Driver core fixes for 6.0-rc5

Here are some small driver core and debugfs fixes for 6.0-rc5.
 
 Included in here are:
   - multiple attempts to get the arch_topology code to work properly on
     non-cluster SMT systems.  First attempt caused build breakages in
     linux-next and 0-day, second try worked.
   - debugfs fixes for a long-suffering memory leak.  The pattern of
     debugfs_remove(debugfs_lookup(...)) turns out to leak dentries, so
     add debugfs_lookup_and_remove() to fix this problem.  Also fix up
     the scheduler debug code that highlighted this problem.  Fixes for
     other subsystems will be trickling in over the next few months for
     this same issue once the debugfs function is merged.
 
 All of these have been in linux-next since Wednesday with no reported
 problems.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-6.0-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core fixes from Greg KH:
 "Here are some small driver core and debugfs fixes for 6.0-rc5.

  Included in here are:

   - multiple attempts to get the arch_topology code to work properly on
     non-cluster SMT systems. First attempt caused build breakages in
     linux-next and 0-day, second try worked.

   - debugfs fixes for a long-suffering memory leak. The pattern of
     debugfs_remove(debugfs_lookup(...)) turns out to leak dentries, so
     add debugfs_lookup_and_remove() to fix this problem. Also fix up
     the scheduler debug code that highlighted this problem. Fixes for
     other subsystems will be trickling in over the next few months for
     this same issue once the debugfs function is merged.

  All of these have been in linux-next since Wednesday with no reported
  problems"

* tag 'driver-core-6.0-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
  arch_topology: Make cluster topology span at least SMT CPUs
  sched/debug: fix dentry leak in update_sched_domain_debugfs
  debugfs: add debugfs_lookup_and_remove()
  driver core: fix driver_set_override() issue with empty strings
  Revert "arch_topology: Make cluster topology span at least SMT CPUs"
  arch_topology: Make cluster topology span at least SMT CPUs

drivers/base/arch_topology.c

@@ -724,7 +724,7 @@ const struct cpumask *cpu_clustergroup_mask(int cpu)
 	 */
 	if (cpumask_subset(cpu_coregroup_mask(cpu),
 			   &cpu_topology[cpu].cluster_sibling))
-		return get_cpu_mask(cpu);
+		return topology_sibling_cpumask(cpu);
 
 	return &cpu_topology[cpu].cluster_sibling;
 }

drivers/base/driver.c

@@ -63,6 +63,12 @@ int driver_set_override(struct device *dev, const char **override,
 	if (len >= (PAGE_SIZE - 1))
 		return -EINVAL;
 
+	/*
+	 * Compute the real length of the string in case userspace sends us a
+	 * bunch of \0 characters like python likes to do.
+	 */
+	len = strlen(s);
+
 	if (!len) {
 		/* Empty string passed - clear override */
 		device_lock(dev);

fs/debugfs/inode.c

@@ -744,6 +744,28 @@ void debugfs_remove(struct dentry *dentry)
 }
 EXPORT_SYMBOL_GPL(debugfs_remove);
 
+/**
+ * debugfs_lookup_and_remove - lookup a directory or file and recursively remove it
+ * @name: a pointer to a string containing the name of the item to look up.
+ * @parent: a pointer to the parent dentry of the item.
+ *
+ * This is the equlivant of doing something like
+ * debugfs_remove(debugfs_lookup(..)) but with the proper reference counting
+ * handled for the directory being looked up.
+ */
+void debugfs_lookup_and_remove(const char *name, struct dentry *parent)
+{
+	struct dentry *dentry;
+
+	dentry = debugfs_lookup(name, parent);
+	if (!dentry)
+		return;
+
+	debugfs_remove(dentry);
+	dput(dentry);
+}
+EXPORT_SYMBOL_GPL(debugfs_lookup_and_remove);
+
 /**
  * debugfs_rename - rename a file/directory in the debugfs filesystem
  * @old_dir: a pointer to the parent dentry for the renamed object. This

include/linux/debugfs.h

@@ -91,6 +91,8 @@ struct dentry *debugfs_create_automount(const char *name,
 void debugfs_remove(struct dentry *dentry);
 #define debugfs_remove_recursive debugfs_remove
 
+void debugfs_lookup_and_remove(const char *name, struct dentry *parent);
+
 const struct file_operations *debugfs_real_fops(const struct file *filp);
 
 int debugfs_file_get(struct dentry *dentry);
@@ -225,6 +227,10 @@ static inline void debugfs_remove(struct dentry *dentry)
 static inline void debugfs_remove_recursive(struct dentry *dentry)
 { }
 
+static inline void debugfs_lookup_and_remove(const char *name,
+					     struct dentry *parent)
+{ }
+
 const struct file_operations *debugfs_real_fops(const struct file *filp);
 
 static inline int debugfs_file_get(struct dentry *dentry)

kernel/sched/debug.c

@@ -416,7 +416,7 @@ void update_sched_domain_debugfs(void)
 		char buf[32];
 
 		snprintf(buf, sizeof(buf), "cpu%d", cpu);
-		debugfs_remove(debugfs_lookup(buf, sd_dentry));
+		debugfs_lookup_and_remove(buf, sd_dentry);
 		d_cpu = debugfs_create_dir(buf, sd_dentry);
 
 		i = 0;