Merge tag 'locking-urgent-2020-11-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

torvalds · torvalds · commit 855cf1ee4726 · 2020-11-22T13:19:53.000-08:00
Pull locking fix from Thomas Gleixner:
 "A single fix for lockdep which makes the recursion protection cover
  graph lock/unlock"

* tag 'locking-urgent-2020-11-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  lockdep: Put graph lock/unlock under lock_recursion protection
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
@@ -108,19 +108,21 @@ static inline void lockdep_lock(void)
 {
 	DEBUG_LOCKS_WARN_ON(!irqs_disabled());
 
+	__this_cpu_inc(lockdep_recursion);
 	arch_spin_lock(&__lock);
 	__owner = current;
-	__this_cpu_inc(lockdep_recursion);
 }
 
 static inline void lockdep_unlock(void)
 {
+	DEBUG_LOCKS_WARN_ON(!irqs_disabled());
+
 	if (debug_locks && DEBUG_LOCKS_WARN_ON(__owner != current))
 		return;
 
-	__this_cpu_dec(lockdep_recursion);
 	__owner = NULL;
 	arch_spin_unlock(&__lock);
+	__this_cpu_dec(lockdep_recursion);
 }
 
 static inline bool lockdep_assert_locked(void)

Original file line number	Diff line number	Diff line change
`@@ -108,19 +108,21 @@ static inline void lockdep_lock(void)`
`108`	`108`	`{`
`109`	`109`	`DEBUG_LOCKS_WARN_ON(!irqs_disabled());`
`110`	`110`
	`111`	`+ __this_cpu_inc(lockdep_recursion);`
`111`	`112`	`arch_spin_lock(&__lock);`
`112`	`113`	`__owner = current;`
`113`		`- __this_cpu_inc(lockdep_recursion);`
`114`	`114`	`}`
`115`	`115`
`116`	`116`	`static inline void lockdep_unlock(void)`
`117`	`117`	`{`
	`118`	`+ DEBUG_LOCKS_WARN_ON(!irqs_disabled());`
	`119`	`+`
`118`	`120`	`if (debug_locks && DEBUG_LOCKS_WARN_ON(__owner != current))`
`119`	`121`	`return;`
`120`	`122`
`121`		`- __this_cpu_dec(lockdep_recursion);`
`122`	`123`	`__owner = NULL;`
`123`	`124`	`arch_spin_unlock(&__lock);`
	`125`	`+ __this_cpu_dec(lockdep_recursion);`
`124`	`126`	`}`
`125`	`127`
`126`	`128`	`static inline bool lockdep_assert_locked(void)`