From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 266033CD8BB; Fri, 20 Mar 2026 17:02:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774026147; cv=none; b=AZ21eYGm5w4FzAQFJqYTj1r1dN7N0L3XdWv3gZpOwi/fChLY8ev2w6JYlZ7TommknxcBOq89mSsf0ggGJK1haaWRhXr3QPZsnx6VAEnLxQc78nSrv+wJpviowl59m6P1fNaFFIFxUI7gYMHJ0cFF4pz4uZU8IunAD3mNinHtzpk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774026147; c=relaxed/simple; bh=OfqPN9mSDoWv8ARtiyLIw5c2e8KKvKcDWx3tLXQNcb8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rdvoV5G3TMXumVyKIZgX8FPUUYpWGCHY0p0En9toXT9wL+TDlcKDPlVWCtvS+Jc0S+xbYAzODlKjTa2YWvloQwokcjGjrCviJ5da1w/Krau7UOKNqvp/RWxPLR7sHcZlsG3rNQBa1O8Qa3UoIJ0P5jTTGPhFE2wWxWdkjbPAamA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=oo2MuGlK; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="oo2MuGlK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A5BE4C19425; Fri, 20 Mar 2026 17:02:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774026146; bh=OfqPN9mSDoWv8ARtiyLIw5c2e8KKvKcDWx3tLXQNcb8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oo2MuGlKgAX9A2COl7NtRyYUKFVEKK0O94zMonVfXhx3EMheLWC4Pp3kYfkTnSj1I +liIuY/gm5iKc+0cpG5gzC4FJZYRE76K4WqEAJTZxVDE8kFkbCx0MmiIHcpiqcvNlE lJWHAbJTqEnS6TItjLk/hQrtSy6shBVpoG937koVZwDzX/ZJCHgqS2pv0TM+BVWDHI Nd/YxHhNcuVYBN8pXdzBd7AUCa3oGUnbCU2gW8w0gpXWF4H0fID8xp6ITvNvunrPG2 7R5MRUj0vKEVbGk3Ge5gbhKBsMzuGfXOuUHi3tP8ewN9NmJjrdKM1xdf3pN2K5+SjD 6JyGaud83gBHg== From: Simon Horman To: nb@tipi-net.de Cc: Simon Horman , davem@davemloft.net, opendmb@gmail.com, john.fastabend@gmail.com, florian.fainelli@broadcom.com, daniel@iogearbox.net, arnd@arndb.de, bcm-kernel-feedback-list@broadcom.com, vikas.gupta@broadcom.com, bhargava.marreddy@broadcom.com, linux-kernel@vger.kernel.org, ast@kernel.org, edumazet@google.com, kuba@kernel.org, sdf@fomichev.me, ebiggers@google.com, hawk@kernel.org, andrew+netdev@lunn.ch, bpf@vger.kernel.org, pabeni@redhat.com, rajashekar.hudumula@broadcom.com, netdev@vger.kernel.org Subject: Re: [PATCH net-next v3 1/6] net: bcmgenet: convert RX path to page_pool Date: Fri, 20 Mar 2026 17:02:01 +0000 Message-ID: <20260320170201.102889-1-horms@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260319115402.353509-2-nb@tipi-net.de> References: <20260319115402.353509-2-nb@tipi-net.de> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit This is an AI-generated review of your patch. The human sending this email has considered the AI review valid, or at least plausible. For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html --- net: bcmgenet: convert RX path to page_pool Replace the per-packet __netdev_alloc_skb() + dma_map_single() in the RX path with page_pool, which provides efficient page recycling and DMA mapping management. This is a prerequisite for XDP support (which requires stable page-backed buffers rather than SKB linear data). Signed-off-by: Nicolai Buchwitz > diff --git a/drivers/net/ethernet/broadcom/Kconfig b/drivers/net/ethernet/broadcom/Kconfig > index cd7dddeb91dd..e3b9a5272406 100644 > --- a/drivers/net/ethernet/broadcom/Kconfig > +++ b/drivers/net/ethernet/broadcom/Kconfig [ ... ] > diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.c b/drivers/net/ethernet/broadcom/genet/bcmgenet.c > index 482a31e7b72b..7410034d9bdc 100644 > --- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c > +++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c [ ... ] > @@ -2747,6 +2758,31 @@ static void bcmgenet_init_tx_ring(struct bcmgenet_priv *priv, > netif_napi_add_tx(priv->dev, &ring->napi, bcmgenet_tx_poll); > } > > +static int bcmgenet_rx_ring_create_pool(struct bcmgenet_priv *priv, > + struct bcmgenet_rx_ring *ring) > +{ > + struct page_pool_params pp_params = { > + .order = 0, > + .flags = PP_FLAG_DMA_MAP | PP_FLAG_DMA_SYNC_DEV, > + .pool_size = ring->size, > + .nid = NUMA_NO_NODE, > + .dev = &priv->pdev->dev, > + .dma_dir = DMA_FROM_DEVICE, > + .offset = GENET_XDP_HEADROOM, > + .max_len = RX_BUF_LENGTH, > + }; > + > + ring->page_pool = page_pool_create(&pp_params); > + if (IS_ERR(ring->page_pool)) { > + int err = PTR_ERR(ring->page_pool); > + > + ring->page_pool = NULL; > + return err; > + } > + > + return 0; > +} > + > /* Initialize a RDMA ring */ > static int bcmgenet_init_rx_ring(struct bcmgenet_priv *priv, > unsigned int index, unsigned int size, > @@ -2765,10 +2801,17 @@ static int bcmgenet_init_rx_ring(struct bcmgenet_priv *priv, > ring->cb_ptr = start_ptr; > ring->end_ptr = end_ptr - 1; > > - ret = bcmgenet_alloc_rx_buffers(priv, ring); > + ret = bcmgenet_rx_ring_create_pool(priv, ring); > if (ret) > return ret; > > + ret = bcmgenet_alloc_rx_buffers(priv, ring); > + if (ret) { > + page_pool_destroy(ring->page_pool); > + ring->page_pool = NULL; > + return ret; > + } > + Does this leak pages if bcmgenet_alloc_rx_buffers() fails partway through? If bcmgenet_alloc_rx_buffers() successfully allocates pages for the first k iterations but then page_pool_alloc_pages() fails on iteration k+1, the pages stored in cb->rx_page for iterations 0 through k-1 are never returned to the page pool. When the error path calls page_pool_destroy(), the pool detects outstanding pages and defers cleanup, triggering periodic 'stalled pool shutdown' kernel warnings from page_pool_release_retry(). Then bcmgenet_init_dma's error path calls bcmgenet_free_rx_buffers(), which skips this ring entirely because ring->page_pool is NULL: bcmgenet_free_rx_buffers() { for (q = 0; q <= priv->hw_params->rx_queues; q++) { ring = &priv->rx_rings[q]; if (!ring->page_pool) continue; ... } } Should the error path iterate through the ring's cbs and call bcmgenet_free_rx_cb() for each one before destroying the page pool? The old code didn't have this issue because bcmgenet_free_rx_buffers() iterated all rx_cbs globally without checking for a per-ring page_pool. [ ... ]