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-rw-r--r--kernel/rcu/tree.c213
1 files changed, 85 insertions, 128 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 51d4c3acf32d..84fe96641b2e 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -97,9 +97,6 @@ struct rcu_state sname##_state = { \
 	.gp_state = RCU_GP_IDLE, \
 	.gpnum = 0UL - 300UL, \
 	.completed = 0UL - 300UL, \
-	.orphan_lock = __RAW_SPIN_LOCK_UNLOCKED(&sname##_state.orphan_lock), \
-	.orphan_pend = RCU_CBLIST_INITIALIZER(sname##_state.orphan_pend), \
-	.orphan_done = RCU_CBLIST_INITIALIZER(sname##_state.orphan_done), \
 	.barrier_mutex = __MUTEX_INITIALIZER(sname##_state.barrier_mutex), \
 	.name = RCU_STATE_NAME(sname), \
 	.abbr = sabbr, \
@@ -843,13 +840,9 @@ static void rcu_eqs_enter(bool user)
  */
 void rcu_idle_enter(void)
 {
-	unsigned long flags;
-
-	local_irq_save(flags);
+	RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_idle_enter() invoked with irqs enabled!!!");
 	rcu_eqs_enter(false);
-	local_irq_restore(flags);
 }
-EXPORT_SYMBOL_GPL(rcu_idle_enter);
 
 #ifdef CONFIG_NO_HZ_FULL
 /**
@@ -862,7 +855,8 @@ EXPORT_SYMBOL_GPL(rcu_idle_enter);
  */
 void rcu_user_enter(void)
 {
-	rcu_eqs_enter(1);
+	RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_user_enter() invoked with irqs enabled!!!");
+	rcu_eqs_enter(true);
 }
 #endif /* CONFIG_NO_HZ_FULL */
 
@@ -955,8 +949,10 @@ static void rcu_eqs_exit(bool user)
 	if (oldval & DYNTICK_TASK_NEST_MASK) {
 		rdtp->dynticks_nesting += DYNTICK_TASK_NEST_VALUE;
 	} else {
+		__this_cpu_inc(disable_rcu_irq_enter);
 		rdtp->dynticks_nesting = DYNTICK_TASK_EXIT_IDLE;
 		rcu_eqs_exit_common(oldval, user);
+		__this_cpu_dec(disable_rcu_irq_enter);
 	}
 }
 
@@ -979,7 +975,6 @@ void rcu_idle_exit(void)
 	rcu_eqs_exit(false);
 	local_irq_restore(flags);
 }
-EXPORT_SYMBOL_GPL(rcu_idle_exit);
 
 #ifdef CONFIG_NO_HZ_FULL
 /**
@@ -1358,12 +1353,13 @@ static void rcu_check_gp_kthread_starvation(struct rcu_state *rsp)
 	j = jiffies;
 	gpa = READ_ONCE(rsp->gp_activity);
 	if (j - gpa > 2 * HZ) {
-		pr_err("%s kthread starved for %ld jiffies! g%lu c%lu f%#x %s(%d) ->state=%#lx\n",
+		pr_err("%s kthread starved for %ld jiffies! g%lu c%lu f%#x %s(%d) ->state=%#lx ->cpu=%d\n",
 		       rsp->name, j - gpa,
 		       rsp->gpnum, rsp->completed,
 		       rsp->gp_flags,
 		       gp_state_getname(rsp->gp_state), rsp->gp_state,
-		       rsp->gp_kthread ? rsp->gp_kthread->state : ~0);
+		       rsp->gp_kthread ? rsp->gp_kthread->state : ~0,
+		       rsp->gp_kthread ? task_cpu(rsp->gp_kthread) : -1);
 		if (rsp->gp_kthread) {
 			sched_show_task(rsp->gp_kthread);
 			wake_up_process(rsp->gp_kthread);
@@ -2067,8 +2063,8 @@ static bool rcu_gp_init(struct rcu_state *rsp)
 }
 
 /*
- * Helper function for wait_event_interruptible_timeout() wakeup
- * at force-quiescent-state time.
+ * Helper function for swait_event_idle() wakeup at force-quiescent-state
+ * time.
  */
 static bool rcu_gp_fqs_check_wake(struct rcu_state *rsp, int *gfp)
 {
@@ -2206,9 +2202,8 @@ static int __noreturn rcu_gp_kthread(void *arg)
 					       READ_ONCE(rsp->gpnum),
 					       TPS("reqwait"));
 			rsp->gp_state = RCU_GP_WAIT_GPS;
-			swait_event_interruptible(rsp->gp_wq,
-						 READ_ONCE(rsp->gp_flags) &
-						 RCU_GP_FLAG_INIT);
+			swait_event_idle(rsp->gp_wq, READ_ONCE(rsp->gp_flags) &
+						     RCU_GP_FLAG_INIT);
 			rsp->gp_state = RCU_GP_DONE_GPS;
 			/* Locking provides needed memory barrier. */
 			if (rcu_gp_init(rsp))
@@ -2239,7 +2234,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
 					       READ_ONCE(rsp->gpnum),
 					       TPS("fqswait"));
 			rsp->gp_state = RCU_GP_WAIT_FQS;
-			ret = swait_event_interruptible_timeout(rsp->gp_wq,
+			ret = swait_event_idle_timeout(rsp->gp_wq,
 					rcu_gp_fqs_check_wake(rsp, &gf), j);
 			rsp->gp_state = RCU_GP_DOING_FQS;
 			/* Locking provides needed memory barriers. */
@@ -2409,6 +2404,8 @@ rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp,
 			return;
 		}
 		WARN_ON_ONCE(oldmask); /* Any child must be all zeroed! */
+		WARN_ON_ONCE(rnp->level != rcu_num_lvls - 1 &&
+			     rcu_preempt_blocked_readers_cgp(rnp));
 		rnp->qsmask &= ~mask;
 		trace_rcu_quiescent_state_report(rsp->name, rnp->gpnum,
 						 mask, rnp->qsmask, rnp->level,
@@ -2563,85 +2560,6 @@ rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp)
 }
 
 /*
- * Send the specified CPU's RCU callbacks to the orphanage.  The
- * specified CPU must be offline, and the caller must hold the
- * ->orphan_lock.
- */
-static void
-rcu_send_cbs_to_orphanage(int cpu, struct rcu_state *rsp,
-			  struct rcu_node *rnp, struct rcu_data *rdp)
-{
-	lockdep_assert_held(&rsp->orphan_lock);
-
-	/* No-CBs CPUs do not have orphanable callbacks. */
-	if (!IS_ENABLED(CONFIG_HOTPLUG_CPU) || rcu_is_nocb_cpu(rdp->cpu))
-		return;
-
-	/*
-	 * Orphan the callbacks.  First adjust the counts.  This is safe
-	 * because _rcu_barrier() excludes CPU-hotplug operations, so it
-	 * cannot be running now.  Thus no memory barrier is required.
-	 */
-	rdp->n_cbs_orphaned += rcu_segcblist_n_cbs(&rdp->cblist);
-	rcu_segcblist_extract_count(&rdp->cblist, &rsp->orphan_done);
-
-	/*
-	 * Next, move those callbacks still needing a grace period to
-	 * the orphanage, where some other CPU will pick them up.
-	 * Some of the callbacks might have gone partway through a grace
-	 * period, but that is too bad.  They get to start over because we
-	 * cannot assume that grace periods are synchronized across CPUs.
-	 */
-	rcu_segcblist_extract_pend_cbs(&rdp->cblist, &rsp->orphan_pend);
-
-	/*
-	 * Then move the ready-to-invoke callbacks to the orphanage,
-	 * where some other CPU will pick them up.  These will not be
-	 * required to pass though another grace period: They are done.
-	 */
-	rcu_segcblist_extract_done_cbs(&rdp->cblist, &rsp->orphan_done);
-
-	/* Finally, disallow further callbacks on this CPU.  */
-	rcu_segcblist_disable(&rdp->cblist);
-}
-
-/*
- * Adopt the RCU callbacks from the specified rcu_state structure's
- * orphanage.  The caller must hold the ->orphan_lock.
- */
-static void rcu_adopt_orphan_cbs(struct rcu_state *rsp, unsigned long flags)
-{
-	struct rcu_data *rdp = raw_cpu_ptr(rsp->rda);
-
-	lockdep_assert_held(&rsp->orphan_lock);
-
-	/* No-CBs CPUs are handled specially. */
-	if (!IS_ENABLED(CONFIG_HOTPLUG_CPU) ||
-	    rcu_nocb_adopt_orphan_cbs(rsp, rdp, flags))
-		return;
-
-	/* Do the accounting first. */
-	rdp->n_cbs_adopted += rsp->orphan_done.len;
-	if (rsp->orphan_done.len_lazy != rsp->orphan_done.len)
-		rcu_idle_count_callbacks_posted();
-	rcu_segcblist_insert_count(&rdp->cblist, &rsp->orphan_done);
-
-	/*
-	 * We do not need a memory barrier here because the only way we
-	 * can get here if there is an rcu_barrier() in flight is if
-	 * we are the task doing the rcu_barrier().
-	 */
-
-	/* First adopt the ready-to-invoke callbacks, then the done ones. */
-	rcu_segcblist_insert_done_cbs(&rdp->cblist, &rsp->orphan_done);
-	WARN_ON_ONCE(rsp->orphan_done.head);
-	rcu_segcblist_insert_pend_cbs(&rdp->cblist, &rsp->orphan_pend);
-	WARN_ON_ONCE(rsp->orphan_pend.head);
-	WARN_ON_ONCE(rcu_segcblist_empty(&rdp->cblist) !=
-		     !rcu_segcblist_n_cbs(&rdp->cblist));
-}
-
-/*
  * Trace the fact that this CPU is going offline.
  */
 static void rcu_cleanup_dying_cpu(struct rcu_state *rsp)
@@ -2704,14 +2622,12 @@ static void rcu_cleanup_dead_rnp(struct rcu_node *rnp_leaf)
 
 /*
  * The CPU has been completely removed, and some other CPU is reporting
- * this fact from process context.  Do the remainder of the cleanup,
- * including orphaning the outgoing CPU's RCU callbacks, and also
- * adopting them.  There can only be one CPU hotplug operation at a time,
- * so no other CPU can be attempting to update rcu_cpu_kthread_task.
+ * this fact from process context.  Do the remainder of the cleanup.
+ * There can only be one CPU hotplug operation at a time, so no need for
+ * explicit locking.
  */
 static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
 {
-	unsigned long flags;
 	struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
 	struct rcu_node *rnp = rdp->mynode;  /* Outgoing CPU's rdp & rnp. */
 
@@ -2720,18 +2636,6 @@ static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
 
 	/* Adjust any no-longer-needed kthreads. */
 	rcu_boost_kthread_setaffinity(rnp, -1);
-
-	/* Orphan the dead CPU's callbacks, and adopt them if appropriate. */
-	raw_spin_lock_irqsave(&rsp->orphan_lock, flags);
-	rcu_send_cbs_to_orphanage(cpu, rsp, rnp, rdp);
-	rcu_adopt_orphan_cbs(rsp, flags);
-	raw_spin_unlock_irqrestore(&rsp->orphan_lock, flags);
-
-	WARN_ONCE(rcu_segcblist_n_cbs(&rdp->cblist) != 0 ||
-		  !rcu_segcblist_empty(&rdp->cblist),
-		  "rcu_cleanup_dead_cpu: Callbacks on offline CPU %d: qlen=%lu, 1stCB=%p\n",
-		  cpu, rcu_segcblist_n_cbs(&rdp->cblist),
-		  rcu_segcblist_first_cb(&rdp->cblist));
 }
 
 /*
@@ -3569,10 +3473,11 @@ static void rcu_barrier_callback(struct rcu_head *rhp)
 	struct rcu_state *rsp = rdp->rsp;
 
 	if (atomic_dec_and_test(&rsp->barrier_cpu_count)) {
-		_rcu_barrier_trace(rsp, "LastCB", -1, rsp->barrier_sequence);
+		_rcu_barrier_trace(rsp, TPS("LastCB"), -1,
+				   rsp->barrier_sequence);
 		complete(&rsp->barrier_completion);
 	} else {
-		_rcu_barrier_trace(rsp, "CB", -1, rsp->barrier_sequence);
+		_rcu_barrier_trace(rsp, TPS("CB"), -1, rsp->barrier_sequence);
 	}
 }
 
@@ -3584,14 +3489,15 @@ static void rcu_barrier_func(void *type)
 	struct rcu_state *rsp = type;
 	struct rcu_data *rdp = raw_cpu_ptr(rsp->rda);
 
-	_rcu_barrier_trace(rsp, "IRQ", -1, rsp->barrier_sequence);
+	_rcu_barrier_trace(rsp, TPS("IRQ"), -1, rsp->barrier_sequence);
 	rdp->barrier_head.func = rcu_barrier_callback;
 	debug_rcu_head_queue(&rdp->barrier_head);
 	if (rcu_segcblist_entrain(&rdp->cblist, &rdp->barrier_head, 0)) {
 		atomic_inc(&rsp->barrier_cpu_count);
 	} else {
 		debug_rcu_head_unqueue(&rdp->barrier_head);
-		_rcu_barrier_trace(rsp, "IRQNQ", -1, rsp->barrier_sequence);
+		_rcu_barrier_trace(rsp, TPS("IRQNQ"), -1,
+				   rsp->barrier_sequence);
 	}
 }
 
@@ -3605,14 +3511,15 @@ static void _rcu_barrier(struct rcu_state *rsp)
 	struct rcu_data *rdp;
 	unsigned long s = rcu_seq_snap(&rsp->barrier_sequence);
 
-	_rcu_barrier_trace(rsp, "Begin", -1, s);
+	_rcu_barrier_trace(rsp, TPS("Begin"), -1, s);
 
 	/* Take mutex to serialize concurrent rcu_barrier() requests. */
 	mutex_lock(&rsp->barrier_mutex);
 
 	/* Did someone else do our work for us? */
 	if (rcu_seq_done(&rsp->barrier_sequence, s)) {
-		_rcu_barrier_trace(rsp, "EarlyExit", -1, rsp->barrier_sequence);
+		_rcu_barrier_trace(rsp, TPS("EarlyExit"), -1,
+				   rsp->barrier_sequence);
 		smp_mb(); /* caller's subsequent code after above check. */
 		mutex_unlock(&rsp->barrier_mutex);
 		return;
@@ -3620,7 +3527,7 @@ static void _rcu_barrier(struct rcu_state *rsp)
 
 	/* Mark the start of the barrier operation. */
 	rcu_seq_start(&rsp->barrier_sequence);
-	_rcu_barrier_trace(rsp, "Inc1", -1, rsp->barrier_sequence);
+	_rcu_barrier_trace(rsp, TPS("Inc1"), -1, rsp->barrier_sequence);
 
 	/*
 	 * Initialize the count to one rather than to zero in order to
@@ -3643,10 +3550,10 @@ static void _rcu_barrier(struct rcu_state *rsp)
 		rdp = per_cpu_ptr(rsp->rda, cpu);
 		if (rcu_is_nocb_cpu(cpu)) {
 			if (!rcu_nocb_cpu_needs_barrier(rsp, cpu)) {
-				_rcu_barrier_trace(rsp, "OfflineNoCB", cpu,
+				_rcu_barrier_trace(rsp, TPS("OfflineNoCB"), cpu,
 						   rsp->barrier_sequence);
 			} else {
-				_rcu_barrier_trace(rsp, "OnlineNoCB", cpu,
+				_rcu_barrier_trace(rsp, TPS("OnlineNoCB"), cpu,
 						   rsp->barrier_sequence);
 				smp_mb__before_atomic();
 				atomic_inc(&rsp->barrier_cpu_count);
@@ -3654,11 +3561,11 @@ static void _rcu_barrier(struct rcu_state *rsp)
 					   rcu_barrier_callback, rsp, cpu, 0);
 			}
 		} else if (rcu_segcblist_n_cbs(&rdp->cblist)) {
-			_rcu_barrier_trace(rsp, "OnlineQ", cpu,
+			_rcu_barrier_trace(rsp, TPS("OnlineQ"), cpu,
 					   rsp->barrier_sequence);
 			smp_call_function_single(cpu, rcu_barrier_func, rsp, 1);
 		} else {
-			_rcu_barrier_trace(rsp, "OnlineNQ", cpu,
+			_rcu_barrier_trace(rsp, TPS("OnlineNQ"), cpu,
 					   rsp->barrier_sequence);
 		}
 	}
@@ -3675,7 +3582,7 @@ static void _rcu_barrier(struct rcu_state *rsp)
 	wait_for_completion(&rsp->barrier_completion);
 
 	/* Mark the end of the barrier operation. */
-	_rcu_barrier_trace(rsp, "Inc2", -1, rsp->barrier_sequence);
+	_rcu_barrier_trace(rsp, TPS("Inc2"), -1, rsp->barrier_sequence);
 	rcu_seq_end(&rsp->barrier_sequence);
 
 	/* Other rcu_barrier() invocations can now safely proceed. */
@@ -3777,8 +3684,6 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
 	 */
 	rnp = rdp->mynode;
 	raw_spin_lock_rcu_node(rnp);		/* irqs already disabled. */
-	if (!rdp->beenonline)
-		WRITE_ONCE(rsp->ncpus, READ_ONCE(rsp->ncpus) + 1);
 	rdp->beenonline = true;	 /* We have now been online. */
 	rdp->gpnum = rnp->completed; /* Make CPU later note any new GP. */
 	rdp->completed = rnp->completed;
@@ -3882,6 +3787,8 @@ void rcu_cpu_starting(unsigned int cpu)
 {
 	unsigned long flags;
 	unsigned long mask;
+	int nbits;
+	unsigned long oldmask;
 	struct rcu_data *rdp;
 	struct rcu_node *rnp;
 	struct rcu_state *rsp;
@@ -3892,9 +3799,15 @@ void rcu_cpu_starting(unsigned int cpu)
 		mask = rdp->grpmask;
 		raw_spin_lock_irqsave_rcu_node(rnp, flags);
 		rnp->qsmaskinitnext |= mask;
+		oldmask = rnp->expmaskinitnext;
 		rnp->expmaskinitnext |= mask;
+		oldmask ^= rnp->expmaskinitnext;
+		nbits = bitmap_weight(&oldmask, BITS_PER_LONG);
+		/* Allow lockless access for expedited grace periods. */
+		smp_store_release(&rsp->ncpus, rsp->ncpus + nbits); /* ^^^ */
 		raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
 	}
+	smp_mb(); /* Ensure RCU read-side usage follows above initialization. */
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
@@ -3937,6 +3850,50 @@ void rcu_report_dead(unsigned int cpu)
 	for_each_rcu_flavor(rsp)
 		rcu_cleanup_dying_idle_cpu(cpu, rsp);
 }
+
+/* Migrate the dead CPU's callbacks to the current CPU. */
+static void rcu_migrate_callbacks(int cpu, struct rcu_state *rsp)
+{
+	unsigned long flags;
+	struct rcu_data *my_rdp;
+	struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
+	struct rcu_node *rnp_root = rcu_get_root(rdp->rsp);
+
+	if (rcu_is_nocb_cpu(cpu) || rcu_segcblist_empty(&rdp->cblist))
+		return;  /* No callbacks to migrate. */
+
+	local_irq_save(flags);
+	my_rdp = this_cpu_ptr(rsp->rda);
+	if (rcu_nocb_adopt_orphan_cbs(my_rdp, rdp, flags)) {
+		local_irq_restore(flags);
+		return;
+	}
+	raw_spin_lock_rcu_node(rnp_root); /* irqs already disabled. */
+	rcu_advance_cbs(rsp, rnp_root, rdp); /* Leverage recent GPs. */
+	rcu_advance_cbs(rsp, rnp_root, my_rdp); /* Assign GP to pending CBs. */
+	rcu_segcblist_merge(&my_rdp->cblist, &rdp->cblist);
+	WARN_ON_ONCE(rcu_segcblist_empty(&my_rdp->cblist) !=
+		     !rcu_segcblist_n_cbs(&my_rdp->cblist));
+	raw_spin_unlock_irqrestore_rcu_node(rnp_root, flags);
+	WARN_ONCE(rcu_segcblist_n_cbs(&rdp->cblist) != 0 ||
+		  !rcu_segcblist_empty(&rdp->cblist),
+		  "rcu_cleanup_dead_cpu: Callbacks on offline CPU %d: qlen=%lu, 1stCB=%p\n",
+		  cpu, rcu_segcblist_n_cbs(&rdp->cblist),
+		  rcu_segcblist_first_cb(&rdp->cblist));
+}
+
+/*
+ * The outgoing CPU has just passed through the dying-idle state,
+ * and we are being invoked from the CPU that was IPIed to continue the
+ * offline operation.  We need to migrate the outgoing CPU's callbacks.
+ */
+void rcutree_migrate_callbacks(int cpu)
+{
+	struct rcu_state *rsp;
+
+	for_each_rcu_flavor(rsp)
+		rcu_migrate_callbacks(cpu, rsp);
+}
 #endif
 
 /*
generated by cgit-pink 1.4.1 (git 2.36.1) at 2024-09-25 18:28:53 +0000