lkml.org 
[lkml]   [2020]   [Jan]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
SubjectRE: [PATCH v2] cpu-topology: Skip the exist but not possible cpu nodes
Date
> -----Original Message-----
> From: Sudeep Holla [mailto:sudeep.holla@arm.com]
> Sent: Tuesday, January 14, 2020 6:30 PM
> To: Zengtao (B)
> Cc: Linuxarm; Greg Kroah-Hartman; Rafael J. Wysocki;
> linux-kernel@vger.kernel.org; Sudeep Holla
> Subject: Re: [PATCH v2] cpu-topology: Skip the exist but not possible cpu
> nodes
>
> On Tue, Jan 14, 2020 at 01:42:25AM +0000, Zengtao (B) wrote:
> > Could you help to explain here?
> > I understand there are two abnormal cases:
> > 1. The cpu node exist in the device tree, but not a possible cpu.
> > This case can be caught by of_cpu_node_to_id's return value.
>
> Yes if of_cpu_node_to_id returns -ENODEV, it means there's no logical
> CPU associated with this DT node.
>
> > 2. The cpu node does not exist. This case can be caught by above logic.
> Or
> > do you think of_parse_phandle's return value is enough?
>
> Again yes, there's nothing extra needed.
>
> The only change you need is to consider -ENODEV while handling the
> case(1)
>
Thanks very much for your explanation.
So finally it turns into a very simple patch like this, more cleaner:
+/*
+ * This function returns the logic cpu number of the node.
+ * There are basically three kinds of return values:
+ * (1) logic cpu number which is > 0.
+ * (2) -ENDEV when the node is valid one which can be found in the device tree
+ * but there is no possible cpu nodes to match, when the CONFIG_NR_CPUS is
+ * smaller than cpus node numbers in device tree, this will happen. It's
+ * suggested to just ignore this case.
+ * (3) -1 if the node does not exist in the device tree
+ */
static int __init get_cpu_for_node(struct device_node *node)
{
struct device_node *cpu_node;
@@ -261,7 +271,8 @@ static int __init get_cpu_for_node(struct device_node *node)
if (cpu >= 0)
topology_parse_cpu_capacity(cpu_node, cpu);
else
- pr_crit("Unable to find CPU node for %pOF\n", cpu_node);
+ pr_info("CPU node for %pOF exist but the possible cpu range is :%*pbl\n",
+ cpu_node, cpumask_pr_args(cpu_possible_mask));

of_node_put(cpu_node);
return cpu;
@@ -286,9 +297,8 @@ static int __init parse_core(struct device_node *core, int package_id,
cpu_topology[cpu].package_id = package_id;
cpu_topology[cpu].core_id = core_id;
cpu_topology[cpu].thread_id = i;
- } else {
- pr_err("%pOF: Can't get CPU for thread\n",
- t);
+ } else if (cpu != -ENODEV) {
+ pr_err("%pOF: Can't get CPU for thread\n", t);
of_node_put(t);
return -EINVAL;
}
@@ -307,7 +317,7 @@ static int __init parse_core(struct device_node *core, int package_id,

cpu_topology[cpu].package_id = package_id;
cpu_topology[cpu].core_id = core_id;
- } else if (leaf) {
+ } else if (leaf && cpu != -ENODEV) {
pr_err("%pOF: Can't get CPU for leaf core\n", core);
return -EINVAL;
}
Any more suggestions?

Regards
Zengtao

\
 
 \ /
  Last update: 2020-01-14 13:18    [W:0.047 / U:7.464 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site