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0cb0406172
On older versions of glib (anything prior to glib commit 0f056ebe from May 2019), the implementation of g_source_ref() and g_source_unref() is not threadsafe for a GSource which is not attached to a GMainContext. QEMU's real iothread.c implementation always attaches its iothread->ctx's GSource to a GMainContext created for that iothread, so it is OK, but the simple test framework implementation in tests/iothread.c was not doing this. This was causing intermittent assertion failures in the test-aio-multithread subtest "/aio/multi/mutex/contended" test on the BSD hosts. (It's unclear why only BSD seems to have been affected -- perhaps a combination of the specific glib version being used in the VMs and their happening to run on a host with a lot of CPUs). Borrow the iothread_init_gcontext() from the real iothread.c and add the corresponding cleanup code and the calls to g_main_context_push/pop_thread_default() so we actually use the GMainContext we create. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Reviewed-by: Peter Xu <peterx@redhat.com> Message-id: 20200106144552.7205-1-peter.maydell@linaro.org
128 lines
3.4 KiB
C
128 lines
3.4 KiB
C
/*
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* Event loop thread implementation for unit tests
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*
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* Copyright Red Hat Inc., 2013, 2016
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*
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* Authors:
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* Stefan Hajnoczi <stefanha@redhat.com>
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* Paolo Bonzini <pbonzini@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*
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*/
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#include "qemu/osdep.h"
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#include "qapi/error.h"
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#include "block/aio.h"
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#include "qemu/main-loop.h"
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#include "qemu/rcu.h"
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#include "iothread.h"
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struct IOThread {
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AioContext *ctx;
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GMainContext *worker_context;
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GMainLoop *main_loop;
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QemuThread thread;
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QemuMutex init_done_lock;
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QemuCond init_done_cond; /* is thread initialization done? */
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bool stopping;
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};
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static __thread IOThread *my_iothread;
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AioContext *qemu_get_current_aio_context(void)
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{
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return my_iothread ? my_iothread->ctx : qemu_get_aio_context();
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}
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static void iothread_init_gcontext(IOThread *iothread)
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{
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GSource *source;
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iothread->worker_context = g_main_context_new();
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source = aio_get_g_source(iothread_get_aio_context(iothread));
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g_source_attach(source, iothread->worker_context);
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g_source_unref(source);
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iothread->main_loop = g_main_loop_new(iothread->worker_context, TRUE);
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}
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static void *iothread_run(void *opaque)
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{
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IOThread *iothread = opaque;
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rcu_register_thread();
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my_iothread = iothread;
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qemu_mutex_lock(&iothread->init_done_lock);
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iothread->ctx = aio_context_new(&error_abort);
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/*
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* We must connect the ctx to a GMainContext, because in older versions
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* of glib the g_source_ref()/unref() functions are not threadsafe
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* on sources without a context.
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*/
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iothread_init_gcontext(iothread);
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/*
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* g_main_context_push_thread_default() must be called before anything
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* in this new thread uses glib.
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*/
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g_main_context_push_thread_default(iothread->worker_context);
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qemu_cond_signal(&iothread->init_done_cond);
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qemu_mutex_unlock(&iothread->init_done_lock);
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while (!atomic_read(&iothread->stopping)) {
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aio_poll(iothread->ctx, true);
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}
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g_main_context_pop_thread_default(iothread->worker_context);
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rcu_unregister_thread();
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return NULL;
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}
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static void iothread_stop_bh(void *opaque)
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{
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IOThread *iothread = opaque;
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iothread->stopping = true;
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}
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void iothread_join(IOThread *iothread)
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{
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aio_bh_schedule_oneshot(iothread->ctx, iothread_stop_bh, iothread);
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qemu_thread_join(&iothread->thread);
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g_main_context_unref(iothread->worker_context);
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g_main_loop_unref(iothread->main_loop);
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qemu_cond_destroy(&iothread->init_done_cond);
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qemu_mutex_destroy(&iothread->init_done_lock);
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aio_context_unref(iothread->ctx);
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g_free(iothread);
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}
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IOThread *iothread_new(void)
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{
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IOThread *iothread = g_new0(IOThread, 1);
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qemu_mutex_init(&iothread->init_done_lock);
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qemu_cond_init(&iothread->init_done_cond);
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qemu_thread_create(&iothread->thread, NULL, iothread_run,
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iothread, QEMU_THREAD_JOINABLE);
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/* Wait for initialization to complete */
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qemu_mutex_lock(&iothread->init_done_lock);
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while (iothread->ctx == NULL) {
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qemu_cond_wait(&iothread->init_done_cond,
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&iothread->init_done_lock);
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}
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qemu_mutex_unlock(&iothread->init_done_lock);
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return iothread;
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}
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AioContext *iothread_get_aio_context(IOThread *iothread)
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{
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return iothread->ctx;
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}
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