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 D42B03DE340; Thu, 22 Jan 2026 16:14:22 +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=1769098463; cv=none; b=mB5D3nwgyHHL9U4miCi05ONpoiV6eiZyaed5xJAtHqcHsMSNTFaxVEPcyK7wj82CZn3UIzZD746A5XFOZbvyEDL6MpbCFJBODQV60+HpSxazuwhr5/QI3cTVLhNzWgpOBHcAa3SKKnXf7TvtK/HKzLzR/Iy/IQ8pbqXNcGsJbeg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769098463; c=relaxed/simple; bh=A5voT2wLi+tc3Gakd2qWcqijnaOQacYQLsQbIZzWGuI=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=hEIWQXLdjb+vFM7PenVjPy1f98q0/qXIxH1lt4poq7GOb6m26Yn2t1MxFU4E5iuumF9CRyyLSf2B5t3KUUMunx3y3eHDRVhP/xUvnjyQ9IvweUm4fcl9Qgq8/PorbXRnoTyxsRCHNqWTp6RzOIq8XiVPB6wOe7gFk4/z9E/P9Wg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=X+jvMFsn; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="X+jvMFsn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7278DC116C6; Thu, 22 Jan 2026 16:14:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769098460; bh=A5voT2wLi+tc3Gakd2qWcqijnaOQacYQLsQbIZzWGuI=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=X+jvMFsnwbGFZzHk62uEp/xLYGy0TYh1BIiuZyuFCQ4UZ9wozDqF1y/yWLjDQKGsL yEnv1WPUWCjDLjL8UokP67Qh7t0Dwu0gx0fQqEVC7OA/HoPzeG089LVSShsv/cRJoy 8SeSVI0sRtha8f79da2Vhu6ZmhHHjFaQ7jpDBY3PBFxm4iROWN5UY8RiYnBZCQG09j /0PFfUXflZlk6cv6CFsBKaFBN5q7svB1GokuAdYu/1v5upDzifmEVtnp7qWbstMBah a7EsJ4SDWzUCc4gUvWoG3Uvcbej3aRo8l+/FAuo8FDR6yV76kFXawp+1BOd8Y6jOVt PuCYYsJIAfXVw== Date: Thu, 22 Jan 2026 10:14:19 -0600 From: Bjorn Helgaas To: Frederic Weisbecker Cc: LKML , Michal =?utf-8?Q?Koutn=C3=BD?= , Andrew Morton , Bjorn Helgaas , Catalin Marinas , Chen Ridong , Danilo Krummrich , "David S . Miller" , Eric Dumazet , Gabriele Monaco , Greg Kroah-Hartman , Ingo Molnar , Jakub Kicinski , Jens Axboe , Johannes Weiner , Lai Jiangshan , Marco Crivellari , Michal Hocko , Muchun Song , Paolo Abeni , Peter Zijlstra , Phil Auld , "Rafael J . Wysocki" , Roman Gushchin , Shakeel Butt , Simon Horman , Tejun Heo , Thomas Gleixner , Vlastimil Babka , Waiman Long , Will Deacon , cgroups@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-block@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [PATCH 01/33] PCI: Prepare to protect against concurrent isolated cpuset change Message-ID: <20260122161419.GA1250200@bhelgaas> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260101221359.22298-2-frederic@kernel.org> On Thu, Jan 01, 2026 at 11:13:26PM +0100, Frederic Weisbecker wrote: > HK_TYPE_DOMAIN will soon integrate cpuset isolated partitions and > therefore be made modifiable at runtime. Synchronize against the cpumask > update using RCU. > > The RCU locked section includes both the housekeeping CPU target > election for the PCI probe work and the work enqueue. > > This way the housekeeping update side will simply need to flush the > pending related works after updating the housekeeping mask in order to > make sure that no PCI work ever executes on an isolated CPU. This part > will be handled in a subsequent patch. > > Signed-off-by: Frederic Weisbecker Acked-by: Bjorn Helgaas > --- > drivers/pci/pci-driver.c | 47 ++++++++++++++++++++++++++++++++-------- > 1 file changed, 38 insertions(+), 9 deletions(-) > > diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c > index 7c2d9d596258..a6111140755c 100644 > --- a/drivers/pci/pci-driver.c > +++ b/drivers/pci/pci-driver.c > @@ -302,9 +302,8 @@ struct drv_dev_and_id { > const struct pci_device_id *id; > }; > > -static long local_pci_probe(void *_ddi) > +static int local_pci_probe(struct drv_dev_and_id *ddi) > { > - struct drv_dev_and_id *ddi = _ddi; > struct pci_dev *pci_dev = ddi->dev; > struct pci_driver *pci_drv = ddi->drv; > struct device *dev = &pci_dev->dev; > @@ -338,6 +337,19 @@ static long local_pci_probe(void *_ddi) > return 0; > } > > +struct pci_probe_arg { > + struct drv_dev_and_id *ddi; > + struct work_struct work; > + int ret; > +}; > + > +static void local_pci_probe_callback(struct work_struct *work) > +{ > + struct pci_probe_arg *arg = container_of(work, struct pci_probe_arg, work); > + > + arg->ret = local_pci_probe(arg->ddi); > +} > + > static bool pci_physfn_is_probed(struct pci_dev *dev) > { > #ifdef CONFIG_PCI_IOV > @@ -362,34 +374,51 @@ static int pci_call_probe(struct pci_driver *drv, struct pci_dev *dev, > dev->is_probed = 1; > > cpu_hotplug_disable(); > - > /* > * Prevent nesting work_on_cpu() for the case where a Virtual Function > * device is probed from work_on_cpu() of the Physical device. > */ > if (node < 0 || node >= MAX_NUMNODES || !node_online(node) || > pci_physfn_is_probed(dev)) { > - cpu = nr_cpu_ids; > + error = local_pci_probe(&ddi); > } else { > cpumask_var_t wq_domain_mask; > + struct pci_probe_arg arg = { .ddi = &ddi }; > > if (!zalloc_cpumask_var(&wq_domain_mask, GFP_KERNEL)) { > error = -ENOMEM; > goto out; > } > + > + INIT_WORK_ONSTACK(&arg.work, local_pci_probe_callback); > + > + /* > + * The target election and the enqueue of the work must be within > + * the same RCU read side section so that when the workqueue pool > + * is flushed after a housekeeping cpumask update, further readers > + * are guaranteed to queue the probing work to the appropriate > + * targets. > + */ > + rcu_read_lock(); > cpumask_and(wq_domain_mask, > housekeeping_cpumask(HK_TYPE_WQ), > housekeeping_cpumask(HK_TYPE_DOMAIN)); > > cpu = cpumask_any_and(cpumask_of_node(node), > wq_domain_mask); > + if (cpu < nr_cpu_ids) { > + schedule_work_on(cpu, &arg.work); > + rcu_read_unlock(); > + flush_work(&arg.work); > + error = arg.ret; > + } else { > + rcu_read_unlock(); > + error = local_pci_probe(&ddi); > + } > + > free_cpumask_var(wq_domain_mask); > + destroy_work_on_stack(&arg.work); > } > - > - if (cpu < nr_cpu_ids) > - error = work_on_cpu(cpu, local_pci_probe, &ddi); > - else > - error = local_pci_probe(&ddi); > out: > dev->is_probed = 0; > cpu_hotplug_enable(); > -- > 2.51.1 >