[PATCH tip/core/rcu 0/3] Open-code trivial rcu_cblist accessors

[PATCH tip/core/rcu 0/3] Open-code trivial rcu_cblist accessors

[Paul E. McKenney]

Hello!

And this series open-codes trivial rcu_cblist structure accessors:

1.	Open-code rcu_cblist_empty(p) as !p->head.

2.	Open-code rcu_cblist_n_cbs(p) as p->len.

3.	Open-code rcu_cblist_n_lazy_cbs(p) as p->len_lazy.


							Thanx, Paul

------------------------------------------------------------------------

 rcu_segcblist.h |   20 +-------------------
 tree.c          |   20 +++++++++-----------
 tree_plugin.h   |    8 ++++----
 tree_trace.c    |    4 ++--
 4 files changed, 16 insertions(+), 36 deletions(-)

[PATCH tip/core/rcu 1/3] rcu: Open-code the rcu_cblist_empty() function

[Paul E. McKenney]

Because the rcu_cblist_empty() just samples the ->head pointer, and
because the rcu_cblist structure is quite straightforward, it makes
sense to open-code rcu_cblist_empty(p) as !p->head, cutting out a
level of indirection.  This commit makes this change.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
---
 kernel/rcu/rcu_segcblist.h | 8 +-------
 kernel/rcu/tree.c          | 9 ++++-----
 kernel/rcu/tree_plugin.h   | 4 ++--
 3 files changed, 7 insertions(+), 14 deletions(-)

diff --git a/kernel/rcu/rcu_segcblist.h b/kernel/rcu/rcu_segcblist.h
index 86bc1101b806..7d18d41f0116 100644
--- a/kernel/rcu/rcu_segcblist.h
+++ b/kernel/rcu/rcu_segcblist.h
@@ -22,12 +22,6 @@
 
 #include <linux/rcu_segcblist.h>
 
-/* Is simple callback list empty? */
-static inline bool rcu_cblist_empty(struct rcu_cblist *rclp)
-{
-	return !rclp->head;
-}
-
 /* Return number of callbacks in simple callback list. */
 static inline long rcu_cblist_n_cbs(struct rcu_cblist *rclp)
 {
@@ -66,7 +60,7 @@ static inline struct rcu_head *rcu_cblist_head(struct rcu_cblist *rclp)
  */
 static inline struct rcu_head **rcu_cblist_tail(struct rcu_cblist *rclp)
 {
-	WARN_ON_ONCE(rcu_cblist_empty(rclp));
+	WARN_ON_ONCE(!rclp->head);
 	return rclp->tail;
 }
 
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 91fff49d5869..35152414760d 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2647,9 +2647,9 @@ static void rcu_adopt_orphan_cbs(struct rcu_state *rsp, unsigned long flags)
 
 	/* First adopt the ready-to-invoke callbacks, then the done ones. */
 	rcu_segcblist_insert_done_cbs(&rdp->cblist, &rsp->orphan_done);
-	WARN_ON_ONCE(!rcu_cblist_empty(&rsp->orphan_done));
+	WARN_ON_ONCE(rsp->orphan_done.head);
 	rcu_segcblist_insert_pend_cbs(&rdp->cblist, &rsp->orphan_pend);
-	WARN_ON_ONCE(!rcu_cblist_empty(&rsp->orphan_pend));
+	WARN_ON_ONCE(rsp->orphan_pend.head);
 	WARN_ON_ONCE(rcu_segcblist_empty(&rdp->cblist) !=
 		     !rcu_segcblist_n_cbs(&rdp->cblist));
 }
@@ -2800,9 +2800,8 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
 
 	local_irq_save(flags);
 	count = -rcu_cblist_n_cbs(&rcl);
-	trace_rcu_batch_end(rsp->name, count, !rcu_cblist_empty(&rcl),
-			    need_resched(), is_idle_task(current),
-			    rcu_is_callbacks_kthread());
+	trace_rcu_batch_end(rsp->name, count, !!rcl.head, need_resched(),
+			    is_idle_task(current), rcu_is_callbacks_kthread());
 
 	/* Update counts and requeue any remaining callbacks. */
 	rcu_segcblist_insert_done_cbs(&rdp->cblist, &rcl);
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 7f1d677a2a25..6b4b1f8a272d 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1942,12 +1942,12 @@ static bool __maybe_unused rcu_nocb_adopt_orphan_cbs(struct rcu_state *rsp,
 		return false;
 
 	/* First, enqueue the donelist, if any.  This preserves CB ordering. */
-	if (!rcu_cblist_empty(&rsp->orphan_done)) {
+	if (rsp->orphan_done.head) {
 		__call_rcu_nocb_enqueue(rdp, rcu_cblist_head(&rsp->orphan_done),
 					rcu_cblist_tail(&rsp->orphan_done),
 					ql, qll, flags);
 	}
-	if (!rcu_cblist_empty(&rsp->orphan_pend)) {
+	if (rsp->orphan_pend.head) {
 		__call_rcu_nocb_enqueue(rdp, rcu_cblist_head(&rsp->orphan_pend),
 					rcu_cblist_tail(&rsp->orphan_pend),
 					ql, qll, flags);
-- 
2.5.2

[PATCH tip/core/rcu 2/3] rcu: Open-code the rcu_cblist_n_cbs() function

[Paul E. McKenney]

Because the rcu_cblist_n_cbs() just samples the ->len counter, and
because the rcu_cblist structure is quite straightforward, it makes
sense to open-code rcu_cblist_n_cbs(p) as p->len, cutting out a level
of indirection.  This commit makes this change.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
---
 kernel/rcu/rcu_segcblist.h | 6 ------
 kernel/rcu/tree.c          | 9 ++++-----
 kernel/rcu/tree_plugin.h   | 2 +-
 kernel/rcu/tree_trace.c    | 2 +-
 4 files changed, 6 insertions(+), 13 deletions(-)

diff --git a/kernel/rcu/rcu_segcblist.h b/kernel/rcu/rcu_segcblist.h
index 7d18d41f0116..424a6b230921 100644
--- a/kernel/rcu/rcu_segcblist.h
+++ b/kernel/rcu/rcu_segcblist.h
@@ -22,12 +22,6 @@
 
 #include <linux/rcu_segcblist.h>
 
-/* Return number of callbacks in simple callback list. */
-static inline long rcu_cblist_n_cbs(struct rcu_cblist *rclp)
-{
-	return rclp->len;
-}
-
 /* Return number of lazy callbacks in simple callback list. */
 static inline long rcu_cblist_n_lazy_cbs(struct rcu_cblist *rclp)
 {
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 35152414760d..942d529fccbc 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2633,9 +2633,8 @@ static void rcu_adopt_orphan_cbs(struct rcu_state *rsp, unsigned long flags)
 		return;
 
 	/* Do the accounting first. */
-	rdp->n_cbs_adopted += rcu_cblist_n_cbs(&rsp->orphan_done);
-	if (rcu_cblist_n_lazy_cbs(&rsp->orphan_done) !=
-	    rcu_cblist_n_cbs(&rsp->orphan_done))
+	rdp->n_cbs_adopted += rsp->orphan_done.len;
+	if (rcu_cblist_n_lazy_cbs(&rsp->orphan_done) != rsp->orphan_done.len)
 		rcu_idle_count_callbacks_posted();
 	rcu_segcblist_insert_count(&rdp->cblist, &rsp->orphan_done);
 
@@ -2792,14 +2791,14 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
 		 * Stop only if limit reached and CPU has something to do.
 		 * Note: The rcl structure counts down from zero.
 		 */
-		if (-rcu_cblist_n_cbs(&rcl) >= bl &&
+		if (-rcl.len >= bl &&
 		    (need_resched() ||
 		     (!is_idle_task(current) && !rcu_is_callbacks_kthread())))
 			break;
 	}
 
 	local_irq_save(flags);
-	count = -rcu_cblist_n_cbs(&rcl);
+	count = -rcl.len;
 	trace_rcu_batch_end(rsp->name, count, !!rcl.head, need_resched(),
 			    is_idle_task(current), rcu_is_callbacks_kthread());
 
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 6b4b1f8a272d..7ebe357df155 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1934,7 +1934,7 @@ static bool __maybe_unused rcu_nocb_adopt_orphan_cbs(struct rcu_state *rsp,
 						     struct rcu_data *rdp,
 						     unsigned long flags)
 {
-	long ql = rcu_cblist_n_cbs(&rsp->orphan_done);
+	long ql = rsp->orphan_done.len;
 	long qll = rcu_cblist_n_lazy_cbs(&rsp->orphan_done);
 
 	/* If this is not a no-CBs CPU, tell the caller to do it the old way. */
diff --git a/kernel/rcu/tree_trace.c b/kernel/rcu/tree_trace.c
index 30c5bf89ee58..b7743aa2965f 100644
--- a/kernel/rcu/tree_trace.c
+++ b/kernel/rcu/tree_trace.c
@@ -278,7 +278,7 @@ static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
 		   rsp->n_force_qs - rsp->n_force_qs_ngp,
 		   READ_ONCE(rsp->n_force_qs_lh),
 		   rcu_cblist_n_lazy_cbs(&rsp->orphan_done),
-		   rcu_cblist_n_cbs(&rsp->orphan_done));
+		   rsp->orphan_done.len);
 	for (rnp = &rsp->node[0]; rnp - &rsp->node[0] < rcu_num_nodes; rnp++) {
 		if (rnp->level != level) {
 			seq_puts(m, "\n");
-- 
2.5.2

[PATCH tip/core/rcu 3/3] rcu: Open-code the rcu_cblist_n_lazy_cbs() function

[Paul E. McKenney]

Because the rcu_cblist_n_lazy_cbs() just samples the ->len_lazy counter,
and because the rcu_cblist structure is quite straightforward, it makes
sense to open-code rcu_cblist_n_lazy_cbs(p) as p->len_lazy, cutting out
a level of indirection.  This commit makes this change.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
---
 kernel/rcu/rcu_segcblist.h | 6 ------
 kernel/rcu/tree.c          | 2 +-
 kernel/rcu/tree_plugin.h   | 2 +-
 kernel/rcu/tree_trace.c    | 2 +-
 4 files changed, 3 insertions(+), 9 deletions(-)

diff --git a/kernel/rcu/rcu_segcblist.h b/kernel/rcu/rcu_segcblist.h
index 424a6b230921..6e36e36478cd 100644
--- a/kernel/rcu/rcu_segcblist.h
+++ b/kernel/rcu/rcu_segcblist.h
@@ -22,12 +22,6 @@
 
 #include <linux/rcu_segcblist.h>
 
-/* Return number of lazy callbacks in simple callback list. */
-static inline long rcu_cblist_n_lazy_cbs(struct rcu_cblist *rclp)
-{
-	return rclp->len_lazy;
-}
-
 /*
  * Account for the fact that a previously dequeued callback turned out
  * to be marked as lazy.
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 942d529fccbc..1205c8ad138a 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2634,7 +2634,7 @@ static void rcu_adopt_orphan_cbs(struct rcu_state *rsp, unsigned long flags)
 
 	/* Do the accounting first. */
 	rdp->n_cbs_adopted += rsp->orphan_done.len;
-	if (rcu_cblist_n_lazy_cbs(&rsp->orphan_done) != rsp->orphan_done.len)
+	if (rsp->orphan_done.len_lazy != rsp->orphan_done.len)
 		rcu_idle_count_callbacks_posted();
 	rcu_segcblist_insert_count(&rdp->cblist, &rsp->orphan_done);
 
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 7ebe357df155..c9a48657512a 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1935,7 +1935,7 @@ static bool __maybe_unused rcu_nocb_adopt_orphan_cbs(struct rcu_state *rsp,
 						     unsigned long flags)
 {
 	long ql = rsp->orphan_done.len;
-	long qll = rcu_cblist_n_lazy_cbs(&rsp->orphan_done);
+	long qll = rsp->orphan_done.len_lazy;
 
 	/* If this is not a no-CBs CPU, tell the caller to do it the old way. */
 	if (!rcu_is_nocb_cpu(smp_processor_id()))
diff --git a/kernel/rcu/tree_trace.c b/kernel/rcu/tree_trace.c
index b7743aa2965f..6cea17a1ea30 100644
--- a/kernel/rcu/tree_trace.c
+++ b/kernel/rcu/tree_trace.c
@@ -277,7 +277,7 @@ static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
 		   rsp->n_force_qs, rsp->n_force_qs_ngp,
 		   rsp->n_force_qs - rsp->n_force_qs_ngp,
 		   READ_ONCE(rsp->n_force_qs_lh),
-		   rcu_cblist_n_lazy_cbs(&rsp->orphan_done),
+		   rsp->orphan_done.len_lazy,
 		   rsp->orphan_done.len);
 	for (rnp = &rsp->node[0]; rnp - &rsp->node[0] < rcu_num_nodes; rnp++) {
 		if (rnp->level != level) {
-- 
2.5.2

Re: [PATCH tip/core/rcu 0/3] Open-code trivial rcu_cblist accessors

[Ingo Molnar]

* Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote:

> Hello!
> 
> And this series open-codes trivial rcu_cblist structure accessors:
> 
> 1.	Open-code rcu_cblist_empty(p) as !p->head.
> 
> 2.	Open-code rcu_cblist_n_cbs(p) as p->len.
> 
> 3.	Open-code rcu_cblist_n_lazy_cbs(p) as p->len_lazy.
> 
> 
> 							Thanx, Paul
> 
> ------------------------------------------------------------------------
> 
>  rcu_segcblist.h |   20 +-------------------
>  tree.c          |   20 +++++++++-----------
>  tree_plugin.h   |    8 ++++----
>  tree_trace.c    |    4 ++--
>  4 files changed, 16 insertions(+), 36 deletions(-)

Ok, these all look good to me.

Thanks,

	Ingo

Re: [PATCH tip/core/rcu 0/3] Open-code trivial rcu_cblist accessors

[Paul E. McKenney]

On Tue, May 02, 2017 at 06:47:10PM +0200, Ingo Molnar wrote:
> 
> * Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote:
> 
> > Hello!
> > 
> > And this series open-codes trivial rcu_cblist structure accessors:
> > 
> > 1.	Open-code rcu_cblist_empty(p) as !p->head.
> > 
> > 2.	Open-code rcu_cblist_n_cbs(p) as p->len.
> > 
> > 3.	Open-code rcu_cblist_n_lazy_cbs(p) as p->len_lazy.
> > 
> > 
> > 							Thanx, Paul
> > 
> > ------------------------------------------------------------------------
> > 
> >  rcu_segcblist.h |   20 +-------------------
> >  tree.c          |   20 +++++++++-----------
> >  tree_plugin.h   |    8 ++++----
> >  tree_trace.c    |    4 ++--
> >  4 files changed, 16 insertions(+), 36 deletions(-)
> 
> Ok, these all look good to me.

Whew!  ;-)

							Thanx, Paul