195801d700
The Big QEMU Lock (BQL) has many names and they are confusing. The actual QemuMutex variable is called qemu_global_mutex but it's commonly referred to as the BQL in discussions and some code comments. The locking APIs, however, are called qemu_mutex_lock_iothread() and qemu_mutex_unlock_iothread(). The "iothread" name is historic and comes from when the main thread was split into into KVM vcpu threads and the "iothread" (now called the main loop thread). I have contributed to the confusion myself by introducing a separate --object iothread, a separate concept unrelated to the BQL. The "iothread" name is no longer appropriate for the BQL. Rename the locking APIs to: - void bql_lock(void) - void bql_unlock(void) - bool bql_locked(void) There are more APIs with "iothread" in their names. Subsequent patches will rename them. There are also comments and documentation that will be updated in later patches. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Paul Durrant <paul@xen.org> Acked-by: Fabiano Rosas <farosas@suse.de> Acked-by: David Woodhouse <dwmw@amazon.co.uk> Reviewed-by: Cédric Le Goater <clg@kaod.org> Acked-by: Peter Xu <peterx@redhat.com> Acked-by: Eric Farman <farman@linux.ibm.com> Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com> Acked-by: Hyman Huang <yong.huang@smartx.com> Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com> Message-id: 20240102153529.486531-2-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
83 lines
1.8 KiB
C
83 lines
1.8 KiB
C
/*
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* Dummy cpu thread code
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*
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* Copyright IBM, Corp. 2011
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*
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* Authors:
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* Anthony Liguori <aliguori@us.ibm.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 "qemu/rcu.h"
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#include "sysemu/cpus.h"
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#include "qemu/guest-random.h"
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#include "qemu/main-loop.h"
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#include "hw/core/cpu.h"
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static void *dummy_cpu_thread_fn(void *arg)
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{
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CPUState *cpu = arg;
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rcu_register_thread();
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bql_lock();
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qemu_thread_get_self(cpu->thread);
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cpu->thread_id = qemu_get_thread_id();
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cpu->neg.can_do_io = true;
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current_cpu = cpu;
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#ifndef _WIN32
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sigset_t waitset;
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int r;
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sigemptyset(&waitset);
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sigaddset(&waitset, SIG_IPI);
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#endif
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/* signal CPU creation */
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cpu_thread_signal_created(cpu);
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qemu_guest_random_seed_thread_part2(cpu->random_seed);
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do {
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bql_unlock();
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#ifndef _WIN32
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do {
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int sig;
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r = sigwait(&waitset, &sig);
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} while (r == -1 && (errno == EAGAIN || errno == EINTR));
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if (r == -1) {
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perror("sigwait");
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exit(1);
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}
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#else
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qemu_sem_wait(&cpu->sem);
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#endif
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bql_lock();
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qemu_wait_io_event(cpu);
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} while (!cpu->unplug);
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bql_unlock();
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rcu_unregister_thread();
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return NULL;
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}
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void dummy_start_vcpu_thread(CPUState *cpu)
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{
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char thread_name[VCPU_THREAD_NAME_SIZE];
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cpu->thread = g_malloc0(sizeof(QemuThread));
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cpu->halt_cond = g_malloc0(sizeof(QemuCond));
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qemu_cond_init(cpu->halt_cond);
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snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "CPU %d/DUMMY",
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cpu->cpu_index);
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qemu_thread_create(cpu->thread, thread_name, dummy_cpu_thread_fn, cpu,
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QEMU_THREAD_JOINABLE);
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#ifdef _WIN32
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qemu_sem_init(&cpu->sem, 0);
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#endif
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}
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