c26d34a585
Make rcu_dereference() check for being in an RCU read-side critical section, and create rcu_dereference_bh(), rcu_dereference_sched(), and srcu_dereference() to check for the other flavors of RCU. Also create rcu_dereference_raw() to avoid checking, and make rcu_dereference_check() use rcu_dereference_raw(). Acked-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <1266887105-1528-2-git-send-email-paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
145 lines
4 KiB
C
145 lines
4 KiB
C
/*
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* Sleepable Read-Copy Update mechanism for mutual exclusion
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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, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* Copyright (C) IBM Corporation, 2006
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*
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* Author: Paul McKenney <paulmck@us.ibm.com>
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*
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* For detailed explanation of Read-Copy Update mechanism see -
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* Documentation/RCU/ *.txt
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*
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*/
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#ifndef _LINUX_SRCU_H
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#define _LINUX_SRCU_H
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struct srcu_struct_array {
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int c[2];
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};
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struct srcu_struct {
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int completed;
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struct srcu_struct_array *per_cpu_ref;
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struct mutex mutex;
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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struct lockdep_map dep_map;
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#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
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};
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#ifndef CONFIG_PREEMPT
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#define srcu_barrier() barrier()
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#else /* #ifndef CONFIG_PREEMPT */
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#define srcu_barrier()
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#endif /* #else #ifndef CONFIG_PREEMPT */
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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int __init_srcu_struct(struct srcu_struct *sp, const char *name,
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struct lock_class_key *key);
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#define init_srcu_struct(sp) \
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({ \
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static struct lock_class_key __srcu_key; \
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\
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__init_srcu_struct((sp), #sp, &__srcu_key); \
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})
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# define srcu_read_acquire(sp) \
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lock_acquire(&(sp)->dep_map, 0, 0, 2, 1, NULL, _THIS_IP_)
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# define srcu_read_release(sp) \
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lock_release(&(sp)->dep_map, 1, _THIS_IP_)
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#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
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int init_srcu_struct(struct srcu_struct *sp);
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# define srcu_read_acquire(sp) do { } while (0)
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# define srcu_read_release(sp) do { } while (0)
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#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
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void cleanup_srcu_struct(struct srcu_struct *sp);
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int __srcu_read_lock(struct srcu_struct *sp) __acquires(sp);
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void __srcu_read_unlock(struct srcu_struct *sp, int idx) __releases(sp);
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void synchronize_srcu(struct srcu_struct *sp);
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void synchronize_srcu_expedited(struct srcu_struct *sp);
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long srcu_batches_completed(struct srcu_struct *sp);
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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/**
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* srcu_read_lock_held - might we be in SRCU read-side critical section?
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*
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* If CONFIG_PROVE_LOCKING is selected and enabled, returns nonzero iff in
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* an SRCU read-side critical section. In absence of CONFIG_PROVE_LOCKING,
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* this assumes we are in an SRCU read-side critical section unless it can
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* prove otherwise.
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*/
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static inline int srcu_read_lock_held(struct srcu_struct *sp)
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{
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if (debug_locks)
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return lock_is_held(&sp->dep_map);
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return 1;
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}
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#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
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static inline int srcu_read_lock_held(struct srcu_struct *sp)
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{
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return 1;
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}
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#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
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/**
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* srcu_dereference - fetch SRCU-protected pointer with checking
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*
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* Makes rcu_dereference_check() do the dirty work.
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*/
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#define srcu_dereference(p, sp) \
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rcu_dereference_check(p, srcu_read_lock_held(sp))
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/**
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* srcu_read_lock - register a new reader for an SRCU-protected structure.
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* @sp: srcu_struct in which to register the new reader.
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*
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* Enter an SRCU read-side critical section. Note that SRCU read-side
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* critical sections may be nested.
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*/
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static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp)
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{
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int retval = __srcu_read_lock(sp);
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srcu_read_acquire(sp);
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return retval;
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}
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/**
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* srcu_read_unlock - unregister a old reader from an SRCU-protected structure.
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* @sp: srcu_struct in which to unregister the old reader.
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* @idx: return value from corresponding srcu_read_lock().
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*
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* Exit an SRCU read-side critical section.
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*/
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static inline void srcu_read_unlock(struct srcu_struct *sp, int idx)
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__releases(sp)
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{
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srcu_read_release(sp);
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__srcu_read_unlock(sp, idx);
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}
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#endif
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