![Paul E. McKenney](/assets/img/avatar_default.png)
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>
177 lines
5.9 KiB
C
177 lines
5.9 KiB
C
/*
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* RCU segmented callback lists, internal-to-rcu header file
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, you can access it online at
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* http://www.gnu.org/licenses/gpl-2.0.html.
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*
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* Copyright IBM Corporation, 2017
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*
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* Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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*/
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#include <linux/rcu_segcblist.h>
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/* Return number of callbacks in simple callback list. */
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static inline long rcu_cblist_n_cbs(struct rcu_cblist *rclp)
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{
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return rclp->len;
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}
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/* Return number of lazy callbacks in simple callback list. */
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static inline long rcu_cblist_n_lazy_cbs(struct rcu_cblist *rclp)
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{
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return rclp->len_lazy;
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}
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/*
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* Account for the fact that a previously dequeued callback turned out
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* to be marked as lazy.
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*/
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static inline void rcu_cblist_dequeued_lazy(struct rcu_cblist *rclp)
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{
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rclp->len_lazy--;
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}
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/*
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* Interim function to return rcu_cblist head pointer. Longer term, the
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* rcu_cblist will be used more pervasively, removing the need for this
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* function.
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*/
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static inline struct rcu_head *rcu_cblist_head(struct rcu_cblist *rclp)
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{
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return rclp->head;
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}
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/*
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* Interim function to return rcu_cblist head pointer. Longer term, the
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* rcu_cblist will be used more pervasively, removing the need for this
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* function.
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*/
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static inline struct rcu_head **rcu_cblist_tail(struct rcu_cblist *rclp)
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{
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WARN_ON_ONCE(!rclp->head);
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return rclp->tail;
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}
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void rcu_cblist_init(struct rcu_cblist *rclp);
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long rcu_cblist_count_cbs(struct rcu_cblist *rclp, long lim);
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struct rcu_head *rcu_cblist_dequeue(struct rcu_cblist *rclp);
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/*
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* Is the specified rcu_segcblist structure empty?
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*
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* But careful! The fact that the ->head field is NULL does not
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* necessarily imply that there are no callbacks associated with
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* this structure. When callbacks are being invoked, they are
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* removed as a group. If callback invocation must be preempted,
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* the remaining callbacks will be added back to the list. Either
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* way, the counts are updated later.
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*
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* So it is often the case that rcu_segcblist_n_cbs() should be used
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* instead.
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*/
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static inline bool rcu_segcblist_empty(struct rcu_segcblist *rsclp)
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{
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return !rsclp->head;
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}
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/* Return number of callbacks in segmented callback list. */
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static inline long rcu_segcblist_n_cbs(struct rcu_segcblist *rsclp)
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{
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return READ_ONCE(rsclp->len);
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}
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/* Return number of lazy callbacks in segmented callback list. */
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static inline long rcu_segcblist_n_lazy_cbs(struct rcu_segcblist *rsclp)
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{
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return rsclp->len_lazy;
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}
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/* Return number of lazy callbacks in segmented callback list. */
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static inline long rcu_segcblist_n_nonlazy_cbs(struct rcu_segcblist *rsclp)
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{
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return rsclp->len - rsclp->len_lazy;
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}
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/*
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* Is the specified rcu_segcblist enabled, for example, not corresponding
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* to an offline or callback-offloaded CPU?
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*/
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static inline bool rcu_segcblist_is_enabled(struct rcu_segcblist *rsclp)
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{
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return !!rsclp->tails[RCU_NEXT_TAIL];
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}
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/*
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* Are all segments following the specified segment of the specified
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* rcu_segcblist structure empty of callbacks? (The specified
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* segment might well contain callbacks.)
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*/
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static inline bool rcu_segcblist_restempty(struct rcu_segcblist *rsclp, int seg)
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{
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return !*rsclp->tails[seg];
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}
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/*
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* Interim function to return rcu_segcblist head pointer. Longer term, the
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* rcu_segcblist will be used more pervasively, removing the need for this
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* function.
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*/
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static inline struct rcu_head *rcu_segcblist_head(struct rcu_segcblist *rsclp)
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{
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return rsclp->head;
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}
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/*
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* Interim function to return rcu_segcblist head pointer. Longer term, the
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* rcu_segcblist will be used more pervasively, removing the need for this
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* function.
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*/
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static inline struct rcu_head **rcu_segcblist_tail(struct rcu_segcblist *rsclp)
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{
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WARN_ON_ONCE(rcu_segcblist_empty(rsclp));
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return rsclp->tails[RCU_NEXT_TAIL];
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}
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void rcu_segcblist_init(struct rcu_segcblist *rsclp);
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void rcu_segcblist_disable(struct rcu_segcblist *rsclp);
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bool rcu_segcblist_segempty(struct rcu_segcblist *rsclp, int seg);
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bool rcu_segcblist_ready_cbs(struct rcu_segcblist *rsclp);
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bool rcu_segcblist_pend_cbs(struct rcu_segcblist *rsclp);
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struct rcu_head *rcu_segcblist_dequeue(struct rcu_segcblist *rsclp);
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void rcu_segcblist_dequeued_lazy(struct rcu_segcblist *rsclp);
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struct rcu_head *rcu_segcblist_first_cb(struct rcu_segcblist *rsclp);
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struct rcu_head *rcu_segcblist_first_pend_cb(struct rcu_segcblist *rsclp);
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bool rcu_segcblist_new_cbs(struct rcu_segcblist *rsclp);
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void rcu_segcblist_enqueue(struct rcu_segcblist *rsclp,
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struct rcu_head *rhp, bool lazy);
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bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp,
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struct rcu_head *rhp, bool lazy);
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void rcu_segcblist_extract_count(struct rcu_segcblist *rsclp,
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struct rcu_cblist *rclp);
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void rcu_segcblist_extract_done_cbs(struct rcu_segcblist *rsclp,
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struct rcu_cblist *rclp);
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void rcu_segcblist_extract_pend_cbs(struct rcu_segcblist *rsclp,
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struct rcu_cblist *rclp);
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void rcu_segcblist_insert_count(struct rcu_segcblist *rsclp,
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struct rcu_cblist *rclp);
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void rcu_segcblist_insert_done_cbs(struct rcu_segcblist *rsclp,
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struct rcu_cblist *rclp);
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void rcu_segcblist_insert_pend_cbs(struct rcu_segcblist *rsclp,
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struct rcu_cblist *rclp);
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void rcu_segcblist_advance(struct rcu_segcblist *rsclp, unsigned long seq);
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bool rcu_segcblist_accelerate(struct rcu_segcblist *rsclp, unsigned long seq);
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bool rcu_segcblist_future_gp_needed(struct rcu_segcblist *rsclp,
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unsigned long seq);
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