Re: + kernel-locking-lockdepc-make-lockdep-initialize-itself-on-demand.patch added to -mm tree

From: Ingo Molnar
Date: Mon Feb 29 2016 - 04:25:31 EST



* Ingo Molnar <mingo@xxxxxxxxxx> wrote:

>
> * Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> > On Tue, 9 Feb 2016 12:12:29 +0100 Ingo Molnar <mingo@xxxxxxxxxx> wrote:
> >
> > > > The conceptual problem is that if some piece of code does spin_lock_init() or
> > > > DEFINE_SPINLOCK(), that lock isn't necessarily initialized yet.
> > >
> > > The conceptual problem is that the data structures are not build time initialized
> > > - but the hlist conversion patch solves that problem nicely!
> > >
> > > So I'm a happy camper.
> >
> > OK, so the below has been in -next for nearly a week, no issues. We
> > should get this into 4.5 to fix the CONFIG_UBSAN_ALIGNMENT issue.
>
> So I think this patch broke liblockdep:
>
> triton:~/tip/tools/lib/lockdep>
>
> In file included from lockdep.c:2:0:
> ../../../kernel/locking/lockdep.c: In function âlook_up_lock_classâ:
> ../../../kernel/locking/lockdep.c:722:2: warning: implicit declaration of function âhlist_for_each_entry_rcuâ [-Wimplicit-function-declaration]
> hlist_for_each_entry_rcu(class, hash_head, hash_entry) {

The patch below fixes it.

Thanks,

Ingo

tools/lib/lockdep/lockdep.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/tools/lib/lockdep/lockdep.c b/tools/lib/lockdep/lockdep.c
index f42b7e9aa48f..a0a2e3a266af 100644
--- a/tools/lib/lockdep/lockdep.c
+++ b/tools/lib/lockdep/lockdep.c
@@ -1,2 +1,8 @@
#include <linux/lockdep.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
+
#include "../../../kernel/locking/lockdep.c"