mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-06 18:16:39 +07:00
1da177e4c3
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
471 lines
14 KiB
C
471 lines
14 KiB
C
/*
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* 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, 2001
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*
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* Authors: Dipankar Sarma <dipankar@in.ibm.com>
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* Manfred Spraul <manfred@colorfullife.com>
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*
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* Based on the original work by Paul McKenney <paulmck@us.ibm.com>
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* and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
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* Papers:
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* http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf
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* http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001)
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*
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* For detailed explanation of Read-Copy Update mechanism see -
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* http://lse.sourceforge.net/locking/rcupdate.html
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*
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*/
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/spinlock.h>
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#include <linux/smp.h>
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#include <linux/interrupt.h>
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#include <linux/sched.h>
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#include <asm/atomic.h>
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#include <linux/bitops.h>
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#include <linux/module.h>
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#include <linux/completion.h>
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#include <linux/moduleparam.h>
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#include <linux/percpu.h>
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#include <linux/notifier.h>
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#include <linux/rcupdate.h>
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#include <linux/cpu.h>
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/* Definition for rcupdate control block. */
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struct rcu_ctrlblk rcu_ctrlblk =
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{ .cur = -300, .completed = -300 };
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struct rcu_ctrlblk rcu_bh_ctrlblk =
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{ .cur = -300, .completed = -300 };
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/* Bookkeeping of the progress of the grace period */
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struct rcu_state {
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spinlock_t lock; /* Guard this struct and writes to rcu_ctrlblk */
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cpumask_t cpumask; /* CPUs that need to switch in order */
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/* for current batch to proceed. */
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};
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static struct rcu_state rcu_state ____cacheline_maxaligned_in_smp =
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{.lock = SPIN_LOCK_UNLOCKED, .cpumask = CPU_MASK_NONE };
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static struct rcu_state rcu_bh_state ____cacheline_maxaligned_in_smp =
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{.lock = SPIN_LOCK_UNLOCKED, .cpumask = CPU_MASK_NONE };
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DEFINE_PER_CPU(struct rcu_data, rcu_data) = { 0L };
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DEFINE_PER_CPU(struct rcu_data, rcu_bh_data) = { 0L };
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/* Fake initialization required by compiler */
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static DEFINE_PER_CPU(struct tasklet_struct, rcu_tasklet) = {NULL};
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static int maxbatch = 10;
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/**
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* call_rcu - Queue an RCU callback for invocation after a grace period.
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* @head: structure to be used for queueing the RCU updates.
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* @func: actual update function to be invoked after the grace period
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*
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* The update function will be invoked some time after a full grace
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* period elapses, in other words after all currently executing RCU
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* read-side critical sections have completed. RCU read-side critical
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* sections are delimited by rcu_read_lock() and rcu_read_unlock(),
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* and may be nested.
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*/
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void fastcall call_rcu(struct rcu_head *head,
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void (*func)(struct rcu_head *rcu))
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{
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unsigned long flags;
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struct rcu_data *rdp;
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head->func = func;
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head->next = NULL;
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local_irq_save(flags);
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rdp = &__get_cpu_var(rcu_data);
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*rdp->nxttail = head;
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rdp->nxttail = &head->next;
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local_irq_restore(flags);
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}
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/**
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* call_rcu_bh - Queue an RCU for invocation after a quicker grace period.
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* @head: structure to be used for queueing the RCU updates.
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* @func: actual update function to be invoked after the grace period
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*
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* The update function will be invoked some time after a full grace
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* period elapses, in other words after all currently executing RCU
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* read-side critical sections have completed. call_rcu_bh() assumes
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* that the read-side critical sections end on completion of a softirq
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* handler. This means that read-side critical sections in process
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* context must not be interrupted by softirqs. This interface is to be
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* used when most of the read-side critical sections are in softirq context.
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* RCU read-side critical sections are delimited by rcu_read_lock() and
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* rcu_read_unlock(), * if in interrupt context or rcu_read_lock_bh()
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* and rcu_read_unlock_bh(), if in process context. These may be nested.
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*/
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void fastcall call_rcu_bh(struct rcu_head *head,
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void (*func)(struct rcu_head *rcu))
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{
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unsigned long flags;
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struct rcu_data *rdp;
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head->func = func;
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head->next = NULL;
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local_irq_save(flags);
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rdp = &__get_cpu_var(rcu_bh_data);
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*rdp->nxttail = head;
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rdp->nxttail = &head->next;
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local_irq_restore(flags);
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}
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/*
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* Invoke the completed RCU callbacks. They are expected to be in
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* a per-cpu list.
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*/
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static void rcu_do_batch(struct rcu_data *rdp)
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{
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struct rcu_head *next, *list;
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int count = 0;
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list = rdp->donelist;
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while (list) {
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next = rdp->donelist = list->next;
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list->func(list);
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list = next;
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if (++count >= maxbatch)
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break;
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}
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if (!rdp->donelist)
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rdp->donetail = &rdp->donelist;
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else
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tasklet_schedule(&per_cpu(rcu_tasklet, rdp->cpu));
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}
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/*
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* Grace period handling:
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* The grace period handling consists out of two steps:
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* - A new grace period is started.
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* This is done by rcu_start_batch. The start is not broadcasted to
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* all cpus, they must pick this up by comparing rcp->cur with
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* rdp->quiescbatch. All cpus are recorded in the
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* rcu_state.cpumask bitmap.
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* - All cpus must go through a quiescent state.
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* Since the start of the grace period is not broadcasted, at least two
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* calls to rcu_check_quiescent_state are required:
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* The first call just notices that a new grace period is running. The
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* following calls check if there was a quiescent state since the beginning
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* of the grace period. If so, it updates rcu_state.cpumask. If
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* the bitmap is empty, then the grace period is completed.
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* rcu_check_quiescent_state calls rcu_start_batch(0) to start the next grace
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* period (if necessary).
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*/
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/*
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* Register a new batch of callbacks, and start it up if there is currently no
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* active batch and the batch to be registered has not already occurred.
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* Caller must hold rcu_state.lock.
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*/
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static void rcu_start_batch(struct rcu_ctrlblk *rcp, struct rcu_state *rsp,
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int next_pending)
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{
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if (next_pending)
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rcp->next_pending = 1;
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if (rcp->next_pending &&
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rcp->completed == rcp->cur) {
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/* Can't change, since spin lock held. */
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cpus_andnot(rsp->cpumask, cpu_online_map, nohz_cpu_mask);
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rcp->next_pending = 0;
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/* next_pending == 0 must be visible in __rcu_process_callbacks()
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* before it can see new value of cur.
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*/
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smp_wmb();
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rcp->cur++;
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}
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}
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/*
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* cpu went through a quiescent state since the beginning of the grace period.
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* Clear it from the cpu mask and complete the grace period if it was the last
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* cpu. Start another grace period if someone has further entries pending
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*/
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static void cpu_quiet(int cpu, struct rcu_ctrlblk *rcp, struct rcu_state *rsp)
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{
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cpu_clear(cpu, rsp->cpumask);
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if (cpus_empty(rsp->cpumask)) {
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/* batch completed ! */
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rcp->completed = rcp->cur;
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rcu_start_batch(rcp, rsp, 0);
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}
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}
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/*
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* Check if the cpu has gone through a quiescent state (say context
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* switch). If so and if it already hasn't done so in this RCU
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* quiescent cycle, then indicate that it has done so.
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*/
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static void rcu_check_quiescent_state(struct rcu_ctrlblk *rcp,
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struct rcu_state *rsp, struct rcu_data *rdp)
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{
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if (rdp->quiescbatch != rcp->cur) {
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/* start new grace period: */
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rdp->qs_pending = 1;
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rdp->passed_quiesc = 0;
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rdp->quiescbatch = rcp->cur;
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return;
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}
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/* Grace period already completed for this cpu?
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* qs_pending is checked instead of the actual bitmap to avoid
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* cacheline trashing.
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*/
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if (!rdp->qs_pending)
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return;
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/*
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* Was there a quiescent state since the beginning of the grace
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* period? If no, then exit and wait for the next call.
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*/
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if (!rdp->passed_quiesc)
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return;
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rdp->qs_pending = 0;
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spin_lock(&rsp->lock);
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/*
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* rdp->quiescbatch/rcp->cur and the cpu bitmap can come out of sync
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* during cpu startup. Ignore the quiescent state.
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*/
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if (likely(rdp->quiescbatch == rcp->cur))
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cpu_quiet(rdp->cpu, rcp, rsp);
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spin_unlock(&rsp->lock);
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}
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#ifdef CONFIG_HOTPLUG_CPU
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/* warning! helper for rcu_offline_cpu. do not use elsewhere without reviewing
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* locking requirements, the list it's pulling from has to belong to a cpu
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* which is dead and hence not processing interrupts.
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*/
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static void rcu_move_batch(struct rcu_data *this_rdp, struct rcu_head *list,
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struct rcu_head **tail)
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{
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local_irq_disable();
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*this_rdp->nxttail = list;
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if (list)
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this_rdp->nxttail = tail;
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local_irq_enable();
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}
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static void __rcu_offline_cpu(struct rcu_data *this_rdp,
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struct rcu_ctrlblk *rcp, struct rcu_state *rsp, struct rcu_data *rdp)
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{
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/* if the cpu going offline owns the grace period
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* we can block indefinitely waiting for it, so flush
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* it here
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*/
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spin_lock_bh(&rsp->lock);
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if (rcp->cur != rcp->completed)
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cpu_quiet(rdp->cpu, rcp, rsp);
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spin_unlock_bh(&rsp->lock);
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rcu_move_batch(this_rdp, rdp->curlist, rdp->curtail);
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rcu_move_batch(this_rdp, rdp->nxtlist, rdp->nxttail);
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}
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static void rcu_offline_cpu(int cpu)
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{
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struct rcu_data *this_rdp = &get_cpu_var(rcu_data);
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struct rcu_data *this_bh_rdp = &get_cpu_var(rcu_bh_data);
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__rcu_offline_cpu(this_rdp, &rcu_ctrlblk, &rcu_state,
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&per_cpu(rcu_data, cpu));
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__rcu_offline_cpu(this_bh_rdp, &rcu_bh_ctrlblk, &rcu_bh_state,
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&per_cpu(rcu_bh_data, cpu));
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put_cpu_var(rcu_data);
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put_cpu_var(rcu_bh_data);
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tasklet_kill_immediate(&per_cpu(rcu_tasklet, cpu), cpu);
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}
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#else
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static void rcu_offline_cpu(int cpu)
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{
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}
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#endif
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/*
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* This does the RCU processing work from tasklet context.
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*/
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static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp,
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struct rcu_state *rsp, struct rcu_data *rdp)
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{
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if (rdp->curlist && !rcu_batch_before(rcp->completed, rdp->batch)) {
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*rdp->donetail = rdp->curlist;
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rdp->donetail = rdp->curtail;
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rdp->curlist = NULL;
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rdp->curtail = &rdp->curlist;
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}
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local_irq_disable();
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if (rdp->nxtlist && !rdp->curlist) {
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rdp->curlist = rdp->nxtlist;
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rdp->curtail = rdp->nxttail;
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rdp->nxtlist = NULL;
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rdp->nxttail = &rdp->nxtlist;
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local_irq_enable();
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/*
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* start the next batch of callbacks
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*/
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/* determine batch number */
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rdp->batch = rcp->cur + 1;
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/* see the comment and corresponding wmb() in
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* the rcu_start_batch()
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*/
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smp_rmb();
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if (!rcp->next_pending) {
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/* and start it/schedule start if it's a new batch */
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spin_lock(&rsp->lock);
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rcu_start_batch(rcp, rsp, 1);
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spin_unlock(&rsp->lock);
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}
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} else {
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local_irq_enable();
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}
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rcu_check_quiescent_state(rcp, rsp, rdp);
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if (rdp->donelist)
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rcu_do_batch(rdp);
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}
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static void rcu_process_callbacks(unsigned long unused)
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{
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__rcu_process_callbacks(&rcu_ctrlblk, &rcu_state,
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&__get_cpu_var(rcu_data));
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__rcu_process_callbacks(&rcu_bh_ctrlblk, &rcu_bh_state,
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&__get_cpu_var(rcu_bh_data));
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}
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void rcu_check_callbacks(int cpu, int user)
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{
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if (user ||
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(idle_cpu(cpu) && !in_softirq() &&
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hardirq_count() <= (1 << HARDIRQ_SHIFT))) {
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rcu_qsctr_inc(cpu);
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rcu_bh_qsctr_inc(cpu);
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} else if (!in_softirq())
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rcu_bh_qsctr_inc(cpu);
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tasklet_schedule(&per_cpu(rcu_tasklet, cpu));
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}
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static void rcu_init_percpu_data(int cpu, struct rcu_ctrlblk *rcp,
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struct rcu_data *rdp)
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{
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memset(rdp, 0, sizeof(*rdp));
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rdp->curtail = &rdp->curlist;
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rdp->nxttail = &rdp->nxtlist;
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rdp->donetail = &rdp->donelist;
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rdp->quiescbatch = rcp->completed;
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rdp->qs_pending = 0;
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rdp->cpu = cpu;
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}
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static void __devinit rcu_online_cpu(int cpu)
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{
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struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
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struct rcu_data *bh_rdp = &per_cpu(rcu_bh_data, cpu);
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rcu_init_percpu_data(cpu, &rcu_ctrlblk, rdp);
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rcu_init_percpu_data(cpu, &rcu_bh_ctrlblk, bh_rdp);
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tasklet_init(&per_cpu(rcu_tasklet, cpu), rcu_process_callbacks, 0UL);
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}
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static int __devinit rcu_cpu_notify(struct notifier_block *self,
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unsigned long action, void *hcpu)
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{
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long cpu = (long)hcpu;
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switch (action) {
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case CPU_UP_PREPARE:
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rcu_online_cpu(cpu);
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break;
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case CPU_DEAD:
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rcu_offline_cpu(cpu);
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break;
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default:
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break;
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}
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return NOTIFY_OK;
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}
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static struct notifier_block __devinitdata rcu_nb = {
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.notifier_call = rcu_cpu_notify,
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};
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/*
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* Initializes rcu mechanism. Assumed to be called early.
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* That is before local timer(SMP) or jiffie timer (uniproc) is setup.
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* Note that rcu_qsctr and friends are implicitly
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* initialized due to the choice of ``0'' for RCU_CTR_INVALID.
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*/
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void __init rcu_init(void)
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{
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rcu_cpu_notify(&rcu_nb, CPU_UP_PREPARE,
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(void *)(long)smp_processor_id());
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/* Register notifier for non-boot CPUs */
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register_cpu_notifier(&rcu_nb);
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}
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struct rcu_synchronize {
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struct rcu_head head;
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struct completion completion;
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};
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/* Because of FASTCALL declaration of complete, we use this wrapper */
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static void wakeme_after_rcu(struct rcu_head *head)
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{
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struct rcu_synchronize *rcu;
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rcu = container_of(head, struct rcu_synchronize, head);
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complete(&rcu->completion);
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}
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/**
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* synchronize_kernel - wait until a grace period has elapsed.
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*
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* Control will return to the caller some time after a full grace
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* period has elapsed, in other words after all currently executing RCU
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* read-side critical sections have completed. RCU read-side critical
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* sections are delimited by rcu_read_lock() and rcu_read_unlock(),
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* and may be nested.
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*/
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void synchronize_kernel(void)
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{
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struct rcu_synchronize rcu;
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init_completion(&rcu.completion);
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/* Will wake me after RCU finished */
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call_rcu(&rcu.head, wakeme_after_rcu);
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/* Wait for it */
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wait_for_completion(&rcu.completion);
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}
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module_param(maxbatch, int, 0);
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EXPORT_SYMBOL_GPL(call_rcu);
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EXPORT_SYMBOL_GPL(call_rcu_bh);
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EXPORT_SYMBOL_GPL(synchronize_kernel);
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