From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id BBB28C3ABAC for ; Tue, 6 May 2025 09:26:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=7erJ6D4MscaX/8GMAkhh6echRQy7e9Y89tGL2kE8J0M=; b=a64nKl+HhAPK5ZOwhjM2YNTGkd YUGTz+XY43F+nB4tmDV289D6Ti9L2arTsR6T7K9MtDeKczy9X5Jm6o1CC5skB+47wqNuLNVF672C9 1kqmbPNhuOQdtwp8GN1ViYTqavq+Sdx/YOw96mT0FAyQ4Yvj7TmB+ihCUNdkEQCLVd6zsW6i0CC17 icsRdS1XS/ZJd5Phznzg3W9zwRN7vUpGhI6iPQdHUC3EULrQzKq31h1oB7EVP0wh04RFyeojHl+VG Xp9uHWhbl2ElpllIfp4OdIm2R+LCh23+2HMwmWMq4WqSs9yI3ccOrMmMRKAgBQ/DzdJBmmREXGQYV vUIW4qSQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uCEYo-0000000BMZM-1BW2; Tue, 06 May 2025 09:25:58 +0000 Received: from pandora.armlinux.org.uk ([2001:4d48:ad52:32c8:5054:ff:fe00:142]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uCDqe-0000000BCMc-0lBE for linux-arm-kernel@lists.infradead.org; Tue, 06 May 2025 08:40:21 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=7erJ6D4MscaX/8GMAkhh6echRQy7e9Y89tGL2kE8J0M=; b=CdpldXB/2Q0l2OTVLNV2gpkRAG XfccCdj2iux3quft5JVSSqw/idGG0Gm3/pQmtQp+6Hxod0KxkK+jVhfPGlNxUlMgmzKD+/mTvSCyh 3jFMecGeHePRWEUYRWLPW74q7X75hCp91jo2htDud9PBzTe6JBlhxP5dsw0py85278EQgpAMD75ls cILdpReGXz2MKvgcOg9y93V1fbZsXZTVRau9wVlujcMsPvjfUXXwzkvoCQmwvc1KqNKIi4JzGK8U8 FRLpbI+nsHfh2Q9vEushCtnSQs8O0y+EpDjIkKDdDAIhCp87s70N3IfL4MlIFeFcYRQrYJdOXembm H3GAXrdA==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:33184) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1uCDqO-0005V2-1K; Tue, 06 May 2025 09:40:04 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.96) (envelope-from ) id 1uCDqM-0004f5-0o; Tue, 06 May 2025 09:40:02 +0100 Date: Tue, 6 May 2025 09:40:02 +0100 From: "Russell King (Oracle)" To: Andrew Lunn Cc: Heiner Kallweit , Alexandre Torgue , Alexei Starovoitov , Andrew Lunn , bpf@vger.kernel.org, Daniel Borkmann , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Jesper Dangaard Brouer , John Fastabend , Jon Hunter , linux-arm-kernel@lists.infradead.org, linux-stm32@st-md-mailman.stormreply.com, Maxime Coquelin , netdev@vger.kernel.org, Paolo Abeni , Thierry Reding Subject: Re: [PATCH net-next v2 2/4] net: stmmac: call phylink_carrier_*() in XDP functions Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250506_014020_359774_111FAD22 X-CRM114-Status: GOOD ( 50.12 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, May 06, 2025 at 09:36:57AM +0100, Russell King (Oracle) wrote: > On Fri, May 02, 2025 at 06:54:49PM +0100, Russell King (Oracle) wrote: > > On Fri, May 02, 2025 at 05:29:21PM +0200, Andrew Lunn wrote: > > > On Fri, May 02, 2025 at 02:35:36PM +0100, Russell King (Oracle) wrote: > > > > Phylink does not permit drivers to mess with the netif carrier, as > > > > this will de-synchronise phylink with the MAC driver. Moreover, > > > > setting and clearing the TE and RE bits via stmmac_mac_set() in this > > > > path is also wrong as the link may not be up. > > > > > > > > Replace the netif_carrier_on(), netif_carrier_off() and > > > > stmmac_mac_set() calls with the appropriate phylink_carrier_block() and > > > > phylink_carrier_unblock() calls, thereby allowing phylink to manage the > > > > netif carrier and TE/RE bits through the .mac_link_up() and > > > > .mac_link_down() methods. > > > > > > > > This change will have the side effect of printing link messages to > > > > the kernel log, even though the physical link hasn't changed state. > > > > This matches the carrier state that userspace sees, which has always > > > > "bounced". > > > > > > > > Note that RE should only be set after the DMA is ready to avoid the > > > > receive FIFO between the MAC and DMA blocks overflowing, so > > > > phylink_start() needs to be placed after DMA has been started. > > > > > > > > Signed-off-by: Russell King (Oracle) > > > > --- > > > > .../net/ethernet/stmicro/stmmac/stmmac_main.c | 20 +++++++++++-------- > > > > 1 file changed, 12 insertions(+), 8 deletions(-) > > > > > > > > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > > > > index f59a2363f150..ac27ea679b23 100644 > > > > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > > > > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > > > > @@ -6922,6 +6922,11 @@ void stmmac_xdp_release(struct net_device *dev) > > > > /* Ensure tx function is not running */ > > > > netif_tx_disable(dev); > > > > > > > > + /* Take down the software link. stmmac_xdp_open() must be called after > > > > + * this function to release this block. > > > > + */ > > > > + phylink_carrier_block(priv->phylink); > > > > + > > > > /* Disable NAPI process */ > > > > stmmac_disable_all_queues(priv); > > > > > > > > @@ -6937,14 +6942,10 @@ void stmmac_xdp_release(struct net_device *dev) > > > > /* Release and free the Rx/Tx resources */ > > > > free_dma_desc_resources(priv, &priv->dma_conf); > > > > > > > > - /* Disable the MAC Rx/Tx */ > > > > - stmmac_mac_set(priv, priv->ioaddr, false); > > > > - > > > > /* set trans_start so we don't get spurious > > > > * watchdogs during reset > > > > */ > > > > netif_trans_update(dev); > > > > - netif_carrier_off(dev); > > > > } > > > > > > > > > > > int stmmac_xdp_open(struct net_device *dev) > > > > @@ -7026,25 +7027,28 @@ int stmmac_xdp_open(struct net_device *dev) > > > > hrtimer_setup(&tx_q->txtimer, stmmac_tx_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); > > > > } > > > > > > > > - /* Enable the MAC Rx/Tx */ > > > > - stmmac_mac_set(priv, priv->ioaddr, true); > > > > - > > > > /* Start Rx & Tx DMA Channels */ > > > > stmmac_start_all_dma(priv); > > > > > > > > + /* Allow phylink to bring the software link back up. > > > > + * stmmac_xdp_release() must have been called prior to this. > > > > + */ > > > > > > This is counter intuitive. Why is release called before open? > > > > Indeed - and that should've been caught in the review where XDP was > > being added. > > > > > Looking into stmmac_xdp_set_prog() i think i get it. Even if there is > > > not a running XDP prog, stmmac_xdp_release() is called, and then > > > stmmac_xdp_open(). > > > > If there is a change of "do we have an XDP prog" state, then > > stmmac_xdp_release() is called to free all the current contexts to > > do with queue/descriptor management, and then stmmac_xdp_open() is > > called thereafter. These are doing a subset of .ndo_open/.ndo_release > > and I think that's where they're getting their naming from. > > > > The only possible sequence is: > > > > stmmac_open() > > then, on each XDP prog addition or removal, but not replacement: > > stmmac_xdp_release() > > stmmac_xdp_open() > > finally, > > stmmac_release() > > > > > Maybe these two functions need better names? prepare and commit? > > > > Yes, it's all counter intuitive, and there are various things about the > > XDP code that make it hard to follow. > > > > For example, stmmac_xdp_set_prog() leads you to think, because of the > > way the need_update variable is set, that looking for references to > > xdp_prog would show one where all the dependents are, but no, there's > > stmmac_xdp_is_enabled(), which is nice and readable, but could've > > been used in stmmac_xdp_set_prog() to make it more obvious what to > > grep for. > > > > Incidentally, if stmmac_xdp_open() fails to re-grab the interrupts, > > then it calls phylink_stop(), stmmac_hw_teardown(), and > > free_dma_desc_resources(). > > > > If one then set the interface administratively down, stmmac_release() > > gets called, which again calls phylink_stop(), free_dma_desc_resources() > > and stmmac_release_ptp(). > > > > stmmac_release_ptp() disables/unprepares clk_ptp_ref, and unregisters > > the PTP stuff. stmmac_hw_teardown() also disables/unprepares > > clk_ptp_ref, so we probably unbalance the clk API in this case... > > and probably much other stuff. > > > > Calling free_dma_desc_resources() twice calls functios such as > > free_dma_tx_desc_resources() twice, and it looks like that's not going > > to be healthy, calling dma_free_coherent() with the same arguments, > > double-releasing memory. Same for kfree(). Probably same for the RX > > stuff. > > > > Basically, if one messes with XDP in this driver, expect things to go > > bang and kill the kernel if something goes wrong with the whole > > xdp_release+xdp_open dance. > > > > Honestly, this needs a rewrite, but I currently know nowt about XDP. > > > > So, I'd suggest that the names of these functions is the least of the > > problems here. > > Well, this series has been discarded from patchwork. Shrug. I won't be > posting another version, stmmac can remain broken. I don't have a > suggestion on better names for these functions. ... and in any case, Andrew's comment would be a *separate* change to the subject of this series, so is not appropriate to be part of this series. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!