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Date: Tue, 2 Apr 2019 03:40:06 -0700
From: tip-bot for Josh Poimboeuf <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: aarcange@...hat.com, hpa@...or.com, tglx@...utronix.de,
jpoimboe@...hat.com, mingo@...nel.org, jikos@...nel.org,
peterz@...radead.org, linux-kernel@...r.kernel.org,
longman@...hat.com
Subject: [tip:smp/hotplug] cpu/hotplug: Create SMT sysfs interface for all
arches
Commit-ID: de7b77e5bb9451417ca57f1b6501da654587c048
Gitweb: https://git.kernel.org/tip/de7b77e5bb9451417ca57f1b6501da654587c048
Author: Josh Poimboeuf <jpoimboe@...hat.com>
AuthorDate: Wed, 27 Mar 2019 07:00:29 -0500
Committer: Thomas Gleixner <tglx@...utronix.de>
CommitDate: Tue, 2 Apr 2019 12:36:56 +0200
cpu/hotplug: Create SMT sysfs interface for all arches
Make the /sys/devices/system/cpu/smt/* files available on all arches, so
user space has a consistent way to detect whether SMT is enabled.
The 'control' file now shows 'notimplemented' for architectures which
don't yet have CONFIG_HOTPLUG_SMT.
[ tglx: Make notimplemented a real state ]
Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Andrea Arcangeli <aarcange@...hat.com>
Cc: Waiman Long <longman@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Jiri Kosina <jikos@...nel.org>
Link: https://lkml.kernel.org/r/469c2b98055f2c41e75748e06447d592a64080c9.1553635520.git.jpoimboe@redhat.com
---
Documentation/ABI/testing/sysfs-devices-system-cpu | 10 ++--
include/linux/cpu.h | 3 +-
kernel/cpu.c | 64 +++++++++++++---------
3 files changed, 47 insertions(+), 30 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index 9605dbd4b5b5..5eea46fefcb2 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -511,10 +511,12 @@ Description: Control Symetric Multi Threading (SMT)
control: Read/write interface to control SMT. Possible
values:
- "on" SMT is enabled
- "off" SMT is disabled
- "forceoff" SMT is force disabled. Cannot be changed.
- "notsupported" SMT is not supported by the CPU
+ "on" SMT is enabled
+ "off" SMT is disabled
+ "forceoff" SMT is force disabled. Cannot be changed.
+ "notsupported" SMT is not supported by the CPU
+ "notimplemented" SMT runtime toggling is not
+ implemented for the architecture
If control status is "forceoff" or "notsupported" writes
are rejected.
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 5041357d0297..ae99dde02320 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -175,6 +175,7 @@ enum cpuhp_smt_control {
CPU_SMT_DISABLED,
CPU_SMT_FORCE_DISABLED,
CPU_SMT_NOT_SUPPORTED,
+ CPU_SMT_NOT_IMPLEMENTED,
};
#if defined(CONFIG_SMP) && defined(CONFIG_HOTPLUG_SMT)
@@ -182,7 +183,7 @@ extern enum cpuhp_smt_control cpu_smt_control;
extern void cpu_smt_disable(bool force);
extern void cpu_smt_check_topology(void);
#else
-# define cpu_smt_control (CPU_SMT_ENABLED)
+# define cpu_smt_control (CPU_SMT_NOT_IMPLEMENTED)
static inline void cpu_smt_disable(bool force) { }
static inline void cpu_smt_check_topology(void) { }
#endif
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 6754f3ecfd94..b8bf3f93e39b 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -2033,19 +2033,6 @@ static const struct attribute_group cpuhp_cpu_root_attr_group = {
#ifdef CONFIG_HOTPLUG_SMT
-static const char *smt_states[] = {
- [CPU_SMT_ENABLED] = "on",
- [CPU_SMT_DISABLED] = "off",
- [CPU_SMT_FORCE_DISABLED] = "forceoff",
- [CPU_SMT_NOT_SUPPORTED] = "notsupported",
-};
-
-static ssize_t
-show_smt_control(struct device *dev, struct device_attribute *attr, char *buf)
-{
- return snprintf(buf, PAGE_SIZE - 2, "%s\n", smt_states[cpu_smt_control]);
-}
-
static void cpuhp_offline_cpu_device(unsigned int cpu)
{
struct device *dev = get_cpu_device(cpu);
@@ -2116,9 +2103,10 @@ static int cpuhp_smt_enable(void)
return ret;
}
+
static ssize_t
-store_smt_control(struct device *dev, struct device_attribute *attr,
- const char *buf, size_t count)
+__store_smt_control(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
{
int ctrlval, ret;
@@ -2156,14 +2144,44 @@ store_smt_control(struct device *dev, struct device_attribute *attr,
unlock_device_hotplug();
return ret ? ret : count;
}
+
+#else /* !CONFIG_HOTPLUG_SMT */
+static ssize_t
+__store_smt_control(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ return -ENODEV;
+}
+#endif /* CONFIG_HOTPLUG_SMT */
+
+static const char *smt_states[] = {
+ [CPU_SMT_ENABLED] = "on",
+ [CPU_SMT_DISABLED] = "off",
+ [CPU_SMT_FORCE_DISABLED] = "forceoff",
+ [CPU_SMT_NOT_SUPPORTED] = "notsupported",
+ [CPU_SMT_NOT_IMPLEMENTED] = "notimplemented",
+};
+
+static ssize_t
+show_smt_control(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ const char *state = smt_states[cpu_smt_control];
+
+ return snprintf(buf, PAGE_SIZE - 2, "%s\n", state);
+}
+
+static ssize_t
+store_smt_control(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ return __store_smt_control(dev, attr, buf, count);
+}
static DEVICE_ATTR(control, 0644, show_smt_control, store_smt_control);
static ssize_t
show_smt_active(struct device *dev, struct device_attribute *attr, char *buf)
{
- bool active = topology_max_smt_threads() > 1;
-
- return snprintf(buf, PAGE_SIZE - 2, "%d\n", active);
+ return snprintf(buf, PAGE_SIZE - 2, "%d\n", sched_smt_active());
}
static DEVICE_ATTR(active, 0444, show_smt_active, NULL);
@@ -2179,21 +2197,17 @@ static const struct attribute_group cpuhp_smt_attr_group = {
NULL
};
-static int __init cpu_smt_state_init(void)
+static int __init cpu_smt_sysfs_init(void)
{
return sysfs_create_group(&cpu_subsys.dev_root->kobj,
&cpuhp_smt_attr_group);
}
-#else
-static inline int cpu_smt_state_init(void) { return 0; }
-#endif
-
static int __init cpuhp_sysfs_init(void)
{
int cpu, ret;
- ret = cpu_smt_state_init();
+ ret = cpu_smt_sysfs_init();
if (ret)
return ret;
@@ -2214,7 +2228,7 @@ static int __init cpuhp_sysfs_init(void)
return 0;
}
device_initcall(cpuhp_sysfs_init);
-#endif
+#endif /* CONFIG_SYSFS && CONFIG_HOTPLUG_CPU */
/*
* cpu_bit_bitmap[] is a special, "compressed" data structure that
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