* Peter Xu (pet...@redhat.com) wrote:
> Postcopy create threads. A common manner is we init a sem and use it to sync
> with the thread. Namely, we have fault_thread_sem and listen_thread_sem and
> they're only used for this.
>
> Make it a shared infrastructure so it's easier to create yet another thread.
>
> Signed-off-by: Peter Xu <pet...@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
> ---
> migration/migration.h | 8 +++++---
> migration/postcopy-ram.c | 23 +++++++++++++++++------
> migration/postcopy-ram.h | 4 ++++
> migration/savevm.c | 12 +++---------
> 4 files changed, 29 insertions(+), 18 deletions(-)
>
> 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 315f784965..d3ec22e6de 100644
> --- a/migration/postcopy-ram.c
> +++ b/migration/postcopy-ram.c
> @@ -77,6 +77,20 @@ 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.
> @@ -901,7 +915,7 @@ 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;
> @@ -1172,11 +1186,8 @@ 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;
> --
> 2.32.0
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
