From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 25 Oct 2018 15:52:13 -0600 From: Keith Busch To: Jens Axboe Cc: linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, Thomas Gleixner , linux-kernel@vger.kernel.org Subject: Re: [PATCH 11/14] irq: add support for allocating (and affinitizing) sets of IRQs Message-ID: <20181025215213.GA8141@localhost.localdomain> References: <20181025211626.12692-1-axboe@kernel.dk> <20181025211626.12692-12-axboe@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20181025211626.12692-12-axboe@kernel.dk> List-ID: On Thu, Oct 25, 2018 at 03:16:23PM -0600, Jens Axboe wrote: > A driver may have a need to allocate multiple sets of MSI/MSI-X > interrupts, and have them appropriately affinitized. Add support for > defining a number of sets in the irq_affinity structure, of varying > sizes, and get each set affinitized correctly across the machine. <> > @@ -258,13 +272,18 @@ int irq_calc_affinity_vectors(int minvec, int maxvec, const struct irq_affinity > { > int resv = affd->pre_vectors + affd->post_vectors; > int vecs = maxvec - resv; > + int i, set_vecs; > int ret; > > if (resv > minvec) > return 0; > > get_online_cpus(); > - ret = min_t(int, cpumask_weight(cpu_possible_mask), vecs) + resv; > + ret = min_t(int, cpumask_weight(cpu_possible_mask), vecs); > put_online_cpus(); > - return ret; > + > + for (i = 0, set_vecs = 0; i < affd->nr_sets; i++) > + set_vecs += affd->sets[i]; > + > + return resv + max(ret, set_vecs); > } This is looking pretty good, but we may risk getting into an infinite loop in __pci_enable_msix_range() if we're requesting too many vectors in a set: the above code may continue returning set_vecs, overriding the reduced nvec that pci requested, and pci msix initialization will continue to fail because it is repeatedly requesting to activate the same vector count that failed before.