On Thu, Aug 23, 2012 at 3:35 PM, Tejun Heo <tj@xxxxxxxxxx> wrote:
> pci_call_probe() uses work_on_cpu(), which creates and tears down a
> full kthread on each call, to invoke ->probe() on node local CPU for
> allocation affinity.
>
> The same goal can easily be achieved using a work item. This patch
> rewrites pci_call_probe() so that it uses a work item instead of
> work_on_cpu().
>
> Note that the function is restructured for simplicity. This adds
> get/put_online_cpus() pair for devices without node but the overhead
> of doing so isn't anything material at this level.
>
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
I applied this to my "next" branch and pushed it. Thanks!
> ---
> I tested both paths but had to simulate device on foreign node.
>
> Thanks.
>
> drivers/pci/pci-driver.c | 48 +++++++++++++++++++++++++++--------------------
> 1 file changed, 28 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
> index 5270f1a..554c15a 100644
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
> @@ -274,11 +274,14 @@ struct drv_dev_and_id {
> struct pci_driver *drv;
> struct pci_dev *dev;
> const struct pci_device_id *id;
> + struct work_struct work;
> + int error;
> };
>
> -static long local_pci_probe(void *_ddi)
> +static void pci_probe_fn(struct work_struct *work)
> {
> - struct drv_dev_and_id *ddi = _ddi;
> + struct drv_dev_and_id *ddi = container_of(work, struct drv_dev_and_id,
> + work);
> struct device *dev = &ddi->dev->dev;
> int rc;
>
> @@ -298,33 +301,38 @@ static long local_pci_probe(void *_ddi)
> pm_runtime_set_suspended(dev);
> pm_runtime_put_noidle(dev);
> }
> - return rc;
> +
> + ddi->error = rc;
> }
>
> static int pci_call_probe(struct pci_driver *drv, struct pci_dev *dev,
> const struct pci_device_id *id)
> {
> - int error, node;
> + int node;
> + int cpu = nr_cpu_ids;
> struct drv_dev_and_id ddi = { drv, dev, id };
>
> - /* Execute driver initialization on node where the device's
> - bus is attached to. This way the driver likely allocates
> - its local memory on the right node without any need to
> - change it. */
> - node = dev_to_node(&dev->dev);
> - if (node >= 0) {
> - int cpu;
> + /*
> + * Execute driver initialization on node where the device's bus is
> + * attached to. This way the driver likely allocates its local
> + * memory on the right node without any need to change it.
> + */
> + get_online_cpus();
>
> - get_online_cpus();
> + node = dev_to_node(&dev->dev);
> + if (node >= 0)
> cpu = cpumask_any_and(cpumask_of_node(node), cpu_online_mask);
> - if (cpu < nr_cpu_ids)
> - error = work_on_cpu(cpu, local_pci_probe, &ddi);
> - else
> - error = local_pci_probe(&ddi);
> - put_online_cpus();
> - } else
> - error = local_pci_probe(&ddi);
> - return error;
> +
> + if (cpu < nr_cpu_ids) {
> + INIT_WORK_ONSTACK(&ddi.work, pci_probe_fn);
> + schedule_work_on(cpu, &ddi.work);
> + flush_work(&ddi.work);
> + } else {
> + pci_probe_fn(&ddi.work);
> + }
> +
> + put_online_cpus();
> + return ddi.error;
> }
>
> /**
--
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