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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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260101221359.22298-2-frederic@kernel.org> X-Rspamd-Queue-Id: 9D3DF160004 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: miqsd4gqcqrsmxykftg4jccjm5ebe5w6 X-HE-Tag: 1769098461-490331 X-HE-Meta: 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 pCEe3F0i znNcYksimn+wpF4WuvLfdw5SQ2CeBr83dfZJVwFc1FYz2uWRd+TB2UyRRsfYkfmBY4MsLkxrvnO1yTX8JGBWDMBCynsHSZWCHWuidoKjaGCegIifUbw/rY9ElcTKx0iTfoIGOZfg81oexA1RlkBLI0mCspf/P9qgmP3ObhzjSZKZsWh5F7opWg+cbI9X64WxbLzPSXg8pT1IlTKvZQX3SNvO+w9x9SHM1sh7GxDfFVmrBLU1GG9WR0rsL2V2YTOUeyQFn7zsYh1sF6egXlZDriY1gsdiR571hzhSfjAgYFowZstg= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 >