4486e89c21
Commit00d09fdbba("vl: pause vcpus before stopping iothreads") and commitdce8921b2b("iothread: Stop threads before main() quits") tried to work around the fact that emulation was still active during termination by stopping iothreads. They suffer from race conditions: 1. virtio_scsi_handle_cmd_vq() racing with iothread_stop_all() hits the virtio_scsi_ctx_check() assertion failure because the BDS AioContext has been modified by iothread_stop_all(). 2. Guest vq kick racing with main loop termination leaves a readable ioeventfd that is handled by the next aio_poll() when external clients are enabled again, resulting in unwanted emulation activity. This patch obsoletes those commits by fully disabling emulation activity when vcpus are stopped. Use the new vm_shutdown() function instead of pause_all_vcpus() so that vm change state handlers are invoked too. Virtio devices will now stop their ioeventfds, preventing further emulation activity after vm_stop(). Note that vm_stop(RUN_STATE_SHUTDOWN) cannot be used because it emits a QMP STOP event that may affect existing clients. It is no longer necessary to call replay_disable_events() directly since vm_shutdown() does so already. Drop iothread_stop_all() since it is no longer used. Cc: Fam Zheng <famz@redhat.com> Cc: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Message-id: 20180307144205.20619-5-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
60 lines
1.5 KiB
C
60 lines
1.5 KiB
C
/*
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* Event loop thread
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*
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* Copyright Red Hat Inc., 2013
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*
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* Authors:
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* Stefan Hajnoczi <stefanha@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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#ifndef IOTHREAD_H
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#define IOTHREAD_H
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#include "block/aio.h"
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#include "qemu/thread.h"
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#define TYPE_IOTHREAD "iothread"
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typedef struct {
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Object parent_obj;
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QemuThread thread;
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AioContext *ctx;
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GMainContext *worker_context;
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GMainLoop *main_loop;
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GOnce once;
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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; /* has iothread_stop() been called? */
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bool running; /* should iothread_run() continue? */
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int thread_id;
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/* AioContext poll parameters */
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int64_t poll_max_ns;
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int64_t poll_grow;
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int64_t poll_shrink;
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} IOThread;
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#define IOTHREAD(obj) \
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OBJECT_CHECK(IOThread, obj, TYPE_IOTHREAD)
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char *iothread_get_id(IOThread *iothread);
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IOThread *iothread_by_id(const char *id);
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AioContext *iothread_get_aio_context(IOThread *iothread);
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GMainContext *iothread_get_g_main_context(IOThread *iothread);
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/*
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* Helpers used to allocate iothreads for internal use. These
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* iothreads will not be seen by monitor clients when query using
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* "query-iothreads".
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*/
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IOThread *iothread_create(const char *id, Error **errp);
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void iothread_stop(IOThread *iothread);
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void iothread_destroy(IOThread *iothread);
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#endif /* IOTHREAD_H */
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