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authorRajithaY <rajithax.yerrumsetty@intel.com>2017-04-25 03:31:15 -0700
committerRajitha Yerrumchetty <rajithax.yerrumsetty@intel.com>2017-05-22 06:48:08 +0000
commitbb756eebdac6fd24e8919e2c43f7d2c8c4091f59 (patch)
treeca11e03542edf2d8f631efeca5e1626d211107e3 /qemu/util/rcu.c
parenta14b48d18a9ed03ec191cf16b162206998a895ce (diff)
Adding qemu as a submodule of KVMFORNFV
This Patch includes the changes to add qemu as a submodule to kvmfornfv repo and make use of the updated latest qemu for the execution of all testcase Change-Id: I1280af507a857675c7f81d30c95255635667bdd7 Signed-off-by:RajithaY<rajithax.yerrumsetty@intel.com>
Diffstat (limited to 'qemu/util/rcu.c')
-rw-r--r--qemu/util/rcu.c348
1 files changed, 0 insertions, 348 deletions
diff --git a/qemu/util/rcu.c b/qemu/util/rcu.c
deleted file mode 100644
index bceb3e472..000000000
--- a/qemu/util/rcu.c
+++ /dev/null
@@ -1,348 +0,0 @@
-/*
- * urcu-mb.c
- *
- * Userspace RCU library with explicit memory barriers
- *
- * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
- * Copyright 2015 Red Hat, Inc.
- *
- * Ported to QEMU by Paolo Bonzini <pbonzini@redhat.com>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- *
- * IBM's contributions to this file may be relicensed under LGPLv2 or later.
- */
-
-#include "qemu/osdep.h"
-#include "qemu-common.h"
-#include "qemu/rcu.h"
-#include "qemu/atomic.h"
-#include "qemu/thread.h"
-#include "qemu/main-loop.h"
-
-/*
- * Global grace period counter. Bit 0 is always one in rcu_gp_ctr.
- * Bits 1 and above are defined in synchronize_rcu.
- */
-#define RCU_GP_LOCKED (1UL << 0)
-#define RCU_GP_CTR (1UL << 1)
-
-unsigned long rcu_gp_ctr = RCU_GP_LOCKED;
-
-QemuEvent rcu_gp_event;
-static QemuMutex rcu_registry_lock;
-static QemuMutex rcu_sync_lock;
-
-/*
- * Check whether a quiescent state was crossed between the beginning of
- * update_counter_and_wait and now.
- */
-static inline int rcu_gp_ongoing(unsigned long *ctr)
-{
- unsigned long v;
-
- v = atomic_read(ctr);
- return v && (v != rcu_gp_ctr);
-}
-
-/* Written to only by each individual reader. Read by both the reader and the
- * writers.
- */
-__thread struct rcu_reader_data rcu_reader;
-
-/* Protected by rcu_registry_lock. */
-typedef QLIST_HEAD(, rcu_reader_data) ThreadList;
-static ThreadList registry = QLIST_HEAD_INITIALIZER(registry);
-
-/* Wait for previous parity/grace period to be empty of readers. */
-static void wait_for_readers(void)
-{
- ThreadList qsreaders = QLIST_HEAD_INITIALIZER(qsreaders);
- struct rcu_reader_data *index, *tmp;
-
- for (;;) {
- /* We want to be notified of changes made to rcu_gp_ongoing
- * while we walk the list.
- */
- qemu_event_reset(&rcu_gp_event);
-
- /* Instead of using atomic_mb_set for index->waiting, and
- * atomic_mb_read for index->ctr, memory barriers are placed
- * manually since writes to different threads are independent.
- * atomic_mb_set has a smp_wmb before...
- */
- smp_wmb();
- QLIST_FOREACH(index, &registry, node) {
- atomic_set(&index->waiting, true);
- }
-
- /* ... and a smp_mb after. */
- smp_mb();
-
- QLIST_FOREACH_SAFE(index, &registry, node, tmp) {
- if (!rcu_gp_ongoing(&index->ctr)) {
- QLIST_REMOVE(index, node);
- QLIST_INSERT_HEAD(&qsreaders, index, node);
-
- /* No need for mb_set here, worst of all we
- * get some extra futex wakeups.
- */
- atomic_set(&index->waiting, false);
- }
- }
-
- /* atomic_mb_read has smp_rmb after. */
- smp_rmb();
-
- if (QLIST_EMPTY(&registry)) {
- break;
- }
-
- /* Wait for one thread to report a quiescent state and try again.
- * Release rcu_registry_lock, so rcu_(un)register_thread() doesn't
- * wait too much time.
- *
- * rcu_register_thread() may add nodes to &registry; it will not
- * wake up synchronize_rcu, but that is okay because at least another
- * thread must exit its RCU read-side critical section before
- * synchronize_rcu is done. The next iteration of the loop will
- * move the new thread's rcu_reader from &registry to &qsreaders,
- * because rcu_gp_ongoing() will return false.
- *
- * rcu_unregister_thread() may remove nodes from &qsreaders instead
- * of &registry if it runs during qemu_event_wait. That's okay;
- * the node then will not be added back to &registry by QLIST_SWAP
- * below. The invariant is that the node is part of one list when
- * rcu_registry_lock is released.
- */
- qemu_mutex_unlock(&rcu_registry_lock);
- qemu_event_wait(&rcu_gp_event);
- qemu_mutex_lock(&rcu_registry_lock);
- }
-
- /* put back the reader list in the registry */
- QLIST_SWAP(&registry, &qsreaders, node);
-}
-
-void synchronize_rcu(void)
-{
- qemu_mutex_lock(&rcu_sync_lock);
- qemu_mutex_lock(&rcu_registry_lock);
-
- if (!QLIST_EMPTY(&registry)) {
- /* In either case, the atomic_mb_set below blocks stores that free
- * old RCU-protected pointers.
- */
- if (sizeof(rcu_gp_ctr) < 8) {
- /* For architectures with 32-bit longs, a two-subphases algorithm
- * ensures we do not encounter overflow bugs.
- *
- * Switch parity: 0 -> 1, 1 -> 0.
- */
- atomic_mb_set(&rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR);
- wait_for_readers();
- atomic_mb_set(&rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR);
- } else {
- /* Increment current grace period. */
- atomic_mb_set(&rcu_gp_ctr, rcu_gp_ctr + RCU_GP_CTR);
- }
-
- wait_for_readers();
- }
-
- qemu_mutex_unlock(&rcu_registry_lock);
- qemu_mutex_unlock(&rcu_sync_lock);
-}
-
-
-#define RCU_CALL_MIN_SIZE 30
-
-/* Multi-producer, single-consumer queue based on urcu/static/wfqueue.h
- * from liburcu. Note that head is only used by the consumer.
- */
-static struct rcu_head dummy;
-static struct rcu_head *head = &dummy, **tail = &dummy.next;
-static int rcu_call_count;
-static QemuEvent rcu_call_ready_event;
-
-static void enqueue(struct rcu_head *node)
-{
- struct rcu_head **old_tail;
-
- node->next = NULL;
- old_tail = atomic_xchg(&tail, &node->next);
- atomic_mb_set(old_tail, node);
-}
-
-static struct rcu_head *try_dequeue(void)
-{
- struct rcu_head *node, *next;
-
-retry:
- /* Test for an empty list, which we do not expect. Note that for
- * the consumer head and tail are always consistent. The head
- * is consistent because only the consumer reads/writes it.
- * The tail, because it is the first step in the enqueuing.
- * It is only the next pointers that might be inconsistent.
- */
- if (head == &dummy && atomic_mb_read(&tail) == &dummy.next) {
- abort();
- }
-
- /* If the head node has NULL in its next pointer, the value is
- * wrong and we need to wait until its enqueuer finishes the update.
- */
- node = head;
- next = atomic_mb_read(&head->next);
- if (!next) {
- return NULL;
- }
-
- /* Since we are the sole consumer, and we excluded the empty case
- * above, the queue will always have at least two nodes: the
- * dummy node, and the one being removed. So we do not need to update
- * the tail pointer.
- */
- head = next;
-
- /* If we dequeued the dummy node, add it back at the end and retry. */
- if (node == &dummy) {
- enqueue(node);
- goto retry;
- }
-
- return node;
-}
-
-static void *call_rcu_thread(void *opaque)
-{
- struct rcu_head *node;
-
- rcu_register_thread();
-
- for (;;) {
- int tries = 0;
- int n = atomic_read(&rcu_call_count);
-
- /* Heuristically wait for a decent number of callbacks to pile up.
- * Fetch rcu_call_count now, we only must process elements that were
- * added before synchronize_rcu() starts.
- */
- while (n == 0 || (n < RCU_CALL_MIN_SIZE && ++tries <= 5)) {
- g_usleep(10000);
- if (n == 0) {
- qemu_event_reset(&rcu_call_ready_event);
- n = atomic_read(&rcu_call_count);
- if (n == 0) {
- qemu_event_wait(&rcu_call_ready_event);
- }
- }
- n = atomic_read(&rcu_call_count);
- }
-
- atomic_sub(&rcu_call_count, n);
- synchronize_rcu();
- qemu_mutex_lock_iothread();
- while (n > 0) {
- node = try_dequeue();
- while (!node) {
- qemu_mutex_unlock_iothread();
- qemu_event_reset(&rcu_call_ready_event);
- node = try_dequeue();
- if (!node) {
- qemu_event_wait(&rcu_call_ready_event);
- node = try_dequeue();
- }
- qemu_mutex_lock_iothread();
- }
-
- n--;
- node->func(node);
- }
- qemu_mutex_unlock_iothread();
- }
- abort();
-}
-
-void call_rcu1(struct rcu_head *node, void (*func)(struct rcu_head *node))
-{
- node->func = func;
- enqueue(node);
- atomic_inc(&rcu_call_count);
- qemu_event_set(&rcu_call_ready_event);
-}
-
-void rcu_register_thread(void)
-{
- assert(rcu_reader.ctr == 0);
- qemu_mutex_lock(&rcu_registry_lock);
- QLIST_INSERT_HEAD(&registry, &rcu_reader, node);
- qemu_mutex_unlock(&rcu_registry_lock);
-}
-
-void rcu_unregister_thread(void)
-{
- qemu_mutex_lock(&rcu_registry_lock);
- QLIST_REMOVE(&rcu_reader, node);
- qemu_mutex_unlock(&rcu_registry_lock);
-}
-
-static void rcu_init_complete(void)
-{
- QemuThread thread;
-
- qemu_mutex_init(&rcu_registry_lock);
- qemu_mutex_init(&rcu_sync_lock);
- qemu_event_init(&rcu_gp_event, true);
-
- qemu_event_init(&rcu_call_ready_event, false);
-
- /* The caller is assumed to have iothread lock, so the call_rcu thread
- * must have been quiescent even after forking, just recreate it.
- */
- qemu_thread_create(&thread, "call_rcu", call_rcu_thread,
- NULL, QEMU_THREAD_DETACHED);
-
- rcu_register_thread();
-}
-
-#ifdef CONFIG_POSIX
-static void rcu_init_lock(void)
-{
- qemu_mutex_lock(&rcu_sync_lock);
- qemu_mutex_lock(&rcu_registry_lock);
-}
-
-static void rcu_init_unlock(void)
-{
- qemu_mutex_unlock(&rcu_registry_lock);
- qemu_mutex_unlock(&rcu_sync_lock);
-}
-#endif
-
-void rcu_after_fork(void)
-{
- memset(&registry, 0, sizeof(registry));
- rcu_init_complete();
-}
-
-static void __attribute__((__constructor__)) rcu_init(void)
-{
-#ifdef CONFIG_POSIX
- pthread_atfork(rcu_init_lock, rcu_init_unlock, rcu_init_unlock);
-#endif
- rcu_init_complete();
-}