver@microchip.com>
Subject: Re: [PATCH net 3/3] net: lan966x: Fix FDMA when MTU is changed
Date: Tue, 25 Oct 2022 19:34:05 -0700	[thread overview]
Message-ID: <20221025193405.1c8f6e74@kernel.org> (raw)
In-Reply-To: <20221023184838.4128061-4-horatiu.vultur@microchip.com>

On Sun, 23 Oct 2022 20:48:38 +0200 Horatiu Vultur wrote:
> +		mtu = lan_rd(lan966x, DEV_MAC_MAXLEN_CFG(port->chip_port));

I'm slightly confused about the vlan situation, does this return the
vlan hdr length when enabled? or vlans are always communicated
out-of-band so don't need to count here?

Unrelated potential issue I spotted:

        skb = build_skb(page_address(page), PAGE_SIZE << rx->page_order);       
        if (unlikely(!skb))                                                     
                goto unmap_page;                                                
                                                                                
        dma_unmap_single(lan966x->dev, (dma_addr_t)db->dataptr,                 
                         FDMA_DCB_STATUS_BLOCKL(db->status),                    
                         DMA_FROM_DEVICE);  

Are you sure it's legal to unmap with a different length than you
mapped? Seems questionable - you can unmap & ask the unmap to skip
the sync, then sync manually only the part that you care about - if you
want to avoid full sync.

What made me pause here is that you build_skb() and then unmap which is
also odd because normally (if unmap was passed full len) unmap could
wipe what build_skb() initialized.

  reply	other threads:[~2022-10-26  2:34 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-23 18:48 [PATCH net 0/3] net: lan966x: Fixes for when MTU is changed Horatiu Vultur
2022-10-23 18:48 ` [PATCH net 1/3] net: lan966x: Fix the MTU calculation Horatiu Vultur
2022-10-23 18:48 ` [PATCH net 2/3] net: lan966x: Adjust maximum frame size when vlan is enabled/disabled Horatiu Vultur
2022-10-23 18:48 ` [PATCH net 3/3] net: lan966x: Fix FDMA when MTU is changed Horatiu Vultur
2022-10-26  2:34   ` Jakub Kicinski [this message]
2022-10-26 18:35     ` Horatiu Vultur

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