diff options
author | Ingo Molnar <mingo@kernel.org> | 2017-05-03 08:00:14 +0200 |
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committer | Ingo Molnar <mingo@kernel.org> | 2017-05-03 08:00:14 +0200 |
commit | 20652ed6e44f4963281b65209b917be86ac6765b (patch) | |
tree | b9a71f3445203169c7deda78e8ea971f4cba01c0 /kernel | |
parent | b5fe223a4bd0217a657ff084e48752c367a8a55f (diff) | |
parent | 933dfbd7c437bbbf65caae785dfa105fbfaa8485 (diff) | |
download | op-kernel-dev-20652ed6e44f4963281b65209b917be86ac6765b.zip op-kernel-dev-20652ed6e44f4963281b65209b917be86ac6765b.tar.gz |
Merge branch 'for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu
Pull RCU fixes from Paul E. McKenney:
"This series adds a pair of commits that move function definitions
from include/linux/rcu_segcblist.h to new kernel/rcu/rcu_segcblist.h
and kernel/rcu/rcu_segcblist.c files, thus greatly decreasing the
size of the externally visible include/linux/rcu_segcblist.h file."
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/rcu/Makefile | 1 | ||||
-rw-r--r-- | kernel/rcu/rcu_segcblist.c | 505 | ||||
-rw-r--r-- | kernel/rcu/rcu_segcblist.h | 164 | ||||
-rw-r--r-- | kernel/rcu/srcutiny.c | 1 | ||||
-rw-r--r-- | kernel/rcu/srcutree.c | 1 | ||||
-rw-r--r-- | kernel/rcu/tree.c | 18 | ||||
-rw-r--r-- | kernel/rcu/tree.h | 3 | ||||
-rw-r--r-- | kernel/rcu/tree_plugin.h | 8 | ||||
-rw-r--r-- | kernel/rcu/tree_trace.c | 4 |
9 files changed, 688 insertions, 17 deletions
diff --git a/kernel/rcu/Makefile b/kernel/rcu/Makefile index 158e659..23803c7 100644 --- a/kernel/rcu/Makefile +++ b/kernel/rcu/Makefile @@ -12,3 +12,4 @@ obj-$(CONFIG_TREE_RCU) += tree.o obj-$(CONFIG_PREEMPT_RCU) += tree.o obj-$(CONFIG_TREE_RCU_TRACE) += tree_trace.o obj-$(CONFIG_TINY_RCU) += tiny.o +obj-$(CONFIG_RCU_NEED_SEGCBLIST) += rcu_segcblist.o diff --git a/kernel/rcu/rcu_segcblist.c b/kernel/rcu/rcu_segcblist.c new file mode 100644 index 0000000..2b62a38 --- /dev/null +++ b/kernel/rcu/rcu_segcblist.c @@ -0,0 +1,505 @@ +/* + * RCU segmented callback lists, function definitions + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, you can access it online at + * http://www.gnu.org/licenses/gpl-2.0.html. + * + * Copyright IBM Corporation, 2017 + * + * Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com> + */ + +#include <linux/types.h> +#include <linux/kernel.h> +#include <linux/interrupt.h> + +#include "rcu_segcblist.h" + +/* Initialize simple callback list. */ +void rcu_cblist_init(struct rcu_cblist *rclp) +{ + rclp->head = NULL; + rclp->tail = &rclp->head; + rclp->len = 0; + rclp->len_lazy = 0; +} + +/* + * Debug function to actually count the number of callbacks. + * If the number exceeds the limit specified, return -1. + */ +long rcu_cblist_count_cbs(struct rcu_cblist *rclp, long lim) +{ + int cnt = 0; + struct rcu_head **rhpp = &rclp->head; + + for (;;) { + if (!*rhpp) + return cnt; + if (++cnt > lim) + return -1; + rhpp = &(*rhpp)->next; + } +} + +/* + * Dequeue the oldest rcu_head structure from the specified callback + * list. This function assumes that the callback is non-lazy, but + * the caller can later invoke rcu_cblist_dequeued_lazy() if it + * finds otherwise (and if it cares about laziness). This allows + * different users to have different ways of determining laziness. + */ +struct rcu_head *rcu_cblist_dequeue(struct rcu_cblist *rclp) +{ + struct rcu_head *rhp; + + rhp = rclp->head; + if (!rhp) + return NULL; + rclp->len--; + rclp->head = rhp->next; + if (!rclp->head) + rclp->tail = &rclp->head; + return rhp; +} + +/* + * Initialize an rcu_segcblist structure. + */ +void rcu_segcblist_init(struct rcu_segcblist *rsclp) +{ + int i; + + BUILD_BUG_ON(RCU_NEXT_TAIL + 1 != ARRAY_SIZE(rsclp->gp_seq)); + BUILD_BUG_ON(ARRAY_SIZE(rsclp->tails) != ARRAY_SIZE(rsclp->gp_seq)); + rsclp->head = NULL; + for (i = 0; i < RCU_CBLIST_NSEGS; i++) + rsclp->tails[i] = &rsclp->head; + rsclp->len = 0; + rsclp->len_lazy = 0; +} + +/* + * Disable the specified rcu_segcblist structure, so that callbacks can + * no longer be posted to it. This structure must be empty. + */ +void rcu_segcblist_disable(struct rcu_segcblist *rsclp) +{ + WARN_ON_ONCE(!rcu_segcblist_empty(rsclp)); + WARN_ON_ONCE(rcu_segcblist_n_cbs(rsclp)); + WARN_ON_ONCE(rcu_segcblist_n_lazy_cbs(rsclp)); + rsclp->tails[RCU_NEXT_TAIL] = NULL; +} + +/* + * Is the specified segment of the specified rcu_segcblist structure + * empty of callbacks? + */ +bool rcu_segcblist_segempty(struct rcu_segcblist *rsclp, int seg) +{ + if (seg == RCU_DONE_TAIL) + return &rsclp->head == rsclp->tails[RCU_DONE_TAIL]; + return rsclp->tails[seg - 1] == rsclp->tails[seg]; +} + +/* + * Does the specified rcu_segcblist structure contain callbacks that + * are ready to be invoked? + */ +bool rcu_segcblist_ready_cbs(struct rcu_segcblist *rsclp) +{ + return rcu_segcblist_is_enabled(rsclp) && + &rsclp->head != rsclp->tails[RCU_DONE_TAIL]; +} + +/* + * Does the specified rcu_segcblist structure contain callbacks that + * are still pending, that is, not yet ready to be invoked? + */ +bool rcu_segcblist_pend_cbs(struct rcu_segcblist *rsclp) +{ + return rcu_segcblist_is_enabled(rsclp) && + !rcu_segcblist_restempty(rsclp, RCU_DONE_TAIL); +} + +/* + * Dequeue and return the first ready-to-invoke callback. If there + * are no ready-to-invoke callbacks, return NULL. Disables interrupts + * to avoid interference. Does not protect from interference from other + * CPUs or tasks. + */ +struct rcu_head *rcu_segcblist_dequeue(struct rcu_segcblist *rsclp) +{ + unsigned long flags; + int i; + struct rcu_head *rhp; + + local_irq_save(flags); + if (!rcu_segcblist_ready_cbs(rsclp)) { + local_irq_restore(flags); + return NULL; + } + rhp = rsclp->head; + BUG_ON(!rhp); + rsclp->head = rhp->next; + for (i = RCU_DONE_TAIL; i < RCU_CBLIST_NSEGS; i++) { + if (rsclp->tails[i] != &rhp->next) + break; + rsclp->tails[i] = &rsclp->head; + } + smp_mb(); /* Dequeue before decrement for rcu_barrier(). */ + WRITE_ONCE(rsclp->len, rsclp->len - 1); + local_irq_restore(flags); + return rhp; +} + +/* + * Account for the fact that a previously dequeued callback turned out + * to be marked as lazy. + */ +void rcu_segcblist_dequeued_lazy(struct rcu_segcblist *rsclp) +{ + unsigned long flags; + + local_irq_save(flags); + rsclp->len_lazy--; + local_irq_restore(flags); +} + +/* + * Return a pointer to the first callback in the specified rcu_segcblist + * structure. This is useful for diagnostics. + */ +struct rcu_head *rcu_segcblist_first_cb(struct rcu_segcblist *rsclp) +{ + if (rcu_segcblist_is_enabled(rsclp)) + return rsclp->head; + return NULL; +} + +/* + * Return a pointer to the first pending callback in the specified + * rcu_segcblist structure. This is useful just after posting a given + * callback -- if that callback is the first pending callback, then + * you cannot rely on someone else having already started up the required + * grace period. + */ +struct rcu_head *rcu_segcblist_first_pend_cb(struct rcu_segcblist *rsclp) +{ + if (rcu_segcblist_is_enabled(rsclp)) + return *rsclp->tails[RCU_DONE_TAIL]; + return NULL; +} + +/* + * Does the specified rcu_segcblist structure contain callbacks that + * have not yet been processed beyond having been posted, that is, + * does it contain callbacks in its last segment? + */ +bool rcu_segcblist_new_cbs(struct rcu_segcblist *rsclp) +{ + return rcu_segcblist_is_enabled(rsclp) && + !rcu_segcblist_restempty(rsclp, RCU_NEXT_READY_TAIL); +} + +/* + * Enqueue the specified callback onto the specified rcu_segcblist + * structure, updating accounting as needed. Note that the ->len + * field may be accessed locklessly, hence the WRITE_ONCE(). + * The ->len field is used by rcu_barrier() and friends to determine + * if it must post a callback on this structure, and it is OK + * for rcu_barrier() to sometimes post callbacks needlessly, but + * absolutely not OK for it to ever miss posting a callback. + */ +void rcu_segcblist_enqueue(struct rcu_segcblist *rsclp, + struct rcu_head *rhp, bool lazy) +{ + WRITE_ONCE(rsclp->len, rsclp->len + 1); /* ->len sampled locklessly. */ + if (lazy) + rsclp->len_lazy++; + smp_mb(); /* Ensure counts are updated before callback is enqueued. */ + rhp->next = NULL; + *rsclp->tails[RCU_NEXT_TAIL] = rhp; + rsclp->tails[RCU_NEXT_TAIL] = &rhp->next; +} + +/* + * Entrain the specified callback onto the specified rcu_segcblist at + * the end of the last non-empty segment. If the entire rcu_segcblist + * is empty, make no change, but return false. + * + * This is intended for use by rcu_barrier()-like primitives, -not- + * for normal grace-period use. IMPORTANT: The callback you enqueue + * will wait for all prior callbacks, NOT necessarily for a grace + * period. You have been warned. + */ +bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp, + struct rcu_head *rhp, bool lazy) +{ + int i; + + if (rcu_segcblist_n_cbs(rsclp) == 0) + return false; + WRITE_ONCE(rsclp->len, rsclp->len + 1); + if (lazy) + rsclp->len_lazy++; + smp_mb(); /* Ensure counts are updated before callback is entrained. */ + rhp->next = NULL; + for (i = RCU_NEXT_TAIL; i > RCU_DONE_TAIL; i--) + if (rsclp->tails[i] != rsclp->tails[i - 1]) + break; + *rsclp->tails[i] = rhp; + for (; i <= RCU_NEXT_TAIL; i++) + rsclp->tails[i] = &rhp->next; + return true; +} + +/* + * Extract only the counts from the specified rcu_segcblist structure, + * and place them in the specified rcu_cblist structure. This function + * supports both callback orphaning and invocation, hence the separation + * of counts and callbacks. (Callbacks ready for invocation must be + * orphaned and adopted separately from pending callbacks, but counts + * apply to all callbacks. Locking must be used to make sure that + * both orphaned-callbacks lists are consistent.) + */ +void rcu_segcblist_extract_count(struct rcu_segcblist *rsclp, + struct rcu_cblist *rclp) +{ + rclp->len_lazy += rsclp->len_lazy; + rclp->len += rsclp->len; + rsclp->len_lazy = 0; + WRITE_ONCE(rsclp->len, 0); /* ->len sampled locklessly. */ +} + +/* + * Extract only those callbacks ready to be invoked from the specified + * rcu_segcblist structure and place them in the specified rcu_cblist + * structure. + */ +void rcu_segcblist_extract_done_cbs(struct rcu_segcblist *rsclp, + struct rcu_cblist *rclp) +{ + int i; + + if (!rcu_segcblist_ready_cbs(rsclp)) + return; /* Nothing to do. */ + *rclp->tail = rsclp->head; + rsclp->head = *rsclp->tails[RCU_DONE_TAIL]; + *rsclp->tails[RCU_DONE_TAIL] = NULL; + rclp->tail = rsclp->tails[RCU_DONE_TAIL]; + for (i = RCU_CBLIST_NSEGS - 1; i >= RCU_DONE_TAIL; i--) + if (rsclp->tails[i] == rsclp->tails[RCU_DONE_TAIL]) + rsclp->tails[i] = &rsclp->head; +} + +/* + * Extract only those callbacks still pending (not yet ready to be + * invoked) from the specified rcu_segcblist structure and place them in + * the specified rcu_cblist structure. Note that this loses information + * about any callbacks that might have been partway done waiting for + * their grace period. Too bad! They will have to start over. + */ +void rcu_segcblist_extract_pend_cbs(struct rcu_segcblist *rsclp, + struct rcu_cblist *rclp) +{ + int i; + + if (!rcu_segcblist_pend_cbs(rsclp)) + return; /* Nothing to do. */ + *rclp->tail = *rsclp->tails[RCU_DONE_TAIL]; + rclp->tail = rsclp->tails[RCU_NEXT_TAIL]; + *rsclp->tails[RCU_DONE_TAIL] = NULL; + for (i = RCU_DONE_TAIL + 1; i < RCU_CBLIST_NSEGS; i++) + rsclp->tails[i] = rsclp->tails[RCU_DONE_TAIL]; +} + +/* + * Insert counts from the specified rcu_cblist structure in the + * specified rcu_segcblist structure. + */ +void rcu_segcblist_insert_count(struct rcu_segcblist *rsclp, + struct rcu_cblist *rclp) +{ + rsclp->len_lazy += rclp->len_lazy; + /* ->len sampled locklessly. */ + WRITE_ONCE(rsclp->len, rsclp->len + rclp->len); + rclp->len_lazy = 0; + rclp->len = 0; +} + +/* + * Move callbacks from the specified rcu_cblist to the beginning of the + * done-callbacks segment of the specified rcu_segcblist. + */ +void rcu_segcblist_insert_done_cbs(struct rcu_segcblist *rsclp, + struct rcu_cblist *rclp) +{ + int i; + + if (!rclp->head) + return; /* No callbacks to move. */ + *rclp->tail = rsclp->head; + rsclp->head = rclp->head; + for (i = RCU_DONE_TAIL; i < RCU_CBLIST_NSEGS; i++) + if (&rsclp->head == rsclp->tails[i]) + rsclp->tails[i] = rclp->tail; + else + break; + rclp->head = NULL; + rclp->tail = &rclp->head; +} + +/* + * Move callbacks from the specified rcu_cblist to the end of the + * new-callbacks segment of the specified rcu_segcblist. + */ +void rcu_segcblist_insert_pend_cbs(struct rcu_segcblist *rsclp, + struct rcu_cblist *rclp) +{ + if (!rclp->head) + return; /* Nothing to do. */ + *rsclp->tails[RCU_NEXT_TAIL] = rclp->head; + rsclp->tails[RCU_NEXT_TAIL] = rclp->tail; + rclp->head = NULL; + rclp->tail = &rclp->head; +} + +/* + * Advance the callbacks in the specified rcu_segcblist structure based + * on the current value passed in for the grace-period counter. + */ +void rcu_segcblist_advance(struct rcu_segcblist *rsclp, unsigned long seq) +{ + int i, j; + + WARN_ON_ONCE(!rcu_segcblist_is_enabled(rsclp)); + if (rcu_segcblist_restempty(rsclp, RCU_DONE_TAIL)) + return; + + /* + * Find all callbacks whose ->gp_seq numbers indicate that they + * are ready to invoke, and put them into the RCU_DONE_TAIL segment. + */ + for (i = RCU_WAIT_TAIL; i < RCU_NEXT_TAIL; i++) { + if (ULONG_CMP_LT(seq, rsclp->gp_seq[i])) + break; + rsclp->tails[RCU_DONE_TAIL] = rsclp->tails[i]; + } + + /* If no callbacks moved, nothing more need be done. */ + if (i == RCU_WAIT_TAIL) + return; + + /* Clean up tail pointers that might have been misordered above. */ + for (j = RCU_WAIT_TAIL; j < i; j++) + rsclp->tails[j] = rsclp->tails[RCU_DONE_TAIL]; + + /* + * Callbacks moved, so clean up the misordered ->tails[] pointers + * that now point into the middle of the list of ready-to-invoke + * callbacks. The overall effect is to copy down the later pointers + * into the gap that was created by the now-ready segments. + */ + for (j = RCU_WAIT_TAIL; i < RCU_NEXT_TAIL; i++, j++) { + if (rsclp->tails[j] == rsclp->tails[RCU_NEXT_TAIL]) + break; /* No more callbacks. */ + rsclp->tails[j] = rsclp->tails[i]; + rsclp->gp_seq[j] = rsclp->gp_seq[i]; + } +} + +/* + * "Accelerate" callbacks based on more-accurate grace-period information. + * The reason for this is that RCU does not synchronize the beginnings and + * ends of grace periods, and that callbacks are posted locally. This in + * turn means that the callbacks must be labelled conservatively early + * on, as getting exact information would degrade both performance and + * scalability. When more accurate grace-period information becomes + * available, previously posted callbacks can be "accelerated", marking + * them to complete at the end of the earlier grace period. + * + * This function operates on an rcu_segcblist structure, and also the + * grace-period sequence number seq at which new callbacks would become + * ready to invoke. Returns true if there are callbacks that won't be + * ready to invoke until seq, false otherwise. + */ +bool rcu_segcblist_accelerate(struct rcu_segcblist *rsclp, unsigned long seq) +{ + int i; + + WARN_ON_ONCE(!rcu_segcblist_is_enabled(rsclp)); + if (rcu_segcblist_restempty(rsclp, RCU_DONE_TAIL)) + return false; + + /* + * Find the segment preceding the oldest segment of callbacks + * whose ->gp_seq[] completion is at or after that passed in via + * "seq", skipping any empty segments. This oldest segment, along + * with any later segments, can be merged in with any newly arrived + * callbacks in the RCU_NEXT_TAIL segment, and assigned "seq" + * as their ->gp_seq[] grace-period completion sequence number. + */ + for (i = RCU_NEXT_READY_TAIL; i > RCU_DONE_TAIL; i--) + if (rsclp->tails[i] != rsclp->tails[i - 1] && + ULONG_CMP_LT(rsclp->gp_seq[i], seq)) + break; + + /* + * If all the segments contain callbacks that correspond to + * earlier grace-period sequence numbers than "seq", leave. + * Assuming that the rcu_segcblist structure has enough + * segments in its arrays, this can only happen if some of + * the non-done segments contain callbacks that really are + * ready to invoke. This situation will get straightened + * out by the next call to rcu_segcblist_advance(). + * + * Also advance to the oldest segment of callbacks whose + * ->gp_seq[] completion is at or after that passed in via "seq", + * skipping any empty segments. + */ + if (++i >= RCU_NEXT_TAIL) + return false; + + /* + * Merge all later callbacks, including newly arrived callbacks, + * into the segment located by the for-loop above. Assign "seq" + * as the ->gp_seq[] value in order to correctly handle the case + * where there were no pending callbacks in the rcu_segcblist + * structure other than in the RCU_NEXT_TAIL segment. + */ + for (; i < RCU_NEXT_TAIL; i++) { + rsclp->tails[i] = rsclp->tails[RCU_NEXT_TAIL]; + rsclp->gp_seq[i] = seq; + } + return true; +} + +/* + * Scan the specified rcu_segcblist structure for callbacks that need + * a grace period later than the one specified by "seq". We don't look + * at the RCU_DONE_TAIL or RCU_NEXT_TAIL segments because they don't + * have a grace-period sequence number. + */ +bool rcu_segcblist_future_gp_needed(struct rcu_segcblist *rsclp, + unsigned long seq) +{ + int i; + + for (i = RCU_WAIT_TAIL; i < RCU_NEXT_TAIL; i++) + if (rsclp->tails[i - 1] != rsclp->tails[i] && + ULONG_CMP_LT(seq, rsclp->gp_seq[i])) + return true; + return false; +} diff --git a/kernel/rcu/rcu_segcblist.h b/kernel/rcu/rcu_segcblist.h new file mode 100644 index 0000000..6e36e36 --- /dev/null +++ b/kernel/rcu/rcu_segcblist.h @@ -0,0 +1,164 @@ +/* + * RCU segmented callback lists, internal-to-rcu header file + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, you can access it online at + * http://www.gnu.org/licenses/gpl-2.0.html. + * + * Copyright IBM Corporation, 2017 + * + * Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com> + */ + +#include <linux/rcu_segcblist.h> + +/* + * Account for the fact that a previously dequeued callback turned out + * to be marked as lazy. + */ +static inline void rcu_cblist_dequeued_lazy(struct rcu_cblist *rclp) +{ + rclp->len_lazy--; +} + +/* + * Interim function to return rcu_cblist head pointer. Longer term, the + * rcu_cblist will be used more pervasively, removing the need for this + * function. + */ +static inline struct rcu_head *rcu_cblist_head(struct rcu_cblist *rclp) +{ + return rclp->head; +} + +/* + * Interim function to return rcu_cblist head pointer. Longer term, the + * rcu_cblist will be used more pervasively, removing the need for this + * function. + */ +static inline struct rcu_head **rcu_cblist_tail(struct rcu_cblist *rclp) +{ + WARN_ON_ONCE(!rclp->head); + return rclp->tail; +} + +void rcu_cblist_init(struct rcu_cblist *rclp); +long rcu_cblist_count_cbs(struct rcu_cblist *rclp, long lim); +struct rcu_head *rcu_cblist_dequeue(struct rcu_cblist *rclp); + +/* + * Is the specified rcu_segcblist structure empty? + * + * But careful! The fact that the ->head field is NULL does not + * necessarily imply that there are no callbacks associated with + * this structure. When callbacks are being invoked, they are + * removed as a group. If callback invocation must be preempted, + * the remaining callbacks will be added back to the list. Either + * way, the counts are updated later. + * + * So it is often the case that rcu_segcblist_n_cbs() should be used + * instead. + */ +static inline bool rcu_segcblist_empty(struct rcu_segcblist *rsclp) +{ + return !rsclp->head; +} + +/* Return number of callbacks in segmented callback list. */ +static inline long rcu_segcblist_n_cbs(struct rcu_segcblist *rsclp) +{ + return READ_ONCE(rsclp->len); +} + +/* Return number of lazy callbacks in segmented callback list. */ +static inline long rcu_segcblist_n_lazy_cbs(struct rcu_segcblist *rsclp) +{ + return rsclp->len_lazy; +} + +/* Return number of lazy callbacks in segmented callback list. */ +static inline long rcu_segcblist_n_nonlazy_cbs(struct rcu_segcblist *rsclp) +{ + return rsclp->len - rsclp->len_lazy; +} + +/* + * Is the specified rcu_segcblist enabled, for example, not corresponding + * to an offline or callback-offloaded CPU? + */ +static inline bool rcu_segcblist_is_enabled(struct rcu_segcblist *rsclp) +{ + return !!rsclp->tails[RCU_NEXT_TAIL]; +} + +/* + * Are all segments following the specified segment of the specified + * rcu_segcblist structure empty of callbacks? (The specified + * segment might well contain callbacks.) + */ +static inline bool rcu_segcblist_restempty(struct rcu_segcblist *rsclp, int seg) +{ + return !*rsclp->tails[seg]; +} + +/* + * Interim function to return rcu_segcblist head pointer. Longer term, the + * rcu_segcblist will be used more pervasively, removing the need for this + * function. + */ +static inline struct rcu_head *rcu_segcblist_head(struct rcu_segcblist *rsclp) +{ + return rsclp->head; +} + +/* + * Interim function to return rcu_segcblist head pointer. Longer term, the + * rcu_segcblist will be used more pervasively, removing the need for this + * function. + */ +static inline struct rcu_head **rcu_segcblist_tail(struct rcu_segcblist *rsclp) +{ + WARN_ON_ONCE(rcu_segcblist_empty(rsclp)); + return rsclp->tails[RCU_NEXT_TAIL]; +} + +void rcu_segcblist_init(struct rcu_segcblist *rsclp); +void rcu_segcblist_disable(struct rcu_segcblist *rsclp); +bool rcu_segcblist_segempty(struct rcu_segcblist *rsclp, int seg); +bool rcu_segcblist_ready_cbs(struct rcu_segcblist *rsclp); +bool rcu_segcblist_pend_cbs(struct rcu_segcblist *rsclp); +struct rcu_head *rcu_segcblist_dequeue(struct rcu_segcblist *rsclp); +void rcu_segcblist_dequeued_lazy(struct rcu_segcblist *rsclp); +struct rcu_head *rcu_segcblist_first_cb(struct rcu_segcblist *rsclp); +struct rcu_head *rcu_segcblist_first_pend_cb(struct rcu_segcblist *rsclp); +bool rcu_segcblist_new_cbs(struct rcu_segcblist *rsclp); +void rcu_segcblist_enqueue(struct rcu_segcblist *rsclp, + struct rcu_head *rhp, bool lazy); +bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp, + struct rcu_head *rhp, bool lazy); +void rcu_segcblist_extract_count(struct rcu_segcblist *rsclp, + struct rcu_cblist *rclp); +void rcu_segcblist_extract_done_cbs(struct rcu_segcblist *rsclp, + struct rcu_cblist *rclp); +void rcu_segcblist_extract_pend_cbs(struct rcu_segcblist *rsclp, + struct rcu_cblist *rclp); +void rcu_segcblist_insert_count(struct rcu_segcblist *rsclp, + struct rcu_cblist *rclp); +void rcu_segcblist_insert_done_cbs(struct rcu_segcblist *rsclp, + struct rcu_cblist *rclp); +void rcu_segcblist_insert_pend_cbs(struct rcu_segcblist *rsclp, + struct rcu_cblist *rclp); +void rcu_segcblist_advance(struct rcu_segcblist *rsclp, unsigned long seq); +bool rcu_segcblist_accelerate(struct rcu_segcblist *rsclp, unsigned long seq); +bool rcu_segcblist_future_gp_needed(struct rcu_segcblist *rsclp, + unsigned long seq); diff --git a/kernel/rcu/srcutiny.c b/kernel/rcu/srcutiny.c index b829352..36e1f82 100644 --- a/kernel/rcu/srcutiny.c +++ b/kernel/rcu/srcutiny.c @@ -30,6 +30,7 @@ #include <linux/srcu.h> #include <linux/rcu_node_tree.h> +#include "rcu_segcblist.h" #include "rcu.h" static int init_srcu_struct_fields(struct srcu_struct *sp) diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 87b070d..3ae8474 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -38,6 +38,7 @@ #include <linux/srcu.h> #include "rcu.h" +#include "rcu_segcblist.h" ulong exp_holdoff = 25 * 1000; /* Holdoff (ns) for auto-expediting. */ module_param(exp_holdoff, ulong, 0444); diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 91fff49..1205c8a 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 (rsp->orphan_done.len_lazy != rsp->orphan_done.len) rcu_idle_count_callbacks_posted(); rcu_segcblist_insert_count(&rdp->cblist, &rsp->orphan_done); @@ -2647,9 +2646,9 @@ 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)); } @@ -2792,17 +2791,16 @@ 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); - trace_rcu_batch_end(rsp->name, count, !rcu_cblist_empty(&rcl), - need_resched(), is_idle_task(current), - rcu_is_callbacks_kthread()); + count = -rcl.len; + 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.h b/kernel/rcu/tree.h index 0e598ab..ba38262 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -30,9 +30,10 @@ #include <linux/seqlock.h> #include <linux/swait.h> #include <linux/stop_machine.h> -#include <linux/rcu_segcblist.h> #include <linux/rcu_node_tree.h> +#include "rcu_segcblist.h" + /* * Dynticks per-CPU state. */ diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 7f1d677..c9a4865 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -1934,20 +1934,20 @@ 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 qll = rcu_cblist_n_lazy_cbs(&rsp->orphan_done); + long ql = rsp->orphan_done.len; + 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())) 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); diff --git a/kernel/rcu/tree_trace.c b/kernel/rcu/tree_trace.c index 30c5bf8..6cea17a 100644 --- a/kernel/rcu/tree_trace.c +++ b/kernel/rcu/tree_trace.c @@ -277,8 +277,8 @@ 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), - rcu_cblist_n_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) { seq_puts(m, "\n"); |