From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mout-p-202.mailbox.org (mout-p-202.mailbox.org [80.241.56.172]) (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 9C2EE3EE1DB; Tue, 9 Jun 2026 08:37:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=80.241.56.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780994248; cv=none; b=XKQM2AR6TT6/tXBb6zORlQ8hsZ9tXGeh5rOTpISTvHhnkQvnoeofjq2FYYps1n3fR248mieYjrCnqD6byxRRSSh2kvQZK+k9rAMafv2EDoSoKJ2hIlWDVzgdQlHY23rR+M0RxF+jWj8u9XoqxKTh0AMvQ2hYn2xRWfTUJjXFsVg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780994248; c=relaxed/simple; bh=l7Exmz9p/uIitXB5p6TW0/WOEv3+e2EoOmnpCMBj2wc=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=fD6URl120PZWMavrFWIEplW6hXrCyrufglnyjOVOERPcl5W3ff3QRahfMtsCGnB0VF2XlEzob/edLq1CZm7LsE6x1Vp4YPSsesVyHdf2AifK9mry8zrfwV7MtblpV/Qb/rxxsTLmzVbnkRcwfOUS0v8PYwMBAQfkLeoeUUC7DnY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mailbox.org; spf=pass smtp.mailfrom=mailbox.org; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b=RPiYH9VX; arc=none smtp.client-ip=80.241.56.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mailbox.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mailbox.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b="RPiYH9VX" Received: from smtp1.mailbox.org (smtp1.mailbox.org [IPv6:2001:67c:2050:b231:465::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-p-202.mailbox.org (Postfix) with ESMTPS id 4gZMj80rBzz9tXD; Tue, 9 Jun 2026 10:37:16 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mailbox.org; s=mail20150812; t=1780994236; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=NeflN5T28HahSSS6B50cN92fDni13v9ufrgZcj6h5yI=; b=RPiYH9VXQKDM42/5vsxxIwbqpWCXmAWSGRa5js/gMS3D6qSjYnJ1RphKo0vO7Iyifj32qI f9m7KUqHr7kFocN4TPV49/mA+WI9nN2Mtr4WBW0TMkSb6Z18jJGf/nxBGKNaCUY/0kVCpa bC1OeNR1BAHN2zrmQrj98yrglCDOcYKzP+qAFY0uqzVBearFclMNMAZ1AvpLovt0NPtLVp zyKCLX2SB5jeL/SnhwsPXJPuegPBoLNUPm83mK+ZpaLTDQvHfF6cercjXYM4DxL0un+A+k QADS4O4H13SfmIZq/wryfYCVRtHQnsecuO20gRXkGSPSUxQ8CdtOXDIO/1AEAQ== Date: Tue, 9 Jun 2026 10:37:04 +0200 From: =?UTF-8?B?xYF1a2Fzeg==?= Majewski To: Jakub Kicinski Cc: andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, richardcochran@gmail.com, lgirdwood@gmail.com, nathan@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, krzk+dt@kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org, robh@kernel.org, Andrew Lunn Subject: Re: [net-next v24 3/7] net: mtip: Add buffers management functions to the L2 switch driver Message-ID: <20260609103704.443c0b57@wsk> In-Reply-To: <20260605021853.3594553-1-kuba@kernel.org> References: <20260601112437.2216043-4-lukasz.majewski@mailbox.org> <20260605021853.3594553-1-kuba@kernel.org> Organization: mailbox.org 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: quoted-printable X-MBO-RS-ID: 44354306cdec518454b X-MBO-RS-META: bmemnt9kx546q4uk8kkttrrnxxn5ua5h Hi Jakub, > This is an AI-generated review of your patch. The human sending this > email has considered the AI review valid, or at least plausible. > --- > net: mtip: Add buffers management functions to the L2 switch driver >=20 > This patch fills in mtip_alloc_buffers() and mtip_free_buffers() for > the MTIP L2 switch driver, replacing the previously empty stubs with > real page_pool setup/teardown and tx_bounce buffer allocation/free. >=20 > > diff --git a/drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c > > b/drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c index > > 1d1005a42306..5b5229ee411d 100644 --- > > a/drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c +++ > > b/drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c @@ -892,11 > > +892,101 @@ static void mtip_get_drvinfo(struct net_device *dev,=20 > > static void mtip_free_buffers(struct net_device *dev) > > { > > + struct mtip_ndev_priv *priv =3D netdev_priv(dev); > > + struct switch_enet_private *fep =3D priv->fep; > > + int i; > > + > > + for (i =3D 0; i < RX_RING_SIZE; i++) { > > + if (!fep->page[i]) > > + continue; > > + > > + page_pool_put_full_page(fep->page_pool, > > + fep->page[i], false); > > + fep->page[i] =3D NULL; > > + } > > + > > + page_pool_destroy(fep->page_pool); > > + fep->page_pool =3D NULL; > > + > > + for (i =3D 0; i < TX_RING_SIZE; i++) { > > + kfree(fep->tx_bounce[i]); > > + fep->tx_bounce[i] =3D NULL; > > + } > > +} =20 >=20 > [High] > Now that mtip_free_buffers() is no longer an empty stub, can the > mtip_open() error path tear down buffers that another active port is > still using? >=20 > Looking at mtip_open(): >=20 > if (fep->usage_count =3D=3D 0) { > ... > ret =3D mtip_alloc_buffers(dev); > if (ret) > goto mtip_alloc_buffers_err; > } > ... > ret =3D mtip_mii_probe(dev); > if (ret) > goto mtip_mii_probe_err; > ... > mtip_mii_probe_err: > mtip_free_buffers(dev); > mtip_alloc_buffers_err: > if (fep->usage_count =3D=3D 0) { > netif_napi_del(&fep->napi); > clk_disable(fep->clk_ipg); > } > return ret; >=20 > mtip_alloc_buffers() only runs when fep->usage_count =3D=3D 0, so the > page_pool, fep->page[] and fep->tx_bounce[] are shared across switch > ports and only allocated on first open. mtip_close() reflects this and > only calls mtip_free_buffers() when fep->usage_count =3D=3D 1. >=20 > When a second port is opened (fep->usage_count > 0) and > mtip_mii_probe() fails, the mtip_mii_probe_err label still calls > mtip_free_buffers() unconditionally, which destroys the page_pool and > frees the tx_bounce buffers that the first, still-active port is > using. >=20 > Should the mtip_mii_probe_err teardown also be guarded by > fep->usage_count =3D=3D 0 (or the labels reordered) so buffers are only > freed for the last user, similar to mtip_close()? >=20 > After this change the previously harmless call becomes a real > teardown, so the surviving port's NAPI path (mtip_switch_rx() and the > later mtip_update_cbd() refill) would dereference a freed > fep->page_pool and NULL fep->page[] / fep->tx_bounce[] entries > whenever the second port's PHY probe fails while the first port is up. >=20 > > =20 > > +static int mtip_create_page_pool(struct switch_enet_private *fep, > > int size) +{ =20 > [ ... ] > > +} > > =20 > > static int mtip_alloc_buffers(struct net_device *dev) > > { =20 > [ ... ] > > return 0; > > + > > + err: > > + mtip_free_buffers(dev); > > + return -ENOMEM; > > } > > =20 Thank you for sending the AI review. Please find my comments: - I've gone through them and yes, there are a few issues found. However, those are IMHO not critical ones. - Some issues are not valid at all - like concern what happens when the switch is run on multi processor chip - both imx287 and vf610 are single core chips. - It seems like the AI review is "progressing" - i.e. there were no issues found with v23 for this particular patch. I do guess that the new Orc Mode from [1] has found it. - I do guess that different AI agent would generate different review - The aforementioned issues could be addressed with a fix patches - dragging along (and preparing for upstream) patch set with ~3400 LOC (which is rejected by non-deterministic AI review) takes too much resources now. To sum up: ---------- The MTIP driver for v6.6 kernel (YPRR Scarthgap) with and without PREEMPT_RT for vf610 and imx287 as well as the v24 for net-next can be found at [2]. Links: [1] - https://netdev-ai.bots.linux.dev/ai-local.html [2] - https://github.com/lmajewski/linux-imx28-l2switch/branches --=20 Best regards, =C5=81ukasz Majewski