Re: [RFC 1/6] rcu: Add support for consolidated-RCU reader checking
From: Joel Fernandes <hidden>
Date: 2019-06-03 19:42:16
Also in:
linux-acpi, linux-pci, linux-pm, lkml, rcu
Subsystem:
read-copy update (rcu), the rest · Maintainers:
"Paul E. McKenney", Frederic Weisbecker, Neeraj Upadhyay, Joel Fernandes, Josh Triplett, Boqun Feng, Uladzislau Rezki, Linus Torvalds
On Mon, Jun 03, 2019 at 10:18:47AM -0400, Joel Fernandes wrote:
On Mon, Jun 03, 2019 at 10:01:28AM +0200, Peter Zijlstra wrote:quoted
On Sat, Jun 01, 2019 at 06:27:33PM -0400, Joel Fernandes (Google) wrote:quoted
+#define list_for_each_entry_rcu(pos, head, member, cond...) \ + if (COUNT_VARGS(cond) != 0) { \ + __list_check_rcu_cond(0, ## cond); \ + } else { \ + __list_check_rcu(); \ + } \ + for (pos = list_entry_rcu((head)->next, typeof(*pos), member); \ + &pos->member != (head); \ pos = list_entry_rcu(pos->member.next, typeof(*pos), member)) /**@@ -621,7 +648,12 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n, * the _rcu list-mutation primitives such as hlist_add_head_rcu() * as long as the traversal is guarded by rcu_read_lock(). */ +#define hlist_for_each_entry_rcu(pos, head, member, cond...) \ + if (COUNT_VARGS(cond) != 0) { \ + __list_check_rcu_cond(0, ## cond); \ + } else { \ + __list_check_rcu(); \ + } \ for (pos = hlist_entry_safe (rcu_dereference_raw(hlist_first_rcu(head)),\ typeof(*(pos)), member); \ pos; \This breaks code like: if (...) list_for_each_entry_rcu(...); as they are no longer a single statement. You'll have to frob it into the initializer part of the for statement.Thanks a lot for that. I fixed it as below (diff is on top of the patch): If not for that '##' , I could have abstracted the whole if/else expression into its own macro and called it from list_for_each_entry_rcu() to keep it more clean.
Actually was able to roll the if/else into its own macro as well, thus keeping it clean. thanks! ---8<-----------------------
diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index b641fdd9f1a2..cc9c382b080c 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h@@ -43,7 +43,11 @@ static inline void INIT_LIST_HEAD_RCU(struct list_head *list) /* * Check during list traversal that we are within an RCU reader */ -#define __list_check_rcu() \ + +#define SIXTH_ARG(a1, a2, a3, a4, a5, a6, ...) a6 +#define COUNT_VARGS(...) SIXTH_ARG(dummy, ## __VA_ARGS__, 4, 3, 2, 1, 0) + +#define __list_check_rcu_nocond() \ RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(), \ "RCU-list traversed in non-reader section!")
@@ -59,6 +63,16 @@ static inline void __list_check_rcu_cond(int dummy, ...) RCU_LOCKDEP_WARN(!cond && !rcu_read_lock_any_held(), "RCU-list traversed in non-reader section!"); } + +#define __list_check_rcu(cond...) \ + ({ \ + if (COUNT_VARGS(cond) != 0) { \ + __list_check_rcu_cond(0, ## cond); \ + } else { \ + __list_check_rcu_nocond(); \ + } \ + }) + /* * Insert a new entry between two known consecutive entries. *
@@ -357,9 +371,6 @@ static inline void list_splice_tail_init_rcu(struct list_head *list, member) : NULL; \ }) -#define SIXTH_ARG(a1, a2, a3, a4, a5, a6, ...) a6 -#define COUNT_VARGS(...) SIXTH_ARG(dummy, ## __VA_ARGS__, 4, 3, 2, 1, 0) - /** * list_for_each_entry_rcu - iterate over rcu list of given type * @pos: the type * to use as a loop cursor.
@@ -371,12 +382,8 @@ static inline void list_splice_tail_init_rcu(struct list_head *list, * as long as the traversal is guarded by rcu_read_lock(). */ #define list_for_each_entry_rcu(pos, head, member, cond...) \ - if (COUNT_VARGS(cond) != 0) { \ - __list_check_rcu_cond(0, ## cond); \ - } else { \ - __list_check_rcu(); \ - } \ - for (pos = list_entry_rcu((head)->next, typeof(*pos), member); \ + for (__list_check_rcu(cond), \ + pos = list_entry_rcu((head)->next, typeof(*pos), member); \ &pos->member != (head); \ pos = list_entry_rcu(pos->member.next, typeof(*pos), member))
@@ -649,12 +656,8 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n, * as long as the traversal is guarded by rcu_read_lock(). */ #define hlist_for_each_entry_rcu(pos, head, member, cond...) \ - if (COUNT_VARGS(cond) != 0) { \ - __list_check_rcu_cond(0, ## cond); \ - } else { \ - __list_check_rcu(); \ - } \ - for (pos = hlist_entry_safe (rcu_dereference_raw(hlist_first_rcu(head)),\ + for (__list_check_rcu(cond), \ + pos = hlist_entry_safe (rcu_dereference_raw(hlist_first_rcu(head)),\ typeof(*(pos)), member); \ pos; \ pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(\
--
2.22.0.rc1.311.g5d7573a151-goog