include/linux/rcupdate.h

50 // not-yet-completed RCU grace periods.
164  * Note a quasi-voluntary context switch for RCU-tasks's benefit.
234  * rcu_trace_implies_rcu_gp - does an RCU Tasks Trace grace period imply an RCU grace period?
236  * As an accident of implementation, an RCU Tasks Trace grace period also
237  * acts as an RCU grace period.  However, this could change at any time.
246  * cond_resched_tasks_rcu_qs - Report potential quiescent states to RCU
249  * report potential quiescent states to RCU-tasks even if the cond_resched()
259  * rcu_softirq_qs_periodic - Report RCU and RCU-Tasks quiescent states
266  * provide both RCU and RCU-Tasks quiescent states. Note that this macro
269  * Because regions of code that have disabled softirq act as RCU read-side
276  * effect because cond_resched() does not provide RCU-Tasks quiescent states.
299 #error "Unknown RCU implementation specified to kernel configuration"
400  * ("rcu: Reject RCU_LOCKDEP_WARN() false positives") for more detail.
416 			 "Illegal context switch in RCU read-side critical section");  in rcu_preempt_sleep_check()
427 				 "Illegal context switch in RCU-bh read-side critical section"); \
429 				 "Illegal context switch in RCU-sched read-side critical section"); \
470  * lockdep_assert_in_rcu_reader - WARN if not within some type of RCU reader
472  * Splats if lockdep is enabled and there is no RCU reader of any
475  * as RCU readers.
503  * multiple pointers markings to match different RCU implementations
521  * unrcu_pointer - mark a pointer as not being RCU protected
527 #define unrcu_pointer(p) __unrcu_pointer(p, __UNIQUE_ID(rcu))
555 #define rcu_dereference_raw(p) __rcu_dereference_raw(p, __UNIQUE_ID(rcu))
558  * RCU_INITIALIZER() - statically initialize an RCU-protected global variable
564  * rcu_assign_pointer() - assign to RCU-protected pointer
568  * Assigns the specified value to the specified RCU-protected
569  * pointer, ensuring that any concurrent RCU readers will see
576  * will be dereferenced by RCU read-side code.
606  * rcu_replace_pointer() - replace an RCU pointer, returning its old value
607  * @rcu_ptr: RCU pointer, whose old value is returned
611  * Perform a replacement, where @rcu_ptr is an RCU-annotated
624  * rcu_access_pointer() - fetch RCU pointer with no dereferencing
627  * Return the value of the specified RCU-protected pointer, but omit the
628  * lockdep checks for being in an RCU read-side critical section.  This is
630  * not dereferenced, for example, when testing an RCU-protected pointer
634  * Within an RCU read-side critical section, there is little reason to
645  * the case in the context of the RCU callback that is freeing up the data,
650 #define rcu_access_pointer(p) __rcu_access_pointer((p), __UNIQUE_ID(rcu), __rcu)
661  * An implicit check for being in an RCU read-side critical section
682  * which pointers are protected by RCU and checks that the pointer is
686 	__rcu_dereference_check((p), __UNIQUE_ID(rcu), \
694  * This is the RCU-bh counterpart to rcu_dereference_check().  However,
695  * please note that starting in v5.0 kernels, vanilla RCU grace periods
702 	__rcu_dereference_check((p), __UNIQUE_ID(rcu), \
710  * This is the RCU-sched counterpart to rcu_dereference_check().
711  * However, please note that starting in v5.0 kernels, vanilla RCU grace
718 	__rcu_dereference_check((p), __UNIQUE_ID(rcu), \
723  * The tracing infrastructure traces RCU (we want that), but unfortunately
724  * some of the RCU checks causes tracing to lock up the system.
730 	__rcu_dereference_check((p), __UNIQUE_ID(rcu), 1, __rcu)
733  * rcu_dereference_protected() - fetch RCU pointer when updates prevented
737  * Return the value of the specified RCU-protected pointer, but omit
749 	__rcu_dereference_protected((p), __UNIQUE_ID(rcu), (c), __rcu)
753  * rcu_dereference() - fetch RCU-protected pointer for dereferencing
761  * rcu_dereference_bh() - fetch an RCU-bh-protected pointer for dereferencing
769  * rcu_dereference_sched() - fetch RCU-sched-protected pointer for dereferencing
777  * rcu_pointer_handoff() - Hand off a pointer from RCU to other mechanism
781  * is handed off from RCU to some other synchronization mechanism, for
799  * rcu_read_lock() - mark the beginning of an RCU read-side critical section
802  * are within RCU read-side critical sections, then the
805  * on one CPU while other CPUs are within RCU read-side critical
806  * sections, invocation of the corresponding RCU callback is deferred
815  * Note, however, that RCU callbacks are permitted to run concurrently
816  * with new RCU read-side critical sections.  One way that this can happen
817  * is via the following sequence of events: (1) CPU 0 enters an RCU
819  * an RCU callback, (3) CPU 0 exits the RCU read-side critical section,
820  * (4) CPU 2 enters a RCU read-side critical section, (5) the RCU
821  * callback is invoked.  This is legal, because the RCU read-side critical
823  * therefore might be referencing something that the corresponding RCU
825  * RCU callback is invoked.
827  * RCU read-side critical sections may be nested.  Any deferred actions
828  * will be deferred until the outermost RCU read-side critical section
832  * following this rule: don't put anything in an rcu_read_lock() RCU
836  * In non-preemptible RCU implementations (pure TREE_RCU and TINY_RCU),
837  * it is illegal to block while in an RCU read-side critical section.
838  * In preemptible RCU implementations (PREEMPT_RCU) in CONFIG_PREEMPTION
839  * kernel builds, RCU read-side critical sections may be preempted,
840  * but explicit blocking is illegal.  Finally, in preemptible RCU
841  * implementations in real-time (with -rt patchset) kernel builds, RCU
848 	__acquire(RCU);  in rcu_read_lock()
856  * way for writers to lock out RCU readers.  This is a feature, not
857  * a bug -- this property is what provides RCU's performance benefits.
860  * used as well.  RCU does not care how the writers keep out of each
865  * rcu_read_unlock() - marks the end of an RCU read-side critical section.
881 	__release(RCU);  in rcu_read_unlock()
886  * rcu_read_lock_bh() - mark the beginning of an RCU-bh critical section
889  * Note that anything else that disables softirqs can also serve as an RCU
909  * rcu_read_unlock_bh() - marks the end of a softirq-only RCU critical section
923  * rcu_read_lock_sched() - mark the beginning of a RCU-sched critical section
954  * rcu_read_unlock_sched() - marks the end of a RCU-classic critical section
975  * RCU_INIT_POINTER() - initialize an RCU protected pointer
979  * Initialize an RCU-protected pointer in special cases where readers
985  *	RCU readers from concurrently accessing this pointer *or*
998  * will look OK in crash dumps, but any concurrent RCU readers might
1002  * If you are creating an RCU-protected linked structure that is accessed
1003  * by a single external-to-structure RCU-protected pointer, then you may
1004  * use RCU_INIT_POINTER() to initialize the internal RCU-protected
1019  * RCU_POINTER_INITIALIZER() - statically initialize an RCU protected pointer
1023  * GCC-style initialization for an RCU-protected pointer in a structure field.
1039  * Many rcu callbacks functions just call kfree() on the base structure.
1143  * in an RCU read-side critical section that includes a read-side fetch
1161 DEFINE_LOCK_GUARD_0(rcu,
1171 		__release(RCU);