[tip:locking/core] tools/lib/lockdep: Fix undefined symbol prandom_u32

[tip-bot for Ben Hutchings]

Commit-ID:  3752466b6bf04868296ac6bc27ea1765008636d8
Gitweb:     http://git.kernel.org/tip/3752466b6bf04868296ac6bc27ea1765008636d8
Author:     Ben Hutchings <ben@xxxxxxxxxxxxxxx>
AuthorDate: Thu, 25 May 2017 12:58:31 +0000
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Mon, 5 Jun 2017 09:28:02 +0200

tools/lib/lockdep: Fix undefined symbol prandom_u32

__lock_pin_lock() now calls prandom_u32() which is not defined in
liblockdep.  __lock_pin_lock() and its caller lock_pin_lock() are dead
code in liblockdep, but we still need to provide a definition of
prandom_u32() in case lazy binding is disabled.

Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: a.p.zijlstra@xxxxxxxxx
Fixes: e7904a28f533 ("locking/lockdep, sched/core: Implement a better ...")
Link: http://lkml.kernel.org/r/20170525130005.5947-2-alexander.levin@xxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 tools/lib/lockdep/lockdep.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tools/lib/lockdep/lockdep.c b/tools/lib/lockdep/lockdep.c
index a0a2e3a..443acb1 100644
--- a/tools/lib/lockdep/lockdep.c
+++ b/tools/lib/lockdep/lockdep.c
@@ -1,8 +1,15 @@
 #include <linux/lockdep.h>
+#include <stdlib.h>
 
 /* Trivial API wrappers, we don't (yet) have RCU in user-space: */
 #define hlist_for_each_entry_rcu	hlist_for_each_entry
 #define hlist_add_head_rcu		hlist_add_head
 #define hlist_del_rcu			hlist_del
 
+u32 prandom_u32(void)
+{
+	/* Used only by lock_pin_lock() which is dead code */
+	abort();
+}
+
 #include "../../../kernel/locking/lockdep.c"