It's efficient, but hackish to call yank unregister calls in channel_close(),
especially it'll be hard to debug when qemu crashed with some yank function
leaked.
Remove that hack, but instead explicitly unregister yank functions at the
places where needed, they are:
(on src)
- migrate_fd_cleanup
- postcopy_pause
(on dst)
- migration_incoming_state_destroy
- postcopy_pause_incoming
Some small helpers are introduced to achieve this task. One of them is called
migration_file_get_ioc(), which tries to fetch the ioc out of the qemu file.
It's a bit tricky because qemufile is also used for savevm/loadvm. We need to
check for NULL to bypass those. Please see comment above that helper for more
information.
Signed-off-by: Peter Xu <pet...@redhat.com>
---
migration/migration.c | 5 +++++
migration/qemu-file-channel.c | 3 ---
migration/qemu-file.c | 12 ++++++++++++
migration/qemu-file.h | 2 ++
migration/savevm.c | 7 +++++++
migration/yank_functions.c | 14 ++++++++++++++
migration/yank_functions.h | 1 +
7 files changed, 41 insertions(+), 3 deletions(-)
diff --git a/migration/migration.c b/migration/migration.c
index 4f48cde796..65b8c2eb52 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -59,6 +59,7 @@
#include "multifd.h"
#include "qemu/yank.h"
#include "sysemu/cpus.h"
+#include "yank_functions.h"
#define MAX_THROTTLE (128 << 20) /* Migration transfer speed throttling
*/
@@ -273,6 +274,7 @@ void migration_incoming_state_destroy(void)
}
if (mis->from_src_file) {
+ migration_ioc_unregister_yank_from_file(mis->from_src_file);
qemu_fclose(mis->from_src_file);
mis->from_src_file = NULL;
}
@@ -1811,6 +1813,7 @@ static void migrate_fd_cleanup(MigrationState *s)
* Close the file handle without the lock to make sure the
* critical section won't block for long.
*/
+ migration_ioc_unregister_yank_from_file(tmp);
qemu_fclose(tmp);
}
@@ -3337,6 +3340,8 @@ static MigThrError postcopy_pause(MigrationState *s)
/* Current channel is possibly broken. Release it. */
assert(s->to_dst_file);
+ /* Unregister yank for current channel */
+ migration_ioc_unregister_yank_from_file(s->to_dst_file);
qemu_mutex_lock(&s->qemu_file_lock);
file = s->to_dst_file;
s->to_dst_file = NULL;
diff --git a/migration/qemu-file-channel.c b/migration/qemu-file-channel.c
index 2f8b1fcd46..bb5a5752df 100644
--- a/migration/qemu-file-channel.c
+++ b/migration/qemu-file-channel.c
@@ -107,9 +107,6 @@ static int channel_close(void *opaque, Error **errp)
int ret;
QIOChannel *ioc = QIO_CHANNEL(opaque);
ret = qio_channel_close(ioc, errp);
- if (OBJECT(ioc)->ref == 1) {
- migration_ioc_unregister_yank(ioc);
- }
object_unref(OBJECT(ioc));
return ret;
}
diff --git a/migration/qemu-file.c b/migration/qemu-file.c
index ada58c94dd..b32ff35e73 100644
--- a/migration/qemu-file.c
+++ b/migration/qemu-file.c
@@ -854,3 +854,15 @@ void qemu_file_set_blocking(QEMUFile *f, bool block)
f->ops->set_blocking(f->opaque, block, NULL);
}
}
+
+/*
+ * Return the ioc object if it's a migration channel. Note: it can return NULL
+ * for callers passing in a non-migration qemufile. E.g. see qemu_fopen_bdrv()
+ * and its usage in e.g. load_snapshot(). So we need to check against NULL
+ * before using it. If without the check, migration_incoming_state_destroy()
+ * could fail for load_snapshot().
+ */
+QIOChannel *migration_file_get_ioc(QEMUFile *file)
+{
+ return file->has_ioc ? QIO_CHANNEL(file->opaque) : NULL;
+}
diff --git a/migration/qemu-file.h b/migration/qemu-file.h
index 80d0e79fd1..59f3f78e8b 100644
--- a/migration/qemu-file.h
+++ b/migration/qemu-file.h
@@ -27,6 +27,7 @@
#include <zlib.h>
#include "exec/cpu-common.h"
+#include "io/channel.h"
/* Read a chunk of data from a file at the given position. The pos argument
* can be ignored if the file is only be used for streaming. The number of
@@ -179,5 +180,6 @@ void ram_control_load_hook(QEMUFile *f, uint64_t flags,
void *data);
size_t ram_control_save_page(QEMUFile *f, ram_addr_t block_offset,
ram_addr_t offset, size_t size,
uint64_t *bytes_sent);
+QIOChannel *migration_file_get_ioc(QEMUFile *file);
#endif
diff --git a/migration/savevm.c b/migration/savevm.c
index 96b5e5d639..7b7b64bd13 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -65,6 +65,7 @@
#include "qemu/bitmap.h"
#include "net/announce.h"
#include "qemu/yank.h"
+#include "yank_functions.h"
const unsigned int postcopy_ram_discard_version;
@@ -2568,6 +2569,12 @@ static bool
postcopy_pause_incoming(MigrationIncomingState *mis)
/* Clear the triggered bit to allow one recovery */
mis->postcopy_recover_triggered = false;
+ /*
+ * Unregister yank with either from/to src would work, since ioc behind it
+ * is the same
+ */
+ migration_ioc_unregister_yank_from_file(mis->from_src_file);
+
assert(mis->from_src_file);
qemu_file_shutdown(mis->from_src_file);
qemu_fclose(mis->from_src_file);
diff --git a/migration/yank_functions.c b/migration/yank_functions.c
index 23697173ae..1f35ba3512 100644
--- a/migration/yank_functions.c
+++ b/migration/yank_functions.c
@@ -14,6 +14,7 @@
#include "qemu/yank.h"
#include "io/channel-socket.h"
#include "io/channel-tls.h"
+#include "qemu-file.h"
void migration_yank_iochannel(void *opaque)
{
@@ -46,3 +47,16 @@ void migration_ioc_unregister_yank(QIOChannel *ioc)
QIO_CHANNEL(ioc));
}
}
+
+void migration_ioc_unregister_yank_from_file(QEMUFile *file)
+{
+ QIOChannel *ioc = migration_file_get_ioc(file);
+
+ if (ioc) {
+ /*
+ * For migration qemufiles, we'll always reach here. Though we'll skip
+ * calls from e.g. savevm/loadvm as they don't use yank.
+ */
+ migration_ioc_unregister_yank(ioc);
+ }
+}
diff --git a/migration/yank_functions.h b/migration/yank_functions.h
index 74c7f18c91..a7577955ed 100644
--- a/migration/yank_functions.h
+++ b/migration/yank_functions.h
@@ -17,3 +17,4 @@
void migration_yank_iochannel(void *opaque);
void migration_ioc_register_yank(QIOChannel *ioc);
void migration_ioc_unregister_yank(QIOChannel *ioc);
+void migration_ioc_unregister_yank_from_file(QEMUFile *file);
--
2.31.1
