PCI: Restrict probe functions to housekeeping CPUs

pci_call_probe() prevents the nesting of work_on_cpu() for a scenario
where a VF device is probed from work_on_cpu() of the PF.

Replace the cpumask used in pci_call_probe() from all online CPUs to only
housekeeping CPUs. This is to ensure that there are no additional latency
overheads caused due to the pinning of jobs on isolated CPUs.

Signed-off-by: Alex Belits <abelits@marvell.com>
Signed-off-by: Nitesh Narayan Lal <nitesh@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lkml.kernel.org/r/20200625223443.2684-3-nitesh@redhat.com

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index da6510af12214af1dac6c93edc02a9a68eba67a5..449466f71040d22e0709800862fc170c66904c52 100644 (file)
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -12,6 +12,7 @@
 #include <linux/string.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
+#include <linux/sched/isolation.h>
 #include <linux/cpu.h>
 #include <linux/pm_runtime.h>
 #include <linux/suspend.h>
@@ -333,6 +334,7 @@ static int pci_call_probe(struct pci_driver *drv, struct pci_dev *dev,
                          const struct pci_device_id *id)
 {
        int error, node, cpu;
+       int hk_flags = HK_FLAG_DOMAIN | HK_FLAG_WQ;
        struct drv_dev_and_id ddi = { drv, dev, id };
 
        /*
@@ -353,7 +355,8 @@ static int pci_call_probe(struct pci_driver *drv, struct pci_dev *dev,
            pci_physfn_is_probed(dev))
                cpu = nr_cpu_ids;
        else
-               cpu = cpumask_any_and(cpumask_of_node(node), cpu_online_mask);
+               cpu = cpumask_any_and(cpumask_of_node(node),
+                                     housekeeping_cpumask(hk_flags));
 
        if (cpu < nr_cpu_ids)
                error = work_on_cpu(cpu, local_pci_probe, &ddi);