From: Bart Van Assche <bvanassche@acm.org>
Date: Thu, 14 Feb 2019 23:00:52 +0000 (-0800)
Subject: locking/lockdep: Verify whether lock objects are small enough to be used as class keys
X-Git-Tag: v5.1-rc1~164^2~6
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=4bf508621855613ca2ac782f70c3171e0e8bb011;p=linux.git

locking/lockdep: Verify whether lock objects are small enough to be used as class keys

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20190214230058.196511-18-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 630be9ac6253..84427441824e 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -758,6 +758,17 @@ static bool assign_lock_key(struct lockdep_map *lock)
 {
 	unsigned long can_addr, addr = (unsigned long)lock;
 
+#ifdef __KERNEL__
+	/*
+	 * lockdep_free_key_range() assumes that struct lock_class_key
+	 * objects do not overlap. Since we use the address of lock
+	 * objects as class key for static objects, check whether the
+	 * size of lock_class_key objects does not exceed the size of
+	 * the smallest lock object.
+	 */
+	BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(raw_spinlock_t));
+#endif
+
 	if (__is_kernel_percpu_address(addr, &can_addr))
 		lock->key = (void *)can_addr;
 	else if (__is_module_percpu_address(addr, &can_addr))