d97b078182
To de-offload callback processing back onto a CPU, it is necessary to clear SEGCBLIST_OFFLOAD and notify the nocb CB kthread, which will then clear its own bit flag and go to sleep to stop handling callbacks. This commit makes that change. It will also be necessary to notify the nocb GP kthread in this same way, which is the subject of a follow-on commit. Cc: Josh Triplett <josh@joshtriplett.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Neeraj Upadhyay <neeraju@codeaurora.org> Cc: Thomas Gleixner <tglx@linutronix.de> Inspired-by: Paul E. McKenney <paulmck@kernel.org> Tested-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> [ paulmck: Add export per kernel test robot feedback. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
136 lines
4.4 KiB
C
136 lines
4.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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* RCU segmented callback lists, internal-to-rcu header file
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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.ibm.com>
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*/
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#include <linux/rcu_segcblist.h>
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/* Return number of callbacks in the specified 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 READ_ONCE(rclp->len);
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}
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/* Return number of callbacks in segmented callback list by summing seglen. */
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long rcu_segcblist_n_segment_cbs(struct rcu_segcblist *rsclp);
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void rcu_cblist_init(struct rcu_cblist *rclp);
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void rcu_cblist_enqueue(struct rcu_cblist *rclp, struct rcu_head *rhp);
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void rcu_cblist_flush_enqueue(struct rcu_cblist *drclp,
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struct rcu_cblist *srclp,
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struct rcu_head *rhp);
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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 !READ_ONCE(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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#ifdef CONFIG_RCU_NOCB_CPU
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return atomic_long_read(&rsclp->len);
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#else
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return READ_ONCE(rsclp->len);
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#endif
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}
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static inline void rcu_segcblist_set_flags(struct rcu_segcblist *rsclp,
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int flags)
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{
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rsclp->flags |= flags;
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}
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static inline void rcu_segcblist_clear_flags(struct rcu_segcblist *rsclp,
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int flags)
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{
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rsclp->flags &= ~flags;
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}
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static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,
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int flags)
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{
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return READ_ONCE(rsclp->flags) & flags;
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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 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 rcu_segcblist_test_flags(rsclp, SEGCBLIST_ENABLED);
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}
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/* Is the specified rcu_segcblist offloaded? */
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static inline bool rcu_segcblist_is_offloaded(struct rcu_segcblist *rsclp)
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{
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if (IS_ENABLED(CONFIG_RCU_NOCB_CPU)) {
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/*
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* Complete de-offloading happens only when SEGCBLIST_SOFTIRQ_ONLY
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* is set.
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*/
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if (!rcu_segcblist_test_flags(rsclp, SEGCBLIST_SOFTIRQ_ONLY))
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return true;
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}
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return false;
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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 !READ_ONCE(*READ_ONCE(rsclp->tails[seg]));
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}
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void rcu_segcblist_inc_len(struct rcu_segcblist *rsclp);
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void rcu_segcblist_add_len(struct rcu_segcblist *rsclp, long v);
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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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void rcu_segcblist_offload(struct rcu_segcblist *rsclp, bool offload);
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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_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_nextgp(struct rcu_segcblist *rsclp, unsigned long *lp);
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void rcu_segcblist_enqueue(struct rcu_segcblist *rsclp,
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struct rcu_head *rhp);
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bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp,
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struct rcu_head *rhp);
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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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void rcu_segcblist_merge(struct rcu_segcblist *dst_rsclp,
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struct rcu_segcblist *src_rsclp);
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