Merge tag 'driver-core-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core updatesk from Greg KH:
 "Here is the big set of driver core updates for 6.15-rc1. Lots of stuff
  happened this development cycle, including:

   - kernfs scaling changes to make it even faster thanks to rcu

   - bin_attribute constify work in many subsystems

   - faux bus minor tweaks for the rust bindings

   - rust binding updates for driver core, pci, and platform busses,
     making more functionaliy available to rust drivers. These are all
     due to people actually trying to use the bindings that were in
     6.14.

   - make Rafael and Danilo full co-maintainers of the driver core
     codebase

   - other minor fixes and updates"

* tag 'driver-core-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (52 commits)
  rust: platform: require Send for Driver trait implementers
  rust: pci: require Send for Driver trait implementers
  rust: platform: impl Send + Sync for platform::Device
  rust: pci: impl Send + Sync for pci::Device
  rust: platform: fix unrestricted &mut platform::Device
  rust: pci: fix unrestricted &mut pci::Device
  rust: device: implement device context marker
  rust: pci: use to_result() in enable_device_mem()
  MAINTAINERS: driver core: mark Rafael and Danilo as co-maintainers
  rust/kernel/faux: mark Registration methods inline
  driver core: faux: only create the device if probe() succeeds
  rust/faux: Add missing parent argument to Registration::new()
  rust/faux: Drop #[repr(transparent)] from faux::Registration
  rust: io: fix devres test with new io accessor functions
  rust: io: rename `io::Io` accessors
  kernfs: Move dput() outside of the RCU section.
  efi: rci2: mark bin_attribute as __ro_after_init
  rapidio: constify 'struct bin_attribute'
  firmware: qemu_fw_cfg: constify 'struct bin_attribute'
  powerpc/perf/hv-24x7: Constify 'struct bin_attribute'
  ...

3 files changed, 63 insertions, 29 deletions

diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index c44c5b496355..eaae99602b61 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -403,6 +403,11 @@ static inline struct rdt_hw_resource *resctrl_to_arch_res(struct rdt_resource *r
 
 extern struct mutex rdtgroup_mutex;
 
+static inline const char *rdt_kn_name(const struct kernfs_node *kn)
+{
+	return rcu_dereference_check(kn->name, lockdep_is_held(&rdtgroup_mutex));
+}
+
 extern struct rdt_hw_resource rdt_resources_all[];
 extern struct rdtgroup rdtgroup_default;
 extern struct dentry *debugfs_resctrl;
diff --git a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
index 01fa7890b43f..92ea1472bde9 100644
--- a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
+++ b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
@@ -52,7 +52,8 @@ static char *pseudo_lock_devnode(const struct device *dev, umode_t *mode)
 	rdtgrp = dev_get_drvdata(dev);
 	if (mode)
 		*mode = 0600;
-	return kasprintf(GFP_KERNEL, "pseudo_lock/%s", rdtgrp->kn->name);
+	guard(mutex)(&rdtgroup_mutex);
+	return kasprintf(GFP_KERNEL, "pseudo_lock/%s", rdt_kn_name(rdtgrp->kn));
 }
 
 static const struct class pseudo_lock_class = {
@@ -1298,6 +1299,7 @@ int rdtgroup_pseudo_lock_create(struct rdtgroup *rdtgrp)
 	struct task_struct *thread;
 	unsigned int new_minor;
 	struct device *dev;
+	char *kn_name __free(kfree) = NULL;
 	int ret;
 
 	ret = pseudo_lock_region_alloc(plr);
@@ -1309,6 +1311,11 @@ int rdtgroup_pseudo_lock_create(struct rdtgroup *rdtgrp)
 		ret = -EINVAL;
 		goto out_region;
 	}
+	kn_name = kstrdup(rdt_kn_name(rdtgrp->kn), GFP_KERNEL);
+	if (!kn_name) {
+		ret = -ENOMEM;
+		goto out_cstates;
+	}
 
 	plr->thread_done = 0;
 
@@ -1353,8 +1360,7 @@ int rdtgroup_pseudo_lock_create(struct rdtgroup *rdtgrp)
 	mutex_unlock(&rdtgroup_mutex);
 
 	if (!IS_ERR_OR_NULL(debugfs_resctrl)) {
-		plr->debugfs_dir = debugfs_create_dir(rdtgrp->kn->name,
-						      debugfs_resctrl);
+		plr->debugfs_dir = debugfs_create_dir(kn_name, debugfs_resctrl);
 		if (!IS_ERR_OR_NULL(plr->debugfs_dir))
 			debugfs_create_file("pseudo_lock_measure", 0200,
 					    plr->debugfs_dir, rdtgrp,
@@ -1363,7 +1369,7 @@ int rdtgroup_pseudo_lock_create(struct rdtgroup *rdtgrp)
 
 	dev = device_create(&pseudo_lock_class, NULL,
 			    MKDEV(pseudo_lock_major, new_minor),
-			    rdtgrp, "%s", rdtgrp->kn->name);
+			    rdtgrp, "%s", kn_name);
 
 	mutex_lock(&rdtgroup_mutex);
 
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index c6274d40b217..93ec829015f1 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -944,14 +944,14 @@ int proc_resctrl_show(struct seq_file *s, struct pid_namespace *ns,
 			continue;
 
 		seq_printf(s, "res:%s%s\n", (rdtg == &rdtgroup_default) ? "/" : "",
-			   rdtg->kn->name);
+			   rdt_kn_name(rdtg->kn));
 		seq_puts(s, "mon:");
 		list_for_each_entry(crg, &rdtg->mon.crdtgrp_list,
 				    mon.crdtgrp_list) {
 			if (!resctrl_arch_match_rmid(tsk, crg->mon.parent->closid,
 						     crg->mon.rmid))
 				continue;
-			seq_printf(s, "%s", crg->kn->name);
+			seq_printf(s, "%s", rdt_kn_name(crg->kn));
 			break;
 		}
 		seq_putc(s, '\n');
@@ -984,10 +984,20 @@ static int rdt_last_cmd_status_show(struct kernfs_open_file *of,
 	return 0;
 }
 
+static void *rdt_kn_parent_priv(struct kernfs_node *kn)
+{
+	/*
+	 * The parent pointer is only valid within RCU section since it can be
+	 * replaced.
+	 */
+	guard(rcu)();
+	return rcu_dereference(kn->__parent)->priv;
+}
+
 static int rdt_num_closids_show(struct kernfs_open_file *of,
 				struct seq_file *seq, void *v)
 {
-	struct resctrl_schema *s = of->kn->parent->priv;
+	struct resctrl_schema *s = rdt_kn_parent_priv(of->kn);
 
 	seq_printf(seq, "%u\n", s->num_closid);
 	return 0;
@@ -996,7 +1006,7 @@ static int rdt_num_closids_show(struct kernfs_open_file *of,
 static int rdt_default_ctrl_show(struct kernfs_open_file *of,
 			     struct seq_file *seq, void *v)
 {
-	struct resctrl_schema *s = of->kn->parent->priv;
+	struct resctrl_schema *s = rdt_kn_parent_priv(of->kn);
 	struct rdt_resource *r = s->res;
 
 	seq_printf(seq, "%x\n", resctrl_get_default_ctrl(r));
@@ -1006,7 +1016,7 @@ static int rdt_default_ctrl_show(struct kernfs_open_file *of,
 static int rdt_min_cbm_bits_show(struct kernfs_open_file *of,
 			     struct seq_file *seq, void *v)
 {
-	struct resctrl_schema *s = of->kn->parent->priv;
+	struct resctrl_schema *s = rdt_kn_parent_priv(of->kn);
 	struct rdt_resource *r = s->res;
 
 	seq_printf(seq, "%u\n", r->cache.min_cbm_bits);
@@ -1016,7 +1026,7 @@ static int rdt_min_cbm_bits_show(struct kernfs_open_file *of,
 static int rdt_shareable_bits_show(struct kernfs_open_file *of,
 				   struct seq_file *seq, void *v)
 {
-	struct resctrl_schema *s = of->kn->parent->priv;
+	struct resctrl_schema *s = rdt_kn_parent_priv(of->kn);
 	struct rdt_resource *r = s->res;
 
 	seq_printf(seq, "%x\n", r->cache.shareable_bits);
@@ -1040,7 +1050,7 @@ static int rdt_shareable_bits_show(struct kernfs_open_file *of,
 static int rdt_bit_usage_show(struct kernfs_open_file *of,
 			      struct seq_file *seq, void *v)
 {
-	struct resctrl_schema *s = of->kn->parent->priv;
+	struct resctrl_schema *s = rdt_kn_parent_priv(of->kn);
 	/*
 	 * Use unsigned long even though only 32 bits are used to ensure
 	 * test_bit() is used safely.
@@ -1122,7 +1132,7 @@ static int rdt_bit_usage_show(struct kernfs_open_file *of,
 static int rdt_min_bw_show(struct kernfs_open_file *of,
 			     struct seq_file *seq, void *v)
 {
-	struct resctrl_schema *s = of->kn->parent->priv;
+	struct resctrl_schema *s = rdt_kn_parent_priv(of->kn);
 	struct rdt_resource *r = s->res;
 
 	seq_printf(seq, "%u\n", r->membw.min_bw);
@@ -1132,7 +1142,7 @@ static int rdt_min_bw_show(struct kernfs_open_file *of,
 static int rdt_num_rmids_show(struct kernfs_open_file *of,
 			      struct seq_file *seq, void *v)
 {
-	struct rdt_resource *r = of->kn->parent->priv;
+	struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
 
 	seq_printf(seq, "%d\n", r->num_rmid);
 
@@ -1142,7 +1152,7 @@ static int rdt_num_rmids_show(struct kernfs_open_file *of,
 static int rdt_mon_features_show(struct kernfs_open_file *of,
 				 struct seq_file *seq, void *v)
 {
-	struct rdt_resource *r = of->kn->parent->priv;
+	struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
 	struct mon_evt *mevt;
 
 	list_for_each_entry(mevt, &r->evt_list, list) {
@@ -1157,7 +1167,7 @@ static int rdt_mon_features_show(struct kernfs_open_file *of,
 static int rdt_bw_gran_show(struct kernfs_open_file *of,
 			     struct seq_file *seq, void *v)
 {
-	struct resctrl_schema *s = of->kn->parent->priv;
+	struct resctrl_schema *s = rdt_kn_parent_priv(of->kn);
 	struct rdt_resource *r = s->res;
 
 	seq_printf(seq, "%u\n", r->membw.bw_gran);
@@ -1167,7 +1177,7 @@ static int rdt_bw_gran_show(struct kernfs_open_file *of,
 static int rdt_delay_linear_show(struct kernfs_open_file *of,
 			     struct seq_file *seq, void *v)
 {
-	struct resctrl_schema *s = of->kn->parent->priv;
+	struct resctrl_schema *s = rdt_kn_parent_priv(of->kn);
 	struct rdt_resource *r = s->res;
 
 	seq_printf(seq, "%u\n", r->membw.delay_linear);
@@ -1185,7 +1195,7 @@ static int max_threshold_occ_show(struct kernfs_open_file *of,
 static int rdt_thread_throttle_mode_show(struct kernfs_open_file *of,
 					 struct seq_file *seq, void *v)
 {
-	struct resctrl_schema *s = of->kn->parent->priv;
+	struct resctrl_schema *s = rdt_kn_parent_priv(of->kn);
 	struct rdt_resource *r = s->res;
 
 	switch (r->membw.throttle_mode) {
@@ -1259,7 +1269,7 @@ static enum resctrl_conf_type resctrl_peer_type(enum resctrl_conf_type my_type)
 static int rdt_has_sparse_bitmasks_show(struct kernfs_open_file *of,
 					struct seq_file *seq, void *v)
 {
-	struct resctrl_schema *s = of->kn->parent->priv;
+	struct resctrl_schema *s = rdt_kn_parent_priv(of->kn);
 	struct rdt_resource *r = s->res;
 
 	seq_printf(seq, "%u\n", r->cache.arch_has_sparse_bitmasks);
@@ -1670,7 +1680,7 @@ static int mbm_config_show(struct seq_file *s, struct rdt_resource *r, u32 evtid
 static int mbm_total_bytes_config_show(struct kernfs_open_file *of,
 				       struct seq_file *seq, void *v)
 {
-	struct rdt_resource *r = of->kn->parent->priv;
+	struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
 
 	mbm_config_show(seq, r, QOS_L3_MBM_TOTAL_EVENT_ID);
 
@@ -1680,7 +1690,7 @@ static int mbm_total_bytes_config_show(struct kernfs_open_file *of,
 static int mbm_local_bytes_config_show(struct kernfs_open_file *of,
 				       struct seq_file *seq, void *v)
 {
-	struct rdt_resource *r = of->kn->parent->priv;
+	struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
 
 	mbm_config_show(seq, r, QOS_L3_MBM_LOCAL_EVENT_ID);
 
@@ -1787,7 +1797,7 @@ static ssize_t mbm_total_bytes_config_write(struct kernfs_open_file *of,
 					    char *buf, size_t nbytes,
 					    loff_t off)
 {
-	struct rdt_resource *r = of->kn->parent->priv;
+	struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
 	int ret;
 
 	/* Valid input requires a trailing newline */
@@ -1813,7 +1823,7 @@ static ssize_t mbm_local_bytes_config_write(struct kernfs_open_file *of,
 					    char *buf, size_t nbytes,
 					    loff_t off)
 {
-	struct rdt_resource *r = of->kn->parent->priv;
+	struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
 	int ret;
 
 	/* Valid input requires a trailing newline */
@@ -2513,12 +2523,13 @@ static struct rdtgroup *kernfs_to_rdtgroup(struct kernfs_node *kn)
 		 * resource. "info" and its subdirectories don't
 		 * have rdtgroup structures, so return NULL here.
 		 */
-		if (kn == kn_info || kn->parent == kn_info)
+		if (kn == kn_info ||
+		    rcu_access_pointer(kn->__parent) == kn_info)
 			return NULL;
 		else
 			return kn->priv;
 	} else {
-		return kn->parent->priv;
+		return rdt_kn_parent_priv(kn);
 	}
 }
 
@@ -3752,7 +3763,7 @@ out_unlock:
  */
 static bool is_mon_groups(struct kernfs_node *kn, const char *name)
 {
-	return (!strcmp(kn->name, "mon_groups") &&
+	return (!strcmp(rdt_kn_name(kn), "mon_groups") &&
 		strcmp(name, "mon_groups"));
 }
 
@@ -3867,9 +3878,18 @@ static int rdtgroup_rmdir_ctrl(struct rdtgroup *rdtgrp, cpumask_var_t tmpmask)
 	return 0;
 }
 
+static struct kernfs_node *rdt_kn_parent(struct kernfs_node *kn)
+{
+	/*
+	 * Valid within the RCU section it was obtained or while rdtgroup_mutex
+	 * is held.
+	 */
+	return rcu_dereference_check(kn->__parent, lockdep_is_held(&rdtgroup_mutex));
+}
+
 static int rdtgroup_rmdir(struct kernfs_node *kn)
 {
-	struct kernfs_node *parent_kn = kn->parent;
+	struct kernfs_node *parent_kn;
 	struct rdtgroup *rdtgrp;
 	cpumask_var_t tmpmask;
 	int ret = 0;
@@ -3882,6 +3902,7 @@ static int rdtgroup_rmdir(struct kernfs_node *kn)
 		ret = -EPERM;
 		goto out;
 	}
+	parent_kn = rdt_kn_parent(kn);
 
 	/*
 	 * If the rdtgroup is a ctrl_mon group and parent directory
@@ -3899,7 +3920,7 @@ static int rdtgroup_rmdir(struct kernfs_node *kn)
 			ret = rdtgroup_rmdir_ctrl(rdtgrp, tmpmask);
 		}
 	} else if (rdtgrp->type == RDTMON_GROUP &&
-		 is_mon_groups(parent_kn, kn->name)) {
+		 is_mon_groups(parent_kn, rdt_kn_name(kn))) {
 		ret = rdtgroup_rmdir_mon(rdtgrp, tmpmask);
 	} else {
 		ret = -EPERM;
@@ -3950,6 +3971,7 @@ static void mongrp_reparent(struct rdtgroup *rdtgrp,
 static int rdtgroup_rename(struct kernfs_node *kn,
 			   struct kernfs_node *new_parent, const char *new_name)
 {
+	struct kernfs_node *kn_parent;
 	struct rdtgroup *new_prdtgrp;
 	struct rdtgroup *rdtgrp;
 	cpumask_var_t tmpmask;
@@ -3984,8 +4006,9 @@ static int rdtgroup_rename(struct kernfs_node *kn,
 		goto out;
 	}
 
-	if (rdtgrp->type != RDTMON_GROUP || !kn->parent ||
-	    !is_mon_groups(kn->parent, kn->name)) {
+	kn_parent = rdt_kn_parent(kn);
+	if (rdtgrp->type != RDTMON_GROUP || !kn_parent ||
+	    !is_mon_groups(kn_parent, rdt_kn_name(kn))) {
 		rdt_last_cmd_puts("Source must be a MON group\n");
 		ret = -EPERM;
 		goto out;