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rcu: Open-code the rcu_cblist_empty() function

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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>
This commit is contained in:
Paul E. McKenney
2017-05-02 08:18:40 -07:00
parent 98059b9861
commit 8ef0f37efb
3 changed files with 7 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
kernel/rcu/rcu_segcblist.h
View File

@@ -22,12 +22,6 @@
#include <linux/rcu_segcblist.h> #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. */ /* Return number of callbacks in simple callback list. */
static inline long rcu_cblist_n_cbs(struct rcu_cblist *rclp) 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) 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; return rclp->tail;
} }

9
kernel/rcu/tree.c
View File

@@ -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. */ /* First adopt the ready-to-invoke callbacks, then the done ones. */
rcu_segcblist_insert_done_cbs(&rdp->cblist, &rsp->orphan_done); 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); 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) != WARN_ON_ONCE(rcu_segcblist_empty(&rdp->cblist) !=
!rcu_segcblist_n_cbs(&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); local_irq_save(flags);
count = -rcu_cblist_n_cbs(&rcl); count = -rcu_cblist_n_cbs(&rcl);
trace_rcu_batch_end(rsp->name, count, !rcu_cblist_empty(&rcl), trace_rcu_batch_end(rsp->name, count, !!rcl.head, need_resched(),
need_resched(), is_idle_task(current), is_idle_task(current), rcu_is_callbacks_kthread());
rcu_is_callbacks_kthread());
/* Update counts and requeue any remaining callbacks. */ /* Update counts and requeue any remaining callbacks. */
rcu_segcblist_insert_done_cbs(&rdp->cblist, &rcl); rcu_segcblist_insert_done_cbs(&rdp->cblist, &rcl);

4
kernel/rcu/tree_plugin.h
View File

@@ -1942,12 +1942,12 @@ static bool __maybe_unused rcu_nocb_adopt_orphan_cbs(struct rcu_state *rsp,
return false; return false;
/* First, enqueue the donelist, if any. This preserves CB ordering. */ /* 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), __call_rcu_nocb_enqueue(rdp, rcu_cblist_head(&rsp->orphan_done),
rcu_cblist_tail(&rsp->orphan_done), rcu_cblist_tail(&rsp->orphan_done),
ql, qll, flags); 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), __call_rcu_nocb_enqueue(rdp, rcu_cblist_head(&rsp->orphan_pend),
rcu_cblist_tail(&rsp->orphan_pend), rcu_cblist_tail(&rsp->orphan_pend),
ql, qll, flags); ql, qll, flags);