include/linux/rcupdate.h

49 // not-yet-completed RCU grace periods.
156  * Note a quasi-voluntary context switch for RCU-tasks's benefit.
226  * rcu_trace_implies_rcu_gp - does an RCU Tasks Trace grace period imply an RCU grace period?
228  * As an accident of implementation, an RCU Tasks Trace grace period also
229  * acts as an RCU grace period.  However, this could change at any time.
238  * cond_resched_tasks_rcu_qs - Report potential quiescent states to RCU
241  * report potential quiescent states to RCU-tasks even if the cond_resched()
260 #error "Unknown RCU implementation specified to kernel configuration"
361  * ("rcu: Reject RCU_LOCKDEP_WARN() false positives") for more detail.
377 			 "Illegal context switch in RCU read-side critical section");  in rcu_preempt_sleep_check()
388 				 "Illegal context switch in RCU-bh read-side critical section"); \
390 				 "Illegal context switch in RCU-sched read-side critical section"); \
404  * multiple pointers markings to match different RCU implementations
422  * unrcu_pointer - mark a pointer as not being RCU protected
428 #define unrcu_pointer(p) __unrcu_pointer(p, __UNIQUE_ID(rcu))
456 #define rcu_dereference_raw(p) __rcu_dereference_raw(p, __UNIQUE_ID(rcu))
459  * RCU_INITIALIZER() - statically initialize an RCU-protected global variable
465  * rcu_assign_pointer() - assign to RCU-protected pointer
469  * Assigns the specified value to the specified RCU-protected
470  * pointer, ensuring that any concurrent RCU readers will see
477  * will be dereferenced by RCU read-side code.
507  * rcu_replace_pointer() - replace an RCU pointer, returning its old value
508  * @rcu_ptr: RCU pointer, whose old value is returned
512  * Perform a replacement, where @rcu_ptr is an RCU-annotated
525  * rcu_access_pointer() - fetch RCU pointer with no dereferencing
528  * Return the value of the specified RCU-protected pointer, but omit the
529  * lockdep checks for being in an RCU read-side critical section.  This is
531  * not dereferenced, for example, when testing an RCU-protected pointer
535  * Within an RCU read-side critical section, there is little reason to
546  * the case in the context of the RCU callback that is freeing up the data,
551 #define rcu_access_pointer(p) __rcu_access_pointer((p), __UNIQUE_ID(rcu), __rcu)
562  * An implicit check for being in an RCU read-side critical section
583  * which pointers are protected by RCU and checks that the pointer is
587 	__rcu_dereference_check((p), __UNIQUE_ID(rcu), \
595  * This is the RCU-bh counterpart to rcu_dereference_check().  However,
596  * please note that starting in v5.0 kernels, vanilla RCU grace periods
603 	__rcu_dereference_check((p), __UNIQUE_ID(rcu), \
611  * This is the RCU-sched counterpart to rcu_dereference_check().
612  * However, please note that starting in v5.0 kernels, vanilla RCU grace
619 	__rcu_dereference_check((p), __UNIQUE_ID(rcu), \
624  * The tracing infrastructure traces RCU (we want that), but unfortunately
625  * some of the RCU checks causes tracing to lock up the system.
631 	__rcu_dereference_check((p), __UNIQUE_ID(rcu), 1, __rcu)
634  * rcu_dereference_protected() - fetch RCU pointer when updates prevented
638  * Return the value of the specified RCU-protected pointer, but omit
650 	__rcu_dereference_protected((p), __UNIQUE_ID(rcu), (c), __rcu)
654  * rcu_dereference() - fetch RCU-protected pointer for dereferencing
662  * rcu_dereference_bh() - fetch an RCU-bh-protected pointer for dereferencing
670  * rcu_dereference_sched() - fetch RCU-sched-protected pointer for dereferencing
678  * rcu_pointer_handoff() - Hand off a pointer from RCU to other mechanism
682  * is handed off from RCU to some other synchronization mechanism, for
700  * rcu_read_lock() - mark the beginning of an RCU read-side critical section
703  * are within RCU read-side critical sections, then the
706  * on one CPU while other CPUs are within RCU read-side critical
707  * sections, invocation of the corresponding RCU callback is deferred
716  * Note, however, that RCU callbacks are permitted to run concurrently
717  * with new RCU read-side critical sections.  One way that this can happen
718  * is via the following sequence of events: (1) CPU 0 enters an RCU
720  * an RCU callback, (3) CPU 0 exits the RCU read-side critical section,
721  * (4) CPU 2 enters a RCU read-side critical section, (5) the RCU
722  * callback is invoked.  This is legal, because the RCU read-side critical
724  * therefore might be referencing something that the corresponding RCU
726  * RCU callback is invoked.
728  * RCU read-side critical sections may be nested.  Any deferred actions
729  * will be deferred until the outermost RCU read-side critical section
733  * following this rule: don't put anything in an rcu_read_lock() RCU
737  * In non-preemptible RCU implementations (pure TREE_RCU and TINY_RCU),
738  * it is illegal to block while in an RCU read-side critical section.
739  * In preemptible RCU implementations (PREEMPT_RCU) in CONFIG_PREEMPTION
740  * kernel builds, RCU read-side critical sections may be preempted,
741  * but explicit blocking is illegal.  Finally, in preemptible RCU
742  * implementations in real-time (with -rt patchset) kernel builds, RCU
749 	__acquire(RCU);  in rcu_read_lock()
757  * way for writers to lock out RCU readers.  This is a feature, not
758  * a bug -- this property is what provides RCU's performance benefits.
761  * used as well.  RCU does not care how the writers keep out of each
766  * rcu_read_unlock() - marks the end of an RCU read-side critical section.
781 	__release(RCU);  in rcu_read_unlock()
787  * rcu_read_lock_bh() - mark the beginning of an RCU-bh critical section
790  * Note that anything else that disables softirqs can also serve as an RCU
810  * rcu_read_unlock_bh() - marks the end of a softirq-only RCU critical section
824  * rcu_read_lock_sched() - mark the beginning of a RCU-sched critical section
855  * rcu_read_unlock_sched() - marks the end of a RCU-classic critical section
876  * RCU_INIT_POINTER() - initialize an RCU protected pointer
880  * Initialize an RCU-protected pointer in special cases where readers
886  *	RCU readers from concurrently accessing this pointer *or*
899  * will look OK in crash dumps, but any concurrent RCU readers might
903  * If you are creating an RCU-protected linked structure that is accessed
904  * by a single external-to-structure RCU-protected pointer, then you may
905  * use RCU_INIT_POINTER() to initialize the internal RCU-protected
920  * RCU_POINTER_INITIALIZER() - statically initialize an RCU protected pointer
924  * GCC-style initialization for an RCU-protected pointer in a structure field.
940  * Many rcu callbacks functions just call kfree() on the base structure.
1044  * in an RCU read-side critical section that includes a read-side fetch
1062 DEFINE_LOCK_GUARD_0(rcu, rcu_read_lock(), rcu_read_unlock())