linux-kernel - [PATCH 1/8] pci: Decouple HK_FLAG_WQ and HK_FLAG

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Date:   Fri,  4 Feb 2022 14:04:26 +0100
From:   Frederic Weisbecker <frederic@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Tejun Heo <tj@...nel.org>, Christoph Lameter <cl@...two.de>,
        Juri Lelli <juri.lelli@...hat.com>,
        Alex Belits <abelits@...vell.com>,
        Nitesh Lal <nilal@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Paul Gortmaker <paul.gortmaker@...driver.com>,
        Nicolas Saenz <nsaenzju@...hat.com>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Phil Auld <pauld@...hat.com>,
        Marcelo Tosatti <mtosatti@...hat.com>,
        Zefan Li <lizefan.x@...edance.com>
Subject: [PATCH 1/8] pci: Decouple HK_FLAG_WQ and HK_FLAG_DOMAIN cpumask fetch

To prepare for supporting each feature of the housekeeping cpumask
toward cpuset, prepare each of the HK_FLAG_* entries to move to their
own cpumask with enforcing to fetch them individually. The new
constraint is that multiple HK_FLAG_* entries can't be mixed together
anymore in a single call to housekeeping cpumask().

This will later allow, for example, to runtime modify the cpulist passed
through "isolcpus=", "nohz_full=" and "rcu_nocbs=" kernel boot
parameters.

Reviewed-by: Juri Lelli <juri.lelli@...hat.com>
Reviewed-by: Phil Auld <pauld@...hat.com>
Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Juri Lelli <juri.lelli@...hat.com>
Cc: Marcelo Tosatti <mtosatti@...hat.com>
Cc: Nitesh Lal <nilal@...hat.com>
Cc: Nicolas Saenz <nsaenzju@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Christoph Lameter <cl@...two.de>
Cc: Tejun Heo <tj@...nel.org>
Cc: Zefan Li <lizefan.x@...edance.com>
Cc: Alex Belits <abelits@...vell.com>
Cc: Paul Gortmaker <paul.gortmaker@...driver.com>
Cc: Paul E. McKenney  <paulmck@...nel.org>
---
 drivers/pci/pci-driver.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 588588cfda48..4a5792c82d08 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -350,7 +350,6 @@ 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 };
 
 	/*
@@ -368,17 +367,29 @@ static int pci_call_probe(struct pci_driver *drv, struct pci_dev *dev,
 	 * 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))
+	    pci_physfn_is_probed(dev)) {
 		cpu = nr_cpu_ids;
-	else
+	} else {
+		cpumask_var_t wq_domain_mask;
+
+		if (!zalloc_cpumask_var(&wq_domain_mask, GFP_KERNEL)) {
+			error = -ENOMEM;
+			goto out;
+		}
+		cpumask_and(wq_domain_mask,
+			    housekeeping_cpumask(HK_FLAG_WQ),
+			    housekeeping_cpumask(HK_FLAG_DOMAIN));
+
 		cpu = cpumask_any_and(cpumask_of_node(node),
-				      housekeeping_cpumask(hk_flags));
+				      wq_domain_mask);
+		free_cpumask_var(wq_domain_mask);
+	}
 
 	if (cpu < nr_cpu_ids)
 		error = work_on_cpu(cpu, local_pci_probe, &ddi);
 	else
 		error = local_pci_probe(&ddi);
-
+out:
 	dev->is_probed = 0;
 	cpu_hotplug_enable();
 	return error;
-- 
2.25.1