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[v2,2/3] PCI: Restrict probe functions to housekeeping CPUs

Message ID 20200622234510.240834-3-nitesh@redhat.com
State New
Headers show
Series Preventing job distribution to isolated CPUs | expand

Commit Message

Nitesh Narayan Lal June 22, 2020, 11:45 p.m. UTC
From: Alex Belits <abelits@marvell.com>

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>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
 drivers/pci/pci-driver.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
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diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index da6510af1221..449466f71040 100644
--- 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,
 		cpu = nr_cpu_ids;
-		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);