From 2c4dcd7fd57b20a21b65da04d89c38a7217d79cf Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Mon, 29 Nov 2021 14:03:07 +0100 Subject: [PATCH] topology/sysfs: export die attributes only if an architectures has support The die_id and die_cpus topology sysfs attributes have been added with commit 0e344d8c709f ("cpu/topology: Export die_id") and commit 2e4c54dac7b3 ("topology: Create core_cpus and die_cpus sysfs attributes"). While they are currently only used and useful for x86 they are still present with bogus default values for all architectures. Instead of enforcing such new sysfs attributes to all architectures, make them only optional visible if an architecture opts in by defining both the topology_die_id and topology_die_cpumask attributes. This is similar to what was done when the book and drawer topology levels were introduced: avoid useless and therefore confusing sysfs attributes for architectures which cannot make use of them. This should not break any existing applications, since this is a rather new interface and applications should be able to handle also older kernel versions without such attributes - besides that they contain only useful information for x86. Acked-by: Peter Zijlstra (Intel) Signed-off-by: Heiko Carstens Link: https://lore.kernel.org/r/20211129130309.3256168-2-hca@linux.ibm.com Signed-off-by: Greg Kroah-Hartman --- Documentation/admin-guide/cputopology.rst | 3 +++ drivers/base/topology.c | 8 ++++++++ include/linux/topology.h | 4 ++++ 3 files changed, 15 insertions(+) diff --git a/Documentation/admin-guide/cputopology.rst b/Documentation/admin-guide/cputopology.rst index 6b62e18..c68d075 100644 --- a/Documentation/admin-guide/cputopology.rst +++ b/Documentation/admin-guide/cputopology.rst @@ -11,6 +11,9 @@ Architecture-neutral, drivers/base/topology.c, exports these attributes. However, the book and drawer related sysfs files will only be created if CONFIG_SCHED_BOOK and CONFIG_SCHED_DRAWER are selected, respectively. +The die hierarchy related sysfs files will only be created if an architecture +provides the related macros as described below. + CONFIG_SCHED_BOOK and CONFIG_SCHED_DRAWER are currently only used on s390, where they reflect the cpu and cache hierarchy. diff --git a/drivers/base/topology.c b/drivers/base/topology.c index 8f2b641..f079a55 100644 --- a/drivers/base/topology.c +++ b/drivers/base/topology.c @@ -45,8 +45,10 @@ static ssize_t name##_list_read(struct file *file, struct kobject *kobj, \ define_id_show_func(physical_package_id); static DEVICE_ATTR_RO(physical_package_id); +#ifdef TOPOLOGY_DIE_SYSFS define_id_show_func(die_id); static DEVICE_ATTR_RO(die_id); +#endif define_id_show_func(cluster_id); static DEVICE_ATTR_RO(cluster_id); @@ -70,9 +72,11 @@ define_siblings_read_func(cluster_cpus, cluster_cpumask); static BIN_ATTR_RO(cluster_cpus, 0); static BIN_ATTR_RO(cluster_cpus_list, 0); +#ifdef TOPOLOGY_DIE_SYSFS define_siblings_read_func(die_cpus, die_cpumask); static BIN_ATTR_RO(die_cpus, 0); static BIN_ATTR_RO(die_cpus_list, 0); +#endif define_siblings_read_func(package_cpus, core_cpumask); static BIN_ATTR_RO(package_cpus, 0); @@ -103,8 +107,10 @@ static struct bin_attribute *bin_attrs[] = { &bin_attr_core_siblings_list, &bin_attr_cluster_cpus, &bin_attr_cluster_cpus_list, +#ifdef TOPOLOGY_DIE_SYSFS &bin_attr_die_cpus, &bin_attr_die_cpus_list, +#endif &bin_attr_package_cpus, &bin_attr_package_cpus_list, #ifdef CONFIG_SCHED_BOOK @@ -120,7 +126,9 @@ static struct bin_attribute *bin_attrs[] = { static struct attribute *default_attrs[] = { &dev_attr_physical_package_id.attr, +#ifdef TOPOLOGY_DIE_SYSFS &dev_attr_die_id.attr, +#endif &dev_attr_cluster_id.attr, &dev_attr_core_id.attr, #ifdef CONFIG_SCHED_BOOK diff --git a/include/linux/topology.h b/include/linux/topology.h index 0b3704a..8d1bdae 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -180,6 +180,10 @@ static inline int cpu_to_mem(int cpu) #endif /* [!]CONFIG_HAVE_MEMORYLESS_NODES */ +#if defined(topology_die_id) && defined(topology_die_cpumask) +#define TOPOLOGY_DIE_SYSFS +#endif + #ifndef topology_physical_package_id #define topology_physical_package_id(cpu) ((void)(cpu), -1) #endif -- 2.7.4