Signed-off-by: Eric Biederman <redacted>
---
 include/linux/sysctl.h |    4 ++
 kernel/sysctl.c        |  108 ++++++++++++++++++++++++++++++++++++++---------
 2 files changed, 91 insertions(+), 21 deletions(-)

diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 39d471d..ec9b1dd 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h

@@ -28,6 +28,7 @@
 #include <linux/kernel.h>
 #include <linux/types.h>
 #include <linux/compiler.h>
+#include <linux/lockdep.h>
 
 struct file;
 struct completion;

@@ -1087,6 +1088,9 @@ struct ctl_table_header
 	struct ctl_table *attached_by;
 	struct ctl_table *attached_to;
 	struct ctl_table_header *parent;
+#ifdef CONFIG_PROVE_LOCKING
+	struct lockdep_map dep_map;
+#endif
 };
 
 /* struct ctl_path describes where in the hierarchy a table is added */

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index c5ef44f..ea8cc39 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c

@@ -1454,12 +1454,63 @@ static struct ctl_table dev_table[] = {
 
 static DEFINE_SPINLOCK(sysctl_lock);
 
+#ifndef CONFIG_PROVE_LOCKING
+
+# define lock_sysctl() spin_lock(&sysctl_lock)
+# define unlock_sysctl() spin_unlock(&sysctl_lock)
+
+static inline void table_acquire_use(struct ctl_table_header *hdr) { }
+static inline void table_release_use(struct ctl_table_header *hdr) { }
+static inline void table_acquire(struct ctl_table_header *hdr) { }
+static inline void table_contended(struct ctl_table_header *hdr) { }
+static inline void table_acquired(struct ctl_table_header *hdr) { }
+static inline void table_release(struct ctl_table_header *hdr) { }
+
+#else	/* CONFIG_PROVE_LOCKING */
+
+#  define lock_sysctl() __raw_spin_lock(&sysctl_lock.raw_lock)
+#  define unlock_sysctl() __raw_spin_unlock(&sysctl_lock.raw_lock)

+static inline void table_acquire_use(struct ctl_table_header *hdr)
+{
+	lock_acquire(&hdr->dep_map, 0, 0, 1, 2, NULL, _RET_IP_);
+	lock_acquired(&hdr->dep_map, _RET_IP_);
+}
+
+static inline void table_release_use(struct ctl_table_header *hdr)
+{
+	lock_release(&hdr->dep_map, 0, _RET_IP_);
+}
+
+static inline void table_acquire(struct ctl_table_header *hdr)
+{
+	lock_acquire(&hdr->dep_map, 0, 0, 0, 2, NULL, _RET_IP_);
+}
+
+static inline void table_contended(struct ctl_table_header *hdr)
+{
+	lock_contended(&hdr->dep_map, _RET_IP_);
+}
+
+static inline void table_acquired(struct ctl_table_header *hdr)
+{
+	lock_acquired(&hdr->dep_map, _RET_IP_);
+}
+
+static inline void table_release(struct ctl_table_header *hdr)
+{
+	lock_release(&hdr->dep_map, 0, _RET_IP_);
+}
+
+#endif /* CONFIG_PROVE_LOCKING */
+
 /* called under sysctl_lock */
 static int use_table(struct ctl_table_header *p)
 {
 	if (unlikely(p->unregistering))
 		return 0;
 	p->used++;
+	table_acquire_use(p);
 	return 1;
 }
 

@@ -1469,6 +1520,8 @@ static void unuse_table(struct ctl_table_header *p)
 	if (!--p->used)
 		if (unlikely(p->unregistering))
 			complete(p->unregistering);
+
+	table_release_use(p);
 }
 
 /* called under sysctl_lock, will reacquire if has to wait */

@@ -1478,47 +1531,54 @@ static void start_unregistering(struct ctl_table_header *p)
 	 * if p->used is 0, nobody will ever touch that entry again;
 	 * we'll eliminate all paths to it before dropping sysctl_lock
 	 */
+	table_acquire(p);
 	if (unlikely(p->used)) {
 		struct completion wait;
+		table_contended(p);
+
 		init_completion(&wait);
 		p->unregistering = &wait;
-		spin_unlock(&sysctl_lock);
+		unlock_sysctl();
 		wait_for_completion(&wait);
-		spin_lock(&sysctl_lock);
+		lock_sysctl();
 	} else {
 		/* anything non-NULL; we'll never dereference it */
 		p->unregistering = ERR_PTR(-EINVAL);
 	}
+	table_acquired(p);
+
 	/*
 	 * do not remove from the list until nobody holds it; walking the
 	 * list in do_sysctl() relies on that.
 	 */
 	list_del_init(&p->ctl_entry);
+
+	table_release(p);
 }
 

@@ -1951,7 +2011,13 @@ struct ctl_table_header *__register_sysctl_paths(
 		return NULL;
 	}
 #endif
-	spin_lock(&sysctl_lock);
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	{
+		static struct lock_class_key __key;
+		lockdep_init_map(&header->dep_map, "sysctl_used", &__key, 0);
+	}
+#endif