From de7b77e5bb9451417ca57f1b6501da654587c048 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Wed, 27 Mar 2019 07:00:29 -0500 Subject: 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 Signed-off-by: Thomas Gleixner Cc: Andrea Arcangeli Cc: Waiman Long Cc: Peter Zijlstra Cc: Jiri Kosina Link: https://lkml.kernel.org/r/469c2b98055f2c41e75748e06447d592a64080c9.1553635520.git.jpoimboe@redhat.com --- kernel/cpu.c | 64 ++++++++++++++++++++++++++++++++++++------------------------ 1 file changed, 39 insertions(+), 25 deletions(-) (limited to 'kernel') 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 -- cgit v1.2.3