diff --git a/migration/migration.h b/migration/migration.h index 42c7395094..8445e1d14a 100644 --- a/migration/migration.h +++ b/migration/migration.h @@ -70,7 +70,11 @@ struct MigrationIncomingState { /* A hook to allow cleanup at the end of incoming migration */ void *transport_data; void (*transport_cleanup)(void *data); - + /* + * Used to sync thread creations. Note that we can't create threads in + * parallel with this sem. + */ + QemuSemaphore thread_sync_sem; /* * Free at the start of the main state load, set as the main thread finishes * loading state. @@ -83,13 +87,11 @@ struct MigrationIncomingState { size_t largest_page_size; bool have_fault_thread; QemuThread fault_thread; - QemuSemaphore fault_thread_sem; /* Set this when we want the fault thread to quit */ bool fault_thread_quit; bool have_listen_thread; QemuThread listen_thread; - QemuSemaphore listen_thread_sem; /* For the kernel to send us notifications */ int userfault_fd; diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c index 30c3508f44..d08d396c63 100644 --- a/migration/postcopy-ram.c +++ b/migration/postcopy-ram.c @@ -78,6 +78,20 @@ int postcopy_notify(enum PostcopyNotifyReason reason, Error **errp) &pnd); } +/* + * NOTE: this routine is not thread safe, we can't call it concurrently. But it + * should be good enough for migration's purposes. + */ +void postcopy_thread_create(MigrationIncomingState *mis, + QemuThread *thread, const char *name, + void *(*fn)(void *), int joinable) +{ + qemu_sem_init(&mis->thread_sync_sem, 0); + qemu_thread_create(thread, name, fn, mis, joinable); + qemu_sem_wait(&mis->thread_sync_sem); + qemu_sem_destroy(&mis->thread_sync_sem); +} + /* Postcopy needs to detect accesses to pages that haven't yet been copied * across, and efficiently map new pages in, the techniques for doing this * are target OS specific. @@ -902,7 +916,7 @@ static void *postcopy_ram_fault_thread(void *opaque) trace_postcopy_ram_fault_thread_entry(); rcu_register_thread(); mis->last_rb = NULL; /* last RAMBlock we sent part of */ - qemu_sem_post(&mis->fault_thread_sem); + qemu_sem_post(&mis->thread_sync_sem); struct pollfd *pfd; size_t pfd_len = 2 + mis->postcopy_remote_fds->len; @@ -1173,11 +1187,8 @@ int postcopy_ram_incoming_setup(MigrationIncomingState *mis) return -1; } - qemu_sem_init(&mis->fault_thread_sem, 0); - qemu_thread_create(&mis->fault_thread, "postcopy/fault", - postcopy_ram_fault_thread, mis, QEMU_THREAD_JOINABLE); - qemu_sem_wait(&mis->fault_thread_sem); - qemu_sem_destroy(&mis->fault_thread_sem); + postcopy_thread_create(mis, &mis->fault_thread, "postcopy/fault", + postcopy_ram_fault_thread, QEMU_THREAD_JOINABLE); mis->have_fault_thread = true; /* Mark so that we get notified of accesses to unwritten areas */ diff --git a/migration/postcopy-ram.h b/migration/postcopy-ram.h index 6d2b3cf124..07684c0e1d 100644 --- a/migration/postcopy-ram.h +++ b/migration/postcopy-ram.h @@ -135,6 +135,10 @@ void postcopy_remove_notifier(NotifierWithReturn *n); /* Call the notifier list set by postcopy_add_start_notifier */ int postcopy_notify(enum PostcopyNotifyReason reason, Error **errp); +void postcopy_thread_create(MigrationIncomingState *mis, + QemuThread *thread, const char *name, + void *(*fn)(void *), int joinable); + struct PostCopyFD; /* ufd is a pointer to the struct uffd_msg *TODO: more Portable! */ diff --git a/migration/savevm.c b/migration/savevm.c index 0ccd7e5e3f..967ff80547 100644 --- a/migration/savevm.c +++ b/migration/savevm.c @@ -1863,7 +1863,7 @@ static void *postcopy_ram_listen_thread(void *opaque) migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE, MIGRATION_STATUS_POSTCOPY_ACTIVE); - qemu_sem_post(&mis->listen_thread_sem); + qemu_sem_post(&mis->thread_sync_sem); trace_postcopy_ram_listen_thread_start(); rcu_register_thread(); @@ -1988,14 +1988,8 @@ static int loadvm_postcopy_handle_listen(MigrationIncomingState *mis) } mis->have_listen_thread = true; - /* Start up the listening thread and wait for it to signal ready */ - qemu_sem_init(&mis->listen_thread_sem, 0); - qemu_thread_create(&mis->listen_thread, "postcopy/listen", - postcopy_ram_listen_thread, NULL, - QEMU_THREAD_DETACHED); - qemu_sem_wait(&mis->listen_thread_sem); - qemu_sem_destroy(&mis->listen_thread_sem); - + postcopy_thread_create(mis, &mis->listen_thread, "postcopy/listen", + postcopy_ram_listen_thread, QEMU_THREAD_DETACHED); trace_loadvm_postcopy_handle_listen("return"); return 0;