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Re: [PATCH 3/3] migration/postcopy: replace have_listen_thread check wit
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [PATCH 3/3] migration/postcopy: replace have_listen_thread check with PostcopyState check |
Date: |
Tue, 8 Oct 2019 20:15:51 +0100 |
User-agent: |
Mutt/1.12.1 (2019-06-15) |
* Wei Yang (address@hidden) wrote:
> After previous cleanup, postcopy thread is running only when
> PostcopyState is LISTENNING or RUNNING. This means it is not necessary
> to spare a variable have_listen_thread to represent the state.
>
> Replace the check on have_listen_thread with PostcopyState and remove
> the variable.
>
> Signed-off-by: Wei Yang <address@hidden>
> ---
> migration/migration.h | 1 -
> migration/ram.c | 2 +-
> migration/ram.h | 1 +
> migration/savevm.c | 4 +---
> 4 files changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/migration/migration.h b/migration/migration.h
> index 4f2fe193dc..a4d639663d 100644
> --- a/migration/migration.h
> +++ b/migration/migration.h
> @@ -63,7 +63,6 @@ struct MigrationIncomingState {
> /* 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;
>
> diff --git a/migration/ram.c b/migration/ram.c
> index 769d3f6454..dfc50d57d5 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -4188,7 +4188,7 @@ static bool postcopy_is_advised(void)
> return ps >= POSTCOPY_INCOMING_ADVISE && ps < POSTCOPY_INCOMING_END;
> }
>
> -static bool postcopy_is_running(void)
> +bool postcopy_is_running(void)
> {
> PostcopyState ps = postcopy_state_get();
> return ps >= POSTCOPY_INCOMING_LISTENING && ps < POSTCOPY_INCOMING_END;
> diff --git a/migration/ram.h b/migration/ram.h
> index bd0eee79b6..44fe4753ad 100644
> --- a/migration/ram.h
> +++ b/migration/ram.h
> @@ -59,6 +59,7 @@ int ram_postcopy_send_discard_bitmap(MigrationState *ms);
> /* For incoming postcopy discard */
> int ram_discard_range(const char *block_name, uint64_t start, size_t length);
> int ram_postcopy_incoming_init(MigrationIncomingState *mis);
> +bool postcopy_is_running(void);
>
> void ram_handle_compressed(void *host, uint8_t ch, uint64_t size);
>
> diff --git a/migration/savevm.c b/migration/savevm.c
> index dcad8897a3..2a0e0b94df 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -1836,7 +1836,6 @@ static void *postcopy_ram_listen_thread(void *opaque)
> qemu_loadvm_state_cleanup();
>
> rcu_unregister_thread();
> - mis->have_listen_thread = false;
> postcopy_state_set(POSTCOPY_INCOMING_END, NULL);
That now needs a big comment saying it must be the last thing in the
thread, because now it's got meaning that it's here.
>
> return NULL;
> @@ -1880,7 +1879,6 @@ static int
> loadvm_postcopy_handle_listen(MigrationIncomingState *mis)
> return -1;
> }
>
> - 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",
> @@ -2518,7 +2516,7 @@ int qemu_loadvm_state(QEMUFile *f)
>
> trace_qemu_loadvm_state_post_main(ret);
>
> - if (mis->have_listen_thread) {
> + if (postcopy_is_running()) {
> /* Listen thread still going, can't clean up yet */
> return ret;
> }
Can you explain to me why this is afe in the case of a failure in
loadvm_postcopy_handle_listen between the start where it sets
the state to LISTENING, and the point where it currently sets
hasve_listen_thread ? Wouldn't this cause qemu_loadvm_state
not to cleanup?
Dave
> --
> 2.17.1
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
Re: [PATCH 0/3] migration/postcopy: replace have_listen_thread check with PostcopyState check, Dr. David Alan Gilbert, 2019/10/11