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486 lines
15 KiB
486 lines
15 KiB
/*
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* Read-Copy Update definitions shared among RCU implementations.
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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, 2011
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*
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* Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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*/
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#ifndef __LINUX_RCU_H
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#define __LINUX_RCU_H
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#include <trace/events/rcu.h>
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#ifdef CONFIG_RCU_TRACE
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#define RCU_TRACE(stmt) stmt
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#else /* #ifdef CONFIG_RCU_TRACE */
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#define RCU_TRACE(stmt)
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#endif /* #else #ifdef CONFIG_RCU_TRACE */
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/*
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* Process-level increment to ->dynticks_nesting field. This allows for
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* architectures that use half-interrupts and half-exceptions from
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* process context.
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*
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* DYNTICK_TASK_NEST_MASK defines a field of width DYNTICK_TASK_NEST_WIDTH
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* that counts the number of process-based reasons why RCU cannot
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* consider the corresponding CPU to be idle, and DYNTICK_TASK_NEST_VALUE
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* is the value used to increment or decrement this field.
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*
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* The rest of the bits could in principle be used to count interrupts,
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* but this would mean that a negative-one value in the interrupt
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* field could incorrectly zero out the DYNTICK_TASK_NEST_MASK field.
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* We therefore provide a two-bit guard field defined by DYNTICK_TASK_MASK
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* that is set to DYNTICK_TASK_FLAG upon initial exit from idle.
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* The DYNTICK_TASK_EXIT_IDLE value is thus the combined value used upon
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* initial exit from idle.
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*/
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#define DYNTICK_TASK_NEST_WIDTH 7
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#define DYNTICK_TASK_NEST_VALUE ((LLONG_MAX >> DYNTICK_TASK_NEST_WIDTH) + 1)
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#define DYNTICK_TASK_NEST_MASK (LLONG_MAX - DYNTICK_TASK_NEST_VALUE + 1)
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#define DYNTICK_TASK_FLAG ((DYNTICK_TASK_NEST_VALUE / 8) * 2)
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#define DYNTICK_TASK_MASK ((DYNTICK_TASK_NEST_VALUE / 8) * 3)
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#define DYNTICK_TASK_EXIT_IDLE (DYNTICK_TASK_NEST_VALUE + \
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DYNTICK_TASK_FLAG)
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/*
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* Grace-period counter management.
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*/
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#define RCU_SEQ_CTR_SHIFT 2
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#define RCU_SEQ_STATE_MASK ((1 << RCU_SEQ_CTR_SHIFT) - 1)
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/*
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* Return the counter portion of a sequence number previously returned
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* by rcu_seq_snap() or rcu_seq_current().
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*/
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static inline unsigned long rcu_seq_ctr(unsigned long s)
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{
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return s >> RCU_SEQ_CTR_SHIFT;
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}
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/*
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* Return the state portion of a sequence number previously returned
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* by rcu_seq_snap() or rcu_seq_current().
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*/
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static inline int rcu_seq_state(unsigned long s)
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{
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return s & RCU_SEQ_STATE_MASK;
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}
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/*
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* Set the state portion of the pointed-to sequence number.
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* The caller is responsible for preventing conflicting updates.
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*/
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static inline void rcu_seq_set_state(unsigned long *sp, int newstate)
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{
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WARN_ON_ONCE(newstate & ~RCU_SEQ_STATE_MASK);
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WRITE_ONCE(*sp, (*sp & ~RCU_SEQ_STATE_MASK) + newstate);
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}
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/* Adjust sequence number for start of update-side operation. */
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static inline void rcu_seq_start(unsigned long *sp)
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{
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WRITE_ONCE(*sp, *sp + 1);
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smp_mb(); /* Ensure update-side operation after counter increment. */
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WARN_ON_ONCE(rcu_seq_state(*sp) != 1);
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}
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/* Adjust sequence number for end of update-side operation. */
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static inline void rcu_seq_end(unsigned long *sp)
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{
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smp_mb(); /* Ensure update-side operation before counter increment. */
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WARN_ON_ONCE(!rcu_seq_state(*sp));
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WRITE_ONCE(*sp, (*sp | RCU_SEQ_STATE_MASK) + 1);
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}
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/* Take a snapshot of the update side's sequence number. */
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static inline unsigned long rcu_seq_snap(unsigned long *sp)
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{
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unsigned long s;
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s = (READ_ONCE(*sp) + 2 * RCU_SEQ_STATE_MASK + 1) & ~RCU_SEQ_STATE_MASK;
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smp_mb(); /* Above access must not bleed into critical section. */
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return s;
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}
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/* Return the current value the update side's sequence number, no ordering. */
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static inline unsigned long rcu_seq_current(unsigned long *sp)
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{
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return READ_ONCE(*sp);
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}
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/*
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* Given a snapshot from rcu_seq_snap(), determine whether or not a
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* full update-side operation has occurred.
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*/
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static inline bool rcu_seq_done(unsigned long *sp, unsigned long s)
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{
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return ULONG_CMP_GE(READ_ONCE(*sp), s);
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}
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/*
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* debug_rcu_head_queue()/debug_rcu_head_unqueue() are used internally
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* by call_rcu() and rcu callback execution, and are therefore not part of the
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* RCU API. Leaving in rcupdate.h because they are used by all RCU flavors.
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*/
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#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
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# define STATE_RCU_HEAD_READY 0
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# define STATE_RCU_HEAD_QUEUED 1
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extern struct debug_obj_descr rcuhead_debug_descr;
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static inline int debug_rcu_head_queue(struct rcu_head *head)
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{
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int r1;
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r1 = debug_object_activate(head, &rcuhead_debug_descr);
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debug_object_active_state(head, &rcuhead_debug_descr,
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STATE_RCU_HEAD_READY,
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STATE_RCU_HEAD_QUEUED);
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return r1;
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}
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static inline void debug_rcu_head_unqueue(struct rcu_head *head)
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{
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debug_object_active_state(head, &rcuhead_debug_descr,
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STATE_RCU_HEAD_QUEUED,
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STATE_RCU_HEAD_READY);
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debug_object_deactivate(head, &rcuhead_debug_descr);
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}
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#else /* !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
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static inline int debug_rcu_head_queue(struct rcu_head *head)
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{
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return 0;
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}
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static inline void debug_rcu_head_unqueue(struct rcu_head *head)
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{
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}
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#endif /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
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void kfree(const void *);
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/*
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* Reclaim the specified callback, either by invoking it (non-lazy case)
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* or freeing it directly (lazy case). Return true if lazy, false otherwise.
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*/
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static inline bool __rcu_reclaim(const char *rn, struct rcu_head *head)
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{
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unsigned long offset = (unsigned long)head->func;
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rcu_lock_acquire(&rcu_callback_map);
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if (__is_kfree_rcu_offset(offset)) {
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RCU_TRACE(trace_rcu_invoke_kfree_callback(rn, head, offset);)
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kfree((void *)head - offset);
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rcu_lock_release(&rcu_callback_map);
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return true;
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} else {
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RCU_TRACE(trace_rcu_invoke_callback(rn, head);)
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head->func(head);
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rcu_lock_release(&rcu_callback_map);
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return false;
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}
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}
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#ifdef CONFIG_RCU_STALL_COMMON
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extern int rcu_cpu_stall_suppress;
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int rcu_jiffies_till_stall_check(void);
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#endif /* #ifdef CONFIG_RCU_STALL_COMMON */
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/*
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* Strings used in tracepoints need to be exported via the
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* tracing system such that tools like perf and trace-cmd can
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* translate the string address pointers to actual text.
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*/
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#define TPS(x) tracepoint_string(x)
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/*
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* Dump the ftrace buffer, but only one time per callsite per boot.
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*/
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#define rcu_ftrace_dump(oops_dump_mode) \
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do { \
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static atomic_t ___rfd_beenhere = ATOMIC_INIT(0); \
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\
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if (!atomic_read(&___rfd_beenhere) && \
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!atomic_xchg(&___rfd_beenhere, 1)) \
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ftrace_dump(oops_dump_mode); \
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} while (0)
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void rcu_early_boot_tests(void);
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void rcu_test_sync_prims(void);
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/*
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* This function really isn't for public consumption, but RCU is special in
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* that context switches can allow the state machine to make progress.
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*/
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extern void resched_cpu(int cpu);
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#if defined(SRCU) || !defined(TINY_RCU)
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#include <linux/rcu_node_tree.h>
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extern int rcu_num_lvls;
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extern int num_rcu_lvl[];
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extern int rcu_num_nodes;
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static bool rcu_fanout_exact;
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static int rcu_fanout_leaf;
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/*
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* Compute the per-level fanout, either using the exact fanout specified
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* or balancing the tree, depending on the rcu_fanout_exact boot parameter.
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*/
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static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt)
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{
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int i;
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if (rcu_fanout_exact) {
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levelspread[rcu_num_lvls - 1] = rcu_fanout_leaf;
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for (i = rcu_num_lvls - 2; i >= 0; i--)
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levelspread[i] = RCU_FANOUT;
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} else {
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int ccur;
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int cprv;
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cprv = nr_cpu_ids;
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for (i = rcu_num_lvls - 1; i >= 0; i--) {
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ccur = levelcnt[i];
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levelspread[i] = (cprv + ccur - 1) / ccur;
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cprv = ccur;
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}
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}
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}
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/*
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* Do a full breadth-first scan of the rcu_node structures for the
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* specified rcu_state structure.
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*/
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#define rcu_for_each_node_breadth_first(rsp, rnp) \
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for ((rnp) = &(rsp)->node[0]; \
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(rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)
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/*
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* Do a breadth-first scan of the non-leaf rcu_node structures for the
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* specified rcu_state structure. Note that if there is a singleton
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* rcu_node tree with but one rcu_node structure, this loop is a no-op.
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*/
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#define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \
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for ((rnp) = &(rsp)->node[0]; \
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(rnp) < (rsp)->level[rcu_num_lvls - 1]; (rnp)++)
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/*
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* Scan the leaves of the rcu_node hierarchy for the specified rcu_state
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* structure. Note that if there is a singleton rcu_node tree with but
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* one rcu_node structure, this loop -will- visit the rcu_node structure.
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* It is still a leaf node, even if it is also the root node.
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*/
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#define rcu_for_each_leaf_node(rsp, rnp) \
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for ((rnp) = (rsp)->level[rcu_num_lvls - 1]; \
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(rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)
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/*
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* Iterate over all possible CPUs in a leaf RCU node.
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*/
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#define for_each_leaf_node_possible_cpu(rnp, cpu) \
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for ((cpu) = cpumask_next(rnp->grplo - 1, cpu_possible_mask); \
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cpu <= rnp->grphi; \
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cpu = cpumask_next((cpu), cpu_possible_mask))
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/*
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* Wrappers for the rcu_node::lock acquire and release.
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*
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* Because the rcu_nodes form a tree, the tree traversal locking will observe
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* different lock values, this in turn means that an UNLOCK of one level
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* followed by a LOCK of another level does not imply a full memory barrier;
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* and most importantly transitivity is lost.
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*
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* In order to restore full ordering between tree levels, augment the regular
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* lock acquire functions with smp_mb__after_unlock_lock().
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*
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* As ->lock of struct rcu_node is a __private field, therefore one should use
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* these wrappers rather than directly call raw_spin_{lock,unlock}* on ->lock.
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*/
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#define raw_spin_lock_rcu_node(p) \
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do { \
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raw_spin_lock(&ACCESS_PRIVATE(p, lock)); \
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smp_mb__after_unlock_lock(); \
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} while (0)
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#define raw_spin_unlock_rcu_node(p) raw_spin_unlock(&ACCESS_PRIVATE(p, lock))
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#define raw_spin_lock_irq_rcu_node(p) \
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do { \
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raw_spin_lock_irq(&ACCESS_PRIVATE(p, lock)); \
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smp_mb__after_unlock_lock(); \
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} while (0)
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#define raw_spin_unlock_irq_rcu_node(p) \
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raw_spin_unlock_irq(&ACCESS_PRIVATE(p, lock))
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#define raw_spin_lock_irqsave_rcu_node(p, flags) \
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do { \
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raw_spin_lock_irqsave(&ACCESS_PRIVATE(p, lock), flags); \
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smp_mb__after_unlock_lock(); \
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} while (0)
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#define raw_spin_unlock_irqrestore_rcu_node(p, flags) \
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raw_spin_unlock_irqrestore(&ACCESS_PRIVATE(p, lock), flags) \
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#define raw_spin_trylock_rcu_node(p) \
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({ \
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bool ___locked = raw_spin_trylock(&ACCESS_PRIVATE(p, lock)); \
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\
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if (___locked) \
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smp_mb__after_unlock_lock(); \
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___locked; \
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})
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#endif /* #if defined(SRCU) || !defined(TINY_RCU) */
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#ifdef CONFIG_TINY_RCU
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/* Tiny RCU doesn't expedite, as its purpose in life is instead to be tiny. */
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static inline bool rcu_gp_is_normal(void) { return true; }
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static inline bool rcu_gp_is_expedited(void) { return false; }
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static inline void rcu_expedite_gp(void) { }
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static inline void rcu_unexpedite_gp(void) { }
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#else /* #ifdef CONFIG_TINY_RCU */
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bool rcu_gp_is_normal(void); /* Internal RCU use. */
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bool rcu_gp_is_expedited(void); /* Internal RCU use. */
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void rcu_expedite_gp(void);
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void rcu_unexpedite_gp(void);
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void rcupdate_announce_bootup_oddness(void);
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#endif /* #else #ifdef CONFIG_TINY_RCU */
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#define RCU_SCHEDULER_INACTIVE 0
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#define RCU_SCHEDULER_INIT 1
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#define RCU_SCHEDULER_RUNNING 2
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#ifdef CONFIG_TINY_RCU
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static inline void rcu_request_urgent_qs_task(struct task_struct *t) { }
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#else /* #ifdef CONFIG_TINY_RCU */
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void rcu_request_urgent_qs_task(struct task_struct *t);
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#endif /* #else #ifdef CONFIG_TINY_RCU */
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enum rcutorture_type {
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RCU_FLAVOR,
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RCU_BH_FLAVOR,
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RCU_SCHED_FLAVOR,
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RCU_TASKS_FLAVOR,
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SRCU_FLAVOR,
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INVALID_RCU_FLAVOR
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};
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#if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU)
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void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags,
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unsigned long *gpnum, unsigned long *completed);
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void rcutorture_record_test_transition(void);
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void rcutorture_record_progress(unsigned long vernum);
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void do_trace_rcu_torture_read(const char *rcutorturename,
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struct rcu_head *rhp,
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unsigned long secs,
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unsigned long c_old,
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unsigned long c);
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#else
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static inline void rcutorture_get_gp_data(enum rcutorture_type test_type,
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int *flags,
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unsigned long *gpnum,
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unsigned long *completed)
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{
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*flags = 0;
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*gpnum = 0;
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*completed = 0;
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}
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static inline void rcutorture_record_test_transition(void) { }
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static inline void rcutorture_record_progress(unsigned long vernum) { }
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#ifdef CONFIG_RCU_TRACE
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void do_trace_rcu_torture_read(const char *rcutorturename,
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struct rcu_head *rhp,
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unsigned long secs,
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unsigned long c_old,
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unsigned long c);
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#else
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#define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \
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do { } while (0)
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#endif
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#endif
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#ifdef CONFIG_TINY_SRCU
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static inline void srcutorture_get_gp_data(enum rcutorture_type test_type,
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struct srcu_struct *sp, int *flags,
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unsigned long *gpnum,
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unsigned long *completed)
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{
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if (test_type != SRCU_FLAVOR)
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return;
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*flags = 0;
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*completed = sp->srcu_idx;
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*gpnum = *completed;
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}
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#elif defined(CONFIG_TREE_SRCU)
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void srcutorture_get_gp_data(enum rcutorture_type test_type,
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struct srcu_struct *sp, int *flags,
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unsigned long *gpnum, unsigned long *completed);
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#endif
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#ifdef CONFIG_TINY_RCU
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static inline unsigned long rcu_batches_started(void) { return 0; }
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static inline unsigned long rcu_batches_started_bh(void) { return 0; }
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static inline unsigned long rcu_batches_started_sched(void) { return 0; }
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static inline unsigned long rcu_batches_completed(void) { return 0; }
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static inline unsigned long rcu_batches_completed_bh(void) { return 0; }
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static inline unsigned long rcu_batches_completed_sched(void) { return 0; }
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static inline unsigned long rcu_exp_batches_completed(void) { return 0; }
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static inline unsigned long rcu_exp_batches_completed_sched(void) { return 0; }
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static inline unsigned long
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srcu_batches_completed(struct srcu_struct *sp) { return 0; }
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static inline void rcu_force_quiescent_state(void) { }
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static inline void rcu_bh_force_quiescent_state(void) { }
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static inline void rcu_sched_force_quiescent_state(void) { }
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static inline void show_rcu_gp_kthreads(void) { }
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#else /* #ifdef CONFIG_TINY_RCU */
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extern unsigned long rcutorture_testseq;
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extern unsigned long rcutorture_vernum;
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unsigned long rcu_batches_started(void);
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unsigned long rcu_batches_started_bh(void);
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unsigned long rcu_batches_started_sched(void);
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unsigned long rcu_batches_completed(void);
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unsigned long rcu_batches_completed_bh(void);
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unsigned long rcu_batches_completed_sched(void);
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unsigned long rcu_exp_batches_completed(void);
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unsigned long rcu_exp_batches_completed_sched(void);
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unsigned long srcu_batches_completed(struct srcu_struct *sp);
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void show_rcu_gp_kthreads(void);
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void rcu_force_quiescent_state(void);
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void rcu_bh_force_quiescent_state(void);
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void rcu_sched_force_quiescent_state(void);
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extern struct workqueue_struct *rcu_gp_wq;
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#endif /* #else #ifdef CONFIG_TINY_RCU */
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#ifdef CONFIG_RCU_NOCB_CPU
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bool rcu_is_nocb_cpu(int cpu);
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#else
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static inline bool rcu_is_nocb_cpu(int cpu) { return false; }
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#endif
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#endif /* __LINUX_RCU_H */
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