From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.tipi-net.de (mail.tipi-net.de [194.13.80.246]) (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 E03C03CCFAE; Thu, 2 Apr 2026 11:35:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=194.13.80.246 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775129749; cv=none; b=hP4pU0xioMTXVVXf4w1391oHK7xM7jqs/ICUityrXE8/Hu3v3kpoml1M5eq0XQmEmMBZtMHuFOlwwLYY7yksegdzj9PGOo3io2MT/nq88gklISsJl0wqmfwizS1SXOiaAbGVlqJAZviTNcrpLzY/hxKS4fi6PeJfCEx66Jh2zzU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775129749; c=relaxed/simple; bh=DDcpPxNStIKhIOddN8K9dB6cJ3YY5lGjbE25N3Iu3XM=; h=MIME-Version:Date:From:To:Cc:Subject:In-Reply-To:References: Message-ID:Content-Type; b=YS+COqG5Dvr8BFsi3cQKRS6f6D220aTrkMsQgmBKmD0Mv5X3CGEq9ZkEUE/D0zSqHOesRUWn/d//vscMAcZU+ud9CQTCelSMYKmXiZqUY9SlO1IdFwLO6qBdNepAjdq+ta2TtOfXAfcPnQWZqauxw5QQrFRuPKrSd/JvA1ahoz8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=tipi-net.de; spf=pass smtp.mailfrom=tipi-net.de; dkim=pass (2048-bit key) header.d=tipi-net.de header.i=@tipi-net.de header.b=ETAGn2VG; arc=none smtp.client-ip=194.13.80.246 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=tipi-net.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=tipi-net.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=tipi-net.de header.i=@tipi-net.de header.b="ETAGn2VG" Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 37848A5889; Thu, 2 Apr 2026 13:35:37 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tipi-net.de; s=dkim; t=1775129738; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:references; bh=KC1FZpvBCsFRD+ZZsA1/QCAOrkb0VRBzQzjA60MBHPM=; b=ETAGn2VGHKTlOvxUNI+DlLDU3qW+DRxCyTCUUpDTIObVk92IXg7GpbCULFxxYz3D/TYM/t LtOViG4Akg8vf/GQhpOW41Hv3Q9a3U71/k5VNhspHO3Pg59Y/Ed2v5RzYCl5n8cnqTwGnk iYCTI6oMBfgX4Nx4qJSOiyMgI8Mpvz8A8VspSylPzLflosYPvclh8s5DmVPWHfit9Ki50v zs7S6CdbxipMqulO7el4a4PxHPxqk/GrH5uTkQsSuoSR4JbVpbewQBWOFdsOH6n7xZ+idh qYmTZF1R7oC0Nl9rHfY5m72qdwT22bJbktzI7PaNq/zJBghbZbkvj0+m386uSQ== Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Date: Thu, 02 Apr 2026 13:35:37 +0200 From: Nicolai Buchwitz To: =?UTF-8?Q?Th=C3=A9o_Lebrun?= Cc: Nicolas Ferre , Claudiu Beznea , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Richard Cochran , Russell King , Paolo Valerio , Conor Dooley , Vladimir Kondratiev , Gregory CLEMENT , =?UTF-8?Q?Beno=C3=AEt_Monin?= , Tawfik Bayouk , Thomas Petazzoni , Maxime Chevallier , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next 00/11] net: macb: implement context swapping In-Reply-To: <20260401-macb-context-v1-0-9590c5ab7272@bootlin.com> References: <20260401-macb-context-v1-0-9590c5ab7272@bootlin.com> Message-ID: X-Sender: nb@tipi-net.de Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Last-TLS-Session-Version: TLSv1.3 On 1.4.2026 18:39, Théo Lebrun wrote: > MACB has a pretty primitive approach to buffer management. They are all > stored in `struct macb *bp`. On operations that require buffer realloc > (set_ringparam & change_mtu ATM), the only option is to close the > interface, change our global state and re-open the interface. > > Two issues: > - It doesn't fly on memory pressured systems; we free our precious > buffers and don't manage to reallocate fully, meaning our machine > just lost its network access. > - Anecdotally, it is pretty slow because it implies a full PHY reinit. > > Instead, we shall: > - allocate a new context (including buffers) first > - if it fails, early return without any impact to the interface > - stop interface > - update global state (bp, netdev, etc) > - pass newly allocated buffer pointers to the hardware > - start interface > - free old context > > This is what we implement here. Both .set_ringparam() and > .ndo_change_mtu() are covered by this series. In the future, > at least .set_channels() [0], XDP [1] and XSK [2] would benefit. Thanks for your work, the context swapping approach probably makes a lot of sense and will finally bring proper MTU change support that I tried to patch earlier. > > The change is super intrusive so conflicts will be major. Sorry! > > Thanks, > Have a nice day, > Théo > > [0]: > https://lore.kernel.org/netdev/20260317-macb-set-channels-v4-0-1bd4f4ffcfca@bootlin.com/ > [1]: > https://lore.kernel.org/netdev/20260323221047.2749577-1-pvalerio@redhat.com/ > [2]: > https://lore.kernel.org/netdev/20260304-macb-xsk-v1-0-ba2ebe2bdaa3@bootlin.com/ > > Signed-off-by: Théo Lebrun > --- > Théo Lebrun (11): > net: macb: unify device pointer naming convention > net: macb: unify `struct macb *` naming convention > net: macb: unify queue index variable naming convention and types > net: macb: enforce reverse christmas tree (RCT) convention > net: macb: allocate tieoff descriptor once across device lifetime > net: macb: introduce macb_context struct for buffer management > net: macb: avoid macb_init_rx_buffer_size() modifying state > net: macb: make `struct macb` subset reachable from macb_context > struct > net: macb: introduce macb_context_alloc() helper > net: macb: use context swapping in .set_ringparam() > net: macb: use context swapping in .ndo_change_mtu() > > drivers/net/ethernet/cadence/macb.h | 119 +- > drivers/net/ethernet/cadence/macb_main.c | 1731 > +++++++++++++++++------------- > drivers/net/ethernet/cadence/macb_pci.c | 46 +- > drivers/net/ethernet/cadence/macb_ptp.c | 26 +- > 4 files changed, 1090 insertions(+), 832 deletions(-) > --- > base-commit: 321d1ee521de1362c22adadbc0ce066050a17783 The series didn't apply cleanly on current net-next. The base commit 321d1ee521de doesn't seem to be upstream yet, is this based on your set_channels v4 series? > change-id: 20260401-macb-context-bd0caf20414d > > Best regards, > -- > Théo Lebrun Thanks Nicolai