From: Wei Yang <richardw.yang@linux.intel.com>
To: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: qemu-devel@nongnu.org, Wei Yang <richardw.yang@linux.intel.com>,
quintela@redhat.com
Subject: Re: [PATCH 3/3] migration/postcopy: replace have_listen_thread check with PostcopyState check
Date: Wed, 9 Oct 2019 09:37:33 +0800 [thread overview]
Message-ID: <20191009013733.GF26203@richard> (raw)
In-Reply-To: <20191008191551.GN3441@work-vm>
On Tue, Oct 08, 2019 at 08:15:51PM +0100, Dr. David Alan Gilbert wrote:
>* Wei Yang (richardw.yang@linux.intel.com) 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 <richardw.yang@linux.intel.com>
>> ---
>> 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?
>
I have to say you are right. listen_thread may not started when PostcopyState
is already set to LISTENING.
The ugly fix may be set PostcopyState back to original one. Not sure whether
you would like this.
>Dave
>
>> --
>> 2.17.1
>>
>--
>Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
--
Wei Yang
Help you, Help me
next prev parent reply other threads:[~2019-10-09 1:39 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-06 0:02 [PATCH 0/3] migration/postcopy: replace have_listen_thread check with PostcopyState check Wei Yang
2019-10-06 0:02 ` [PATCH 1/3] migration/postcopy: mis->have_listen_thread check will never be touched Wei Yang
2019-10-08 18:47 ` Dr. David Alan Gilbert
2019-10-06 0:02 ` [PATCH 2/3] migration/postcopy: postpone setting PostcopyState to END Wei Yang
2019-10-08 19:06 ` Dr. David Alan Gilbert
2019-10-06 0:02 ` [PATCH 3/3] migration/postcopy: replace have_listen_thread check with PostcopyState check Wei Yang
2019-10-08 19:15 ` Dr. David Alan Gilbert
2019-10-09 1:37 ` Wei Yang [this message]
2019-10-09 10:17 ` Dr. David Alan Gilbert
2019-10-10 1:21 ` Wei Yang
2019-10-11 13:58 ` [PATCH 0/3] " Dr. David Alan Gilbert
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