Re: [PATCH 01/33] PCI: Prepare to protect against concurrent isolated cpuset change

Frederic Weisbecker
2025-12-30T22:38:13Z

Le Mon, Dec 29, 2025 at 11:23:56AM +0800, Zhang Qiao a écrit :
> Hi, Weisbecker，
>
> 在 2025/12/24 21:44, Frederic Weisbecker 写道:
> > 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 <frederic@kernel.org>
> > ---
> > 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..786d6ce40999 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 };
> > +
> > + INIT_WORK_ONSTACK(&arg.work, local_pci_probe_callback);
> >
> > if (!zalloc_cpumask_var(&wq_domain_mask, GFP_KERNEL)) {
> > error = -ENOMEM;
>
> If we return from here, arg.work will not be destroyed.

Good catch! Thanks.

--
Frederic Weisbecker
SUSE Labs