Re: [PATCH net 1/3] net: macb: never give hardware a NULL RX buffer
From: Théo Lebrun <theo.lebrun@bootlin.com>
Date: 2026-09-24 15:14:06
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Hello Jakub, On Thu Sep 24, 2026 at 3:47 AM CEST, Jakub Kicinski wrote:
On Tue, 22 Sep 2026 20:37:00 +0000 netdev-bot+sashiko@kernel.org wrote:quoted
- [High] gem_init_rx_ring() (drivers/net/ethernet/cadence/macb_main.c:2793) now sets… - [High] gem_init_rx_ring() now publishes MACB_BIT(RX_USED) on every RX descriptor of a queue, resets queue->rx_tail/rx_prepared_head and then…If the AI interprets the rx poll side correctly these seem like a major flaw in setting the USED bit :(
Yes the AI is correct (unsurprisingly). But two things: - before this patch what happened was that HW read the NULL descriptor, so not much better - we can detect in gem_rx() using our ring buffer cursors that tell us what we've managed to allocate, that we gem_rx() doesn't iterate over descriptors that haven't been allocated Thanks, -- Théo Lebrun, Bootlin Embedded Linux and Kernel engineering https://bootlin.com