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![Michael Tokarev](/assets/img/avatar_default.png)
glib >= 2.31 always enables thread support and g_thread_supported() is #defined to 1, there's no need to call g_thread_init() anymore, and it definitely does not need to report error which never happens. Keep code for old < 2.31 glibc anyway for now, just #ifdef it differently. Signed-off-by: Michael Tokarev <mjt@tls.msk.ru> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Cc: qemu-trivial@nongnu.org
212 lines
5.7 KiB
C
212 lines
5.7 KiB
C
/*
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* GThread coroutine initialization code
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*
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* Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>
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* Copyright (C) 2011 Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.0 of the License, or (at your option) any later version.
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*
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* This library 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 GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*/
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#include <glib.h>
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#include "qemu-common.h"
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#include "block/coroutine_int.h"
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typedef struct {
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Coroutine base;
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GThread *thread;
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bool runnable;
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bool free_on_thread_exit;
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CoroutineAction action;
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} CoroutineGThread;
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static GStaticMutex coroutine_lock = G_STATIC_MUTEX_INIT;
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/* GLib 2.31 and beyond deprecated various parts of the thread API,
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* but the new interfaces are not available in older GLib versions
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* so we have to cope with both.
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*/
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#if GLIB_CHECK_VERSION(2, 31, 0)
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/* Default zero-initialisation is sufficient for 2.31+ GCond */
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static GCond the_coroutine_cond;
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static GCond *coroutine_cond = &the_coroutine_cond;
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static inline void init_coroutine_cond(void)
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{
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}
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/* Awkwardly, the GPrivate API doesn't provide a way to update the
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* GDestroyNotify handler for the coroutine key dynamically. So instead
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* we track whether or not the CoroutineGThread should be freed on
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* thread exit / coroutine key update using the free_on_thread_exit
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* field.
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*/
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static void coroutine_destroy_notify(gpointer data)
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{
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CoroutineGThread *co = data;
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if (co && co->free_on_thread_exit) {
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g_free(co);
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}
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}
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static GPrivate coroutine_key = G_PRIVATE_INIT(coroutine_destroy_notify);
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static inline CoroutineGThread *get_coroutine_key(void)
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{
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return g_private_get(&coroutine_key);
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}
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static inline void set_coroutine_key(CoroutineGThread *co,
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bool free_on_thread_exit)
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{
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/* Unlike g_static_private_set() this does not call the GDestroyNotify
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* if the previous value of the key was NULL. Fortunately we only need
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* the GDestroyNotify in the non-NULL key case.
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*/
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co->free_on_thread_exit = free_on_thread_exit;
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g_private_replace(&coroutine_key, co);
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}
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static inline GThread *create_thread(GThreadFunc func, gpointer data)
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{
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return g_thread_new("coroutine", func, data);
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}
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#else
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/* Handle older GLib versions */
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static GCond *coroutine_cond;
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static inline void init_coroutine_cond(void)
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{
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coroutine_cond = g_cond_new();
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}
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static GStaticPrivate coroutine_key = G_STATIC_PRIVATE_INIT;
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static inline CoroutineGThread *get_coroutine_key(void)
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{
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return g_static_private_get(&coroutine_key);
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}
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static inline void set_coroutine_key(CoroutineGThread *co,
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bool free_on_thread_exit)
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{
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g_static_private_set(&coroutine_key, co,
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free_on_thread_exit ? (GDestroyNotify)g_free : NULL);
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}
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static inline GThread *create_thread(GThreadFunc func, gpointer data)
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{
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return g_thread_create_full(func, data, 0, TRUE, TRUE,
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G_THREAD_PRIORITY_NORMAL, NULL);
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}
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#endif
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static void __attribute__((constructor)) coroutine_init(void)
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{
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#if !GLIB_CHECK_VERSION(2, 31, 0)
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if (!g_thread_supported()) {
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g_thread_init(NULL);
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}
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#endif
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init_coroutine_cond();
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}
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static void coroutine_wait_runnable_locked(CoroutineGThread *co)
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{
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while (!co->runnable) {
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g_cond_wait(coroutine_cond, g_static_mutex_get_mutex(&coroutine_lock));
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}
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}
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static void coroutine_wait_runnable(CoroutineGThread *co)
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{
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g_static_mutex_lock(&coroutine_lock);
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coroutine_wait_runnable_locked(co);
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g_static_mutex_unlock(&coroutine_lock);
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}
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static gpointer coroutine_thread(gpointer opaque)
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{
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CoroutineGThread *co = opaque;
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set_coroutine_key(co, false);
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coroutine_wait_runnable(co);
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co->base.entry(co->base.entry_arg);
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qemu_coroutine_switch(&co->base, co->base.caller, COROUTINE_TERMINATE);
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return NULL;
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}
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Coroutine *qemu_coroutine_new(void)
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{
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CoroutineGThread *co;
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co = g_malloc0(sizeof(*co));
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co->thread = create_thread(coroutine_thread, co);
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if (!co->thread) {
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g_free(co);
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return NULL;
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}
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return &co->base;
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}
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void qemu_coroutine_delete(Coroutine *co_)
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{
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CoroutineGThread *co = DO_UPCAST(CoroutineGThread, base, co_);
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g_thread_join(co->thread);
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g_free(co);
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}
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CoroutineAction qemu_coroutine_switch(Coroutine *from_,
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Coroutine *to_,
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CoroutineAction action)
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{
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CoroutineGThread *from = DO_UPCAST(CoroutineGThread, base, from_);
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CoroutineGThread *to = DO_UPCAST(CoroutineGThread, base, to_);
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g_static_mutex_lock(&coroutine_lock);
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from->runnable = false;
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from->action = action;
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to->runnable = true;
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to->action = action;
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g_cond_broadcast(coroutine_cond);
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if (action != COROUTINE_TERMINATE) {
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coroutine_wait_runnable_locked(from);
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}
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g_static_mutex_unlock(&coroutine_lock);
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return from->action;
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}
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Coroutine *qemu_coroutine_self(void)
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{
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CoroutineGThread *co = get_coroutine_key();
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if (!co) {
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co = g_malloc0(sizeof(*co));
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co->runnable = true;
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set_coroutine_key(co, true);
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}
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return &co->base;
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}
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bool qemu_in_coroutine(void)
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{
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CoroutineGThread *co = get_coroutine_key();
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return co && co->base.caller;
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}
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