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94 lines
3.3 KiB
94 lines
3.3 KiB
/* |
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* RCU segmented callback lists |
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* |
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* This seemingly RCU-private file must be available to SRCU users |
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* because the size of the TREE SRCU srcu_struct structure depends |
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* on these definitions. |
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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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#ifndef __INCLUDE_LINUX_RCU_SEGCBLIST_H |
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#define __INCLUDE_LINUX_RCU_SEGCBLIST_H |
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/* Simple unsegmented callback lists. */ |
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struct rcu_cblist { |
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struct rcu_head *head; |
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struct rcu_head **tail; |
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long len; |
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long len_lazy; |
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}; |
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#define RCU_CBLIST_INITIALIZER(n) { .head = NULL, .tail = &n.head } |
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/* Complicated segmented callback lists. ;-) */ |
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/* |
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* Index values for segments in rcu_segcblist structure. |
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* |
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* The segments are as follows: |
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* |
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* [head, *tails[RCU_DONE_TAIL]): |
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* Callbacks whose grace period has elapsed, and thus can be invoked. |
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* [*tails[RCU_DONE_TAIL], *tails[RCU_WAIT_TAIL]): |
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* Callbacks waiting for the current GP from the current CPU's viewpoint. |
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* [*tails[RCU_WAIT_TAIL], *tails[RCU_NEXT_READY_TAIL]): |
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* Callbacks that arrived before the next GP started, again from |
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* the current CPU's viewpoint. These can be handled by the next GP. |
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* [*tails[RCU_NEXT_READY_TAIL], *tails[RCU_NEXT_TAIL]): |
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* Callbacks that might have arrived after the next GP started. |
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* There is some uncertainty as to when a given GP starts and |
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* ends, but a CPU knows the exact times if it is the one starting |
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* or ending the GP. Other CPUs know that the previous GP ends |
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* before the next one starts. |
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* |
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* Note that RCU_WAIT_TAIL cannot be empty unless RCU_NEXT_READY_TAIL is also |
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* empty. |
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* |
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* The ->gp_seq[] array contains the grace-period number at which the |
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* corresponding segment of callbacks will be ready to invoke. A given |
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* element of this array is meaningful only when the corresponding segment |
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* is non-empty, and it is never valid for RCU_DONE_TAIL (whose callbacks |
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* are already ready to invoke) or for RCU_NEXT_TAIL (whose callbacks have |
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* not yet been assigned a grace-period number). |
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*/ |
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#define RCU_DONE_TAIL 0 /* Also RCU_WAIT head. */ |
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#define RCU_WAIT_TAIL 1 /* Also RCU_NEXT_READY head. */ |
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#define RCU_NEXT_READY_TAIL 2 /* Also RCU_NEXT head. */ |
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#define RCU_NEXT_TAIL 3 |
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#define RCU_CBLIST_NSEGS 4 |
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struct rcu_segcblist { |
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struct rcu_head *head; |
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struct rcu_head **tails[RCU_CBLIST_NSEGS]; |
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unsigned long gp_seq[RCU_CBLIST_NSEGS]; |
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long len; |
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long len_lazy; |
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}; |
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#define RCU_SEGCBLIST_INITIALIZER(n) \ |
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{ \ |
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.head = NULL, \ |
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.tails[RCU_DONE_TAIL] = &n.head, \ |
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.tails[RCU_WAIT_TAIL] = &n.head, \ |
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.tails[RCU_NEXT_READY_TAIL] = &n.head, \ |
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.tails[RCU_NEXT_TAIL] = &n.head, \ |
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} |
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#endif /* __INCLUDE_LINUX_RCU_SEGCBLIST_H */
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