This is a note to let you know that I've just added the patch titled
topology/sysfs: export cluster attributes only if an architectures has support
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
topology-sysfs-export-cluster-attributes-only-if-an-.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit e4d3e0f541c6884ea3a9d67839e74293c4cd8512
Author: Heiko Carstens <hca@xxxxxxxxxxxxx>
Date: Mon Nov 29 14:03:08 2021 +0100
topology/sysfs: export cluster attributes only if an architectures has support
[ Upstream commit e795707703b32fecdd7467afcc33ff1e92416c05 ]
The cluster_id and cluster_cpus topology sysfs attributes have been
added with commit c5e22feffdd7 ("topology: Represent clusters of CPUs
within a die").
They are currently only used for x86, arm64, and riscv (via generic
arch topology), however they are still present with bogus default
values for all other 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_cluster_id
and topology_cluster_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
new interface introduced with the v5.16 merge window.
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20211129130309.3256168-3-hca@xxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/Documentation/admin-guide/cputopology.rst b/Documentation/admin-guide/cputopology.rst
index c68d07533c45..ad2238b41439 100644
--- a/Documentation/admin-guide/cputopology.rst
+++ b/Documentation/admin-guide/cputopology.rst
@@ -11,8 +11,8 @@ 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.
+The die and cluster 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 f079a55793ec..9d049724e4b4 100644
--- a/drivers/base/topology.c
+++ b/drivers/base/topology.c
@@ -50,8 +50,10 @@ define_id_show_func(die_id);
static DEVICE_ATTR_RO(die_id);
#endif
+#ifdef TOPOLOGY_CLUSTER_SYSFS
define_id_show_func(cluster_id);
static DEVICE_ATTR_RO(cluster_id);
+#endif
define_id_show_func(core_id);
static DEVICE_ATTR_RO(core_id);
@@ -68,9 +70,11 @@ define_siblings_read_func(core_siblings, core_cpumask);
static BIN_ATTR_RO(core_siblings, 0);
static BIN_ATTR_RO(core_siblings_list, 0);
+#ifdef TOPOLOGY_CLUSTER_SYSFS
define_siblings_read_func(cluster_cpus, cluster_cpumask);
static BIN_ATTR_RO(cluster_cpus, 0);
static BIN_ATTR_RO(cluster_cpus_list, 0);
+#endif
#ifdef TOPOLOGY_DIE_SYSFS
define_siblings_read_func(die_cpus, die_cpumask);
@@ -105,8 +109,10 @@ static struct bin_attribute *bin_attrs[] = {
&bin_attr_thread_siblings_list,
&bin_attr_core_siblings,
&bin_attr_core_siblings_list,
+#ifdef TOPOLOGY_CLUSTER_SYSFS
&bin_attr_cluster_cpus,
&bin_attr_cluster_cpus_list,
+#endif
#ifdef TOPOLOGY_DIE_SYSFS
&bin_attr_die_cpus,
&bin_attr_die_cpus_list,
@@ -129,7 +135,9 @@ static struct attribute *default_attrs[] = {
#ifdef TOPOLOGY_DIE_SYSFS
&dev_attr_die_id.attr,
#endif
+#ifdef TOPOLOGY_CLUSTER_SYSFS
&dev_attr_cluster_id.attr,
+#endif
&dev_attr_core_id.attr,
#ifdef CONFIG_SCHED_BOOK
&dev_attr_book_id.attr,
diff --git a/include/linux/topology.h b/include/linux/topology.h
index 9ec418f58804..6f6f9cdc5274 100644
--- a/include/linux/topology.h
+++ b/include/linux/topology.h
@@ -183,6 +183,9 @@ static inline int cpu_to_mem(int cpu)
#if defined(topology_die_id) && defined(topology_die_cpumask)
#define TOPOLOGY_DIE_SYSFS
#endif
+#if defined(topology_cluster_id) && defined(topology_cluster_cpumask)
+#define TOPOLOGY_CLUSTER_SYSFS
+#endif
#ifndef topology_physical_package_id
#define topology_physical_package_id(cpu) ((void)(cpu), -1)
