diff options
author | 2017-04-25 03:31:15 -0700 | |
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committer | 2017-05-22 06:48:08 +0000 | |
commit | bb756eebdac6fd24e8919e2c43f7d2c8c4091f59 (patch) | |
tree | ca11e03542edf2d8f631efeca5e1626d211107e3 /qemu/util/rcu.c | |
parent | a14b48d18a9ed03ec191cf16b162206998a895ce (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.c | 348 |
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, ®istry, node) { - atomic_set(&index->waiting, true); - } - - /* ... and a smp_mb after. */ - smp_mb(); - - QLIST_FOREACH_SAFE(index, ®istry, 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(®istry)) { - 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 ®istry; 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 ®istry to &qsreaders, - * because rcu_gp_ongoing() will return false. - * - * rcu_unregister_thread() may remove nodes from &qsreaders instead - * of ®istry if it runs during qemu_event_wait. That's okay; - * the node then will not be added back to ®istry 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(®istry, &qsreaders, node); -} - -void synchronize_rcu(void) -{ - qemu_mutex_lock(&rcu_sync_lock); - qemu_mutex_lock(&rcu_registry_lock); - - if (!QLIST_EMPTY(®istry)) { - /* 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(®istry, &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(®istry, 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(); -} |