* zhanghailiang (zhang.zhanghaili...@huawei.com) wrote:
> If the net connection between primary host and secondary host breaks
> while COLO/COLO incoming threads are doing read() or write().
> It will block until connection is timeout, and the failover process
> will be blocked because of it.
>
> So it is necessary to shutdown all the socket fds used by COLO
> to avoid this situation. Besides, we should close the corresponding
> file descriptors after failvoer BH shutdown them,
> Or there will be an error.
Hi,
There are two parts to this patch:
a) Add some semaphores to sequence failover
b) Use shutdown()
At first I wondered if perhaps they should be split; but I see
the reason for the semaphores is mostly to stop the race between
the fd's getting closed and the shutdown() calls; so I think it's
OK.
Do you have any problems with these semaphores during powering off the
guest?
Dave
> Signed-off-by: zhanghailiang <zhang.zhanghaili...@huawei.com>
> Signed-off-by: Li Zhijian <lizhij...@cn.fujitsu.com>
> Reviewed-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
> Cc: Dr. David Alan Gilbert <dgilb...@redhat.com>
> ---
> include/migration/migration.h | 3 +++
> migration/colo.c | 43
> +++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 46 insertions(+)
>
> diff --git a/include/migration/migration.h b/include/migration/migration.h
> index 487ac1e..7cac877 100644
> --- a/include/migration/migration.h
> +++ b/include/migration/migration.h
> @@ -113,6 +113,7 @@ struct MigrationIncomingState {
> QemuThread colo_incoming_thread;
> /* The coroutine we should enter (back) after failover */
> Coroutine *migration_incoming_co;
> + QemuSemaphore colo_incoming_sem;
>
> /* See savevm.c */
> LoadStateEntry_Head loadvm_handlers;
> @@ -182,6 +183,8 @@ struct MigrationState
> QSIMPLEQ_HEAD(src_page_requests, MigrationSrcPageRequest)
> src_page_requests;
> /* The RAMBlock used in the last src_page_request */
> RAMBlock *last_req_rb;
> + /* The semaphore is used to notify COLO thread that failover is finished
> */
> + QemuSemaphore colo_exit_sem;
>
> /* The semaphore is used to notify COLO thread to do checkpoint */
> QemuSemaphore colo_checkpoint_sem;
> diff --git a/migration/colo.c b/migration/colo.c
> index 08b2e46..3222812 100644
> --- a/migration/colo.c
> +++ b/migration/colo.c
> @@ -59,6 +59,18 @@ static void secondary_vm_do_failover(void)
> /* recover runstate to normal migration finish state */
> autostart = true;
> }
> + /*
> + * Make sure COLO incoming thread not block in recv or send,
> + * If mis->from_src_file and mis->to_src_file use the same fd,
> + * The second shutdown() will return -1, we ignore this value,
> + * It is harmless.
> + */
> + if (mis->from_src_file) {
> + qemu_file_shutdown(mis->from_src_file);
> + }
> + if (mis->to_src_file) {
> + qemu_file_shutdown(mis->to_src_file);
> + }
>
> old_state = failover_set_state(FAILOVER_STATUS_ACTIVE,
> FAILOVER_STATUS_COMPLETED);
> @@ -67,6 +79,8 @@ static void secondary_vm_do_failover(void)
> "secondary VM", FailoverStatus_lookup[old_state]);
> return;
> }
> + /* Notify COLO incoming thread that failover work is finished */
> + qemu_sem_post(&mis->colo_incoming_sem);
> /* For Secondary VM, jump to incoming co */
> if (mis->migration_incoming_co) {
> qemu_coroutine_enter(mis->migration_incoming_co);
> @@ -81,6 +95,18 @@ static void primary_vm_do_failover(void)
> migrate_set_state(&s->state, MIGRATION_STATUS_COLO,
> MIGRATION_STATUS_COMPLETED);
>
> + /*
> + * Wake up COLO thread which may blocked in recv() or send(),
> + * The s->rp_state.from_dst_file and s->to_dst_file may use the
> + * same fd, but we still shutdown the fd for twice, it is harmless.
> + */
> + if (s->to_dst_file) {
> + qemu_file_shutdown(s->to_dst_file);
> + }
> + if (s->rp_state.from_dst_file) {
> + qemu_file_shutdown(s->rp_state.from_dst_file);
> + }
> +
> old_state = failover_set_state(FAILOVER_STATUS_ACTIVE,
> FAILOVER_STATUS_COMPLETED);
> if (old_state != FAILOVER_STATUS_ACTIVE) {
> @@ -88,6 +114,8 @@ static void primary_vm_do_failover(void)
> FailoverStatus_lookup[old_state]);
> return;
> }
> + /* Notify COLO thread that failover work is finished */
> + qemu_sem_post(&s->colo_exit_sem);
> }
>
> void colo_do_failover(MigrationState *s)
> @@ -361,6 +389,14 @@ out:
>
> timer_del(s->colo_delay_timer);
>
> + /* Hope this not to be too long to wait here */
> + qemu_sem_wait(&s->colo_exit_sem);
> + qemu_sem_destroy(&s->colo_exit_sem);
> + /*
> + * Must be called after failover BH is completed,
> + * Or the failover BH may shutdown the wrong fd that
> + * re-used by other threads after we release here.
> + */
> if (s->rp_state.from_dst_file) {
> qemu_fclose(s->rp_state.from_dst_file);
> }
> @@ -385,6 +421,7 @@ void migrate_start_colo_process(MigrationState *s)
> s->colo_delay_timer = timer_new_ms(QEMU_CLOCK_HOST,
> colo_checkpoint_notify, s);
>
> + qemu_sem_init(&s->colo_exit_sem, 0);
> migrate_set_state(&s->state, MIGRATION_STATUS_ACTIVE,
> MIGRATION_STATUS_COLO);
> colo_process_checkpoint(s);
> @@ -423,6 +460,8 @@ void *colo_process_incoming_thread(void *opaque)
> uint64_t value;
> Error *local_err = NULL;
>
> + qemu_sem_init(&mis->colo_incoming_sem, 0);
> +
> migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
> MIGRATION_STATUS_COLO);
>
> @@ -533,6 +572,10 @@ out:
> qemu_fclose(fb);
> }
>
> + /* Hope this not to be too long to loop here */
> + qemu_sem_wait(&mis->colo_incoming_sem);
> + qemu_sem_destroy(&mis->colo_incoming_sem);
> + /* Must be called after failover BH is completed */
> if (mis->to_src_file) {
> qemu_fclose(mis->to_src_file);
> }
> --
> 1.8.3.1
>
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
