On Thu, Jul 11, 2019 at 07:43:56PM -0400, Joel Fernandes (Google) wrote: > This patch adds support for checking RCU reader sections in list > traversal macros. Optionally, if the list macro is called under SRCU or > other lock/mutex protection, then appropriate lockdep expressions can be > passed to make the checks pass. > > Existing list_for_each_entry_rcu() invocations don't need to pass the > optional fourth argument (cond) unless they are under some non-RCU > protection and needs to make lockdep check pass. > > Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx> > --- > include/linux/rculist.h | 29 ++++++++++++++++++++++++----- > include/linux/rcupdate.h | 7 +++++++ > kernel/rcu/Kconfig.debug | 11 +++++++++++ > kernel/rcu/update.c | 26 ++++++++++++++++++++++++++ > 4 files changed, 68 insertions(+), 5 deletions(-) > > diff --git a/include/linux/rculist.h b/include/linux/rculist.h > index e91ec9ddcd30..78c15ec6b2c9 100644 > --- a/include/linux/rculist.h > +++ b/include/linux/rculist.h > @@ -40,6 +40,23 @@ static inline void INIT_LIST_HEAD_RCU(struct list_head *list) > */ > #define list_next_rcu(list) (*((struct list_head __rcu **)(&(list)->next))) > > +/* > + * Check during list traversal that we are within an RCU reader > + */ > + > +#define SIXTH_ARG(a1, a2, a3, a4, a5, a6, ...) a6 > +#define COUNT_VARGS(...) SIXTH_ARG(dummy, ## __VA_ARGS__, 4, 3, 2, 1, 0) You don't seem to actually use it in this patch; also linux/kernel.h has COUNT_ARGS().
