From a9e3760b0838299649c0d57cca44daaf40ba3c33 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 14 Sep 2026 22:12:34 -1000 Subject: sched_ext: Maintain an online cid mask in the scheduler arena Schedulers on the default cid mapping treat [0, nr_online_cids) as the online set and restart on hotplug. Schedulers that install their own mapping with scx_bpf_cid_override() have no way to learn which cids are online: the count no longer identifies members and the CPU-form cpumask is unusable from cid programs. This is an obvious hole in the cid API. Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's arena, allocated alongside the per-CPU scratch masks and populated after the cid mapping is finalized and before ops.init(), for child schedulers too. The pointer stays valid through ops.exit() with no reference to take. It is the arena offset as a void pointer, the same form struct_ops arena arguments arrive in. The verifier types the void return as a scalar for the program's arena cast. The mask follows the SCX hotplug notifications: seeded from cpu_active_mask and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask only inside a hotplug transition. Updates walk the scheduler list under the lock that also serializes unlinking. Reads are live, not atomic snapshots. Root initialization excludes hotplug. v2: Reworded the getter kerneldoc (Andrea Righi). Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi --- drivers/of/kobj.c | 165 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 165 insertions(+) create mode 100644 drivers/of/kobj.c (limited to 'drivers/of/kobj.c') diff --git a/drivers/of/kobj.c b/drivers/of/kobj.c new file mode 100644 index 000000000..1bb61a2c3 --- /dev/null +++ b/drivers/of/kobj.c @@ -0,0 +1,165 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include + +#include "of_private.h" + +/* true when node is initialized */ +static int of_node_is_initialized(const struct device_node *node) +{ + return node && node->kobj.state_initialized; +} + +/* true when node is attached (i.e. present on sysfs) */ +int of_node_is_attached(const struct device_node *node) +{ + return node && node->kobj.state_in_sysfs; +} + + +#ifndef CONFIG_OF_DYNAMIC +static void of_node_release(struct kobject *kobj) +{ + /* Without CONFIG_OF_DYNAMIC, no nodes gets freed */ +} +#endif /* CONFIG_OF_DYNAMIC */ + +const struct kobj_type of_node_ktype = { + .release = of_node_release, +}; + +static ssize_t of_node_property_read(struct file *filp, struct kobject *kobj, + const struct bin_attribute *bin_attr, char *buf, + loff_t offset, size_t count) +{ + struct property *pp = container_of(bin_attr, struct property, attr); + return memory_read_from_buffer(buf, count, &offset, pp->value, pp->length); +} + +/* always return newly allocated name, caller must free after use */ +static const char *safe_name(const struct kobject *kobj, const char *orig_name) +{ + const char *name = orig_name; + struct kernfs_node *kn; + int i = 0; + + /* don't be a hero. After 16 tries give up */ + while (i < 16 && (kn = sysfs_get_dirent(kobj->sd, name))) { + sysfs_put(kn); + if (name != orig_name) + kfree(name); + name = kasprintf(GFP_KERNEL, "%s#%i", orig_name, ++i); + } + + if (name == orig_name) { + name = kstrdup(orig_name, GFP_KERNEL); + } else { + pr_warn("Duplicate name in %s, renamed to \"%s\"\n", + kobject_name(kobj), name); + } + return name; +} + +int __of_add_property_sysfs(struct device_node *np, struct property *pp) +{ + int rc; + + /* Important: Don't leak passwords */ + bool secure = strncmp(pp->name, "security-", 9) == 0; + + if (!IS_ENABLED(CONFIG_SYSFS)) + return 0; + + if (!of_kset || !of_node_is_attached(np)) + return 0; + + sysfs_bin_attr_init(&pp->attr); + pp->attr.attr.name = safe_name(&np->kobj, pp->name); + pp->attr.attr.mode = secure ? 0400 : 0444; + pp->attr.size = secure ? 0 : pp->length; + pp->attr.read = of_node_property_read; + + rc = sysfs_create_bin_file(&np->kobj, &pp->attr); + WARN(rc, "error adding attribute %s to node %pOF\n", pp->name, np); + return rc; +} + +void __of_sysfs_remove_bin_file(struct device_node *np, const struct property *prop) +{ + if (!IS_ENABLED(CONFIG_SYSFS)) + return; + + sysfs_remove_bin_file(&np->kobj, &prop->attr); + kfree(prop->attr.attr.name); +} + +void __of_remove_property_sysfs(struct device_node *np, const struct property *prop) +{ + /* at early boot, bail here and defer setup to of_init() */ + if (of_kset && of_node_is_attached(np)) + __of_sysfs_remove_bin_file(np, prop); +} + +void __of_update_property_sysfs(struct device_node *np, struct property *newprop, + const struct property *oldprop) +{ + /* At early boot, bail out and defer setup to of_init() */ + if (!of_kset) + return; + + if (oldprop) + __of_sysfs_remove_bin_file(np, oldprop); + __of_add_property_sysfs(np, newprop); +} + +int __of_attach_node_sysfs(struct device_node *np) +{ + const char *name; + struct kobject *parent; + struct property *pp; + int rc; + + if (!IS_ENABLED(CONFIG_SYSFS) || !of_kset) + return 0; + + np->kobj.kset = of_kset; + if (!np->parent) { + /* Nodes without parents are new top level trees */ + name = safe_name(&of_kset->kobj, "base"); + parent = NULL; + } else { + name = safe_name(&np->parent->kobj, kbasename(np->full_name)); + parent = &np->parent->kobj; + } + if (!name) + return -ENOMEM; + + rc = kobject_add(&np->kobj, parent, "%s", name); + kfree(name); + if (rc) + return rc; + + for_each_property_of_node(np, pp) + __of_add_property_sysfs(np, pp); + + of_node_get(np); + return 0; +} + +void __of_detach_node_sysfs(struct device_node *np) +{ + struct property *pp; + + BUG_ON(!of_node_is_initialized(np)); + if (!of_kset) + return; + + /* only remove properties if on sysfs */ + if (of_node_is_attached(np)) { + for_each_property_of_node(np, pp) + __of_sysfs_remove_bin_file(np, pp); + kobject_del(&np->kobj); + } + + of_node_put(np); +} -- cgit v1.3.1