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 BAE3820EA35; Tue, 12 Nov 2024 16:53:50 +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=1731430431; cv=none; b=GgmjNDFhSNMHcnVBRP4z26fwrgMPUgKoVe0OBmTysRpufAqedHiTXvXxlL7WOOAbNKjyFokol4SC9yOGig1LRNThNb5SvnXZsELkB9iX6/Ib0wmUKSO7taMJeBAe6so+/Hx7KkhxJhgkhIsj+Wlo/La34hTXJnlE4MML9aajrB4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731430431; c=relaxed/simple; bh=ODw1HrrVUx4XDdn+NA3ZiM07EdzE1pUd7SlEHngh474=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ld58Ybm/MAHieV267qpQSdC8nH1xbEtDduRvA4FZTQnDFY1AaRHLd0cMtHCSp2VZp4N4HPGVjd0drzkHsUceKTSJncr5+C1/7gcopjtmeQiOJDYf3z41gdpHOFMQKZqL6RrqEE6hiWuDxTcu2hdtcB4USdWPbGClW6hkp4AZGgg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=YPpko2qb; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="YPpko2qb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 71BF8C4CECD; Tue, 12 Nov 2024 16:53:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1731430430; bh=ODw1HrrVUx4XDdn+NA3ZiM07EdzE1pUd7SlEHngh474=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=YPpko2qbSkx3B/Yke7goINBZ5S4Gf38HLGrkUd18K0+NDW5TDc2VM8SjUAEi81sCE VWJR7e47xV/EaMi8Ut+FCVeSu/Se2MCM1NoE5AuqTmi3OjltsAR34taDLR9bK7barr x0PRbnboZ7eYnBg6m7u87Mtvx+l0Csa6qtyBnsc0= Date: Tue, 12 Nov 2024 17:53:47 +0100 From: Greg Kroah-Hartman To: Daniel Wagner Cc: Daniel Wagner , Jens Axboe , Bjorn Helgaas , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , Eugenio =?iso-8859-1?Q?P=E9rez?= , "Martin K. Petersen" , Keith Busch , Christoph Hellwig , Sagi Grimberg , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, virtualization@lists.linux.dev, linux-scsi@vger.kernel.org, megaraidlinux.pdl@broadcom.com, mpi3mr-linuxdrv.pdl@broadcom.com, MPT-FusionLinux.pdl@broadcom.com, storagedev@microchip.com, linux-nvme@lists.infradead.org Subject: Re: [PATCH v3 4/8] blk-mp: introduce blk_mq_hctx_map_queues Message-ID: <2024111212-rash-suffocate-dc13@gregkh> References: <20241112-refactor-blk-affinity-helpers-v3-0-573bfca0cbd8@kernel.org> <20241112-refactor-blk-affinity-helpers-v3-4-573bfca0cbd8@kernel.org> <2024111202-parish-prowess-78bc@gregkh> <2024111215-jury-unlighted-3953@gregkh> <5967d256-037e-4ac8-a509-c6955b03db05@flourine.local> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5967d256-037e-4ac8-a509-c6955b03db05@flourine.local> On Tue, Nov 12, 2024 at 05:15:31PM +0100, Daniel Wagner wrote: > On Tue, Nov 12, 2024 at 04:42:40PM +0100, Greg Kroah-Hartman wrote: > > On Tue, Nov 12, 2024 at 04:33:09PM +0100, Daniel Wagner wrote: > > > On Tue, Nov 12, 2024 at 02:58:43PM +0100, Greg Kroah-Hartman wrote: > > > > > +void blk_mq_hctx_map_queues(struct blk_mq_queue_map *qmap, > > > > > + struct device *dev, unsigned int offset) > > > > > + > > > > > +{ > > > > > + const struct cpumask *mask; > > > > > + unsigned int queue, cpu; > > > > > + > > > > > + if (!dev->bus->irq_get_affinity) > > > > > + goto fallback; > > > > > > > > I think this is better than hard-coding it, but are you sure that the > > > > bus will always be bound to the device here so that you have a valid > > > > bus-> pointer? > > > > > > No, I just assumed the bus pointer is always valid. If it is possible to > > > have a device without a bus, than I'll better extend the condition to > > > > > > if (!dev->bus || !dev->bus->irq_get_affinity) > > > goto fallback; > > > > I don't know if it's possible as I don't know what codepaths are calling > > this, it was hard to unwind. But you should check "just to be safe" :) > > The main path to map_queues is via the probe functions. There are some > more paths like when updating a tagset after the number of queues but > that is all after the probe function. > > nvme_probe > nvme_alloc_admin_tag_set > blk_mq_alloc_tag_set > blk_mq_update_queue_map > set->ops->map_queues > blk_mq_htcx_map_queues > nvme_alloc_io_tag_set > blk_mq_alloc_tag_set > blk_mq_update_queue_map > set->ops->map_queues > blk_mq_htcx_map_queues > > virtscsi_probe, hisi_sas_v3_probe, ... > scsi_add_host > scsi_add_host_with_dma > scsi_mq_setup_tags > blk_mq_alloc_tag_set > blk_mq_update_queue_map > set->ops->map_queues > blk_mq_htcx_map_queues > > virtblk_probe > blk_mq_alloc_tag_set > blk_mq_update_queue_map > set->ops->map_queues > blk_mq_htcx_map_queues > > Does this help? Ok, that seems fine. Worst case, you crash and it's obvious that it needs to be checked in the future :) thanks, greg k-h