Re: [Patch v1 2/3] PCI: prevent work_on_cpu's probe to execute on isolated CPUs
From: Frederic Weisbecker <frederic@kernel.org>
Date: 2020-06-16 23:22:22
Also in:
linux-pci, lkml
On Wed, Jun 10, 2020 at 12:12:25PM -0400, Nitesh Narayan Lal wrote:
quoted hunk ↗ jump to hunk
From: Alex Belits <redacted> 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 Physical device. This patch replaces 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 <redacted> Signed-off-by: Nitesh Narayan Lal <redacted> --- drivers/pci/pci-driver.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)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, 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));
Looks like cpumask_of_node() is based on online CPUs. So that all looks good. Thanks! Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
if (cpu < nr_cpu_ids) error = work_on_cpu(cpu, local_pci_probe, &ddi); -- 2.18.4