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 <t...@kernel.org>
---
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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