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[PULL 13/14] migration: Centralize BH creation and dispatch
From: |
peterx |
Subject: |
[PULL 13/14] migration: Centralize BH creation and dispatch |
Date: |
Mon, 29 Jan 2024 11:04:04 +0800 |
From: Fabiano Rosas <farosas@suse.de>
Now that the migration state reference counting is correct, further
wrap the bottom half dispatch process to avoid future issues.
Move BH creation and scheduling together and wrap the dispatch with an
intermediary function that will ensure we always keep the ref/unref
balanced.
Also move the responsibility of deleting the BH into the wrapper and
remove the now unnecessary pointers.
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Link: 20240119233922.32588-6-farosas@suse.de">https://lore.kernel.org/r/20240119233922.32588-6-farosas@suse.de
Signed-off-by: Peter Xu <peterx@redhat.com>
---
migration/migration.h | 5 +---
migration/migration.c | 65 +++++++++++++++++++++++++------------------
migration/savevm.c | 7 +----
3 files changed, 40 insertions(+), 37 deletions(-)
diff --git a/migration/migration.h b/migration/migration.h
index a589ae8650..f2c8b8f286 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -159,8 +159,6 @@ struct MigrationIncomingState {
/* PostCopyFD's for external userfaultfds & handlers of shared memory */
GArray *postcopy_remote_fds;
- QEMUBH *bh;
-
int state;
/*
@@ -255,8 +253,6 @@ struct MigrationState {
/*< public >*/
QemuThread thread;
- QEMUBH *vm_start_bh;
- QEMUBH *cleanup_bh;
/* Protected by qemu_file_lock */
QEMUFile *to_dst_file;
/* Postcopy specific transfer channel */
@@ -528,6 +524,7 @@ int foreach_not_ignored_block(RAMBlockIterFunc func, void
*opaque);
void migration_make_urgent_request(void);
void migration_consume_urgent_request(void);
bool migration_rate_limit(void);
+void migration_bh_schedule(QEMUBHFunc *cb, void *opaque);
void migration_cancel(const Error *error);
void migration_populate_vfio_info(MigrationInfo *info);
diff --git a/migration/migration.c b/migration/migration.c
index 0e7f101d64..d5f705ceef 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -199,8 +199,39 @@ void migration_object_init(void)
dirty_bitmap_mig_init();
}
-static void migration_bh_schedule(MigrationState *s, QEMUBH *bh)
+typedef struct {
+ QEMUBH *bh;
+ QEMUBHFunc *cb;
+ void *opaque;
+} MigrationBH;
+
+static void migration_bh_dispatch_bh(void *opaque)
{
+ MigrationState *s = migrate_get_current();
+ MigrationBH *migbh = opaque;
+
+ /* cleanup this BH */
+ qemu_bh_delete(migbh->bh);
+ migbh->bh = NULL;
+
+ /* dispatch the other one */
+ migbh->cb(migbh->opaque);
+ object_unref(OBJECT(s));
+
+ g_free(migbh);
+}
+
+void migration_bh_schedule(QEMUBHFunc *cb, void *opaque)
+{
+ MigrationState *s = migrate_get_current();
+ MigrationBH *migbh = g_new0(MigrationBH, 1);
+ QEMUBH *bh = qemu_bh_new(migration_bh_dispatch_bh, migbh);
+
+ /* Store these to dispatch when the BH runs */
+ migbh->bh = bh;
+ migbh->cb = cb;
+ migbh->opaque = opaque;
+
/*
* Ref the state for bh, because it may be called when
* there're already no other refs
@@ -656,9 +687,7 @@ static void process_incoming_migration_bh(void *opaque)
*/
migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
MIGRATION_STATUS_COMPLETED);
- qemu_bh_delete(mis->bh);
migration_incoming_state_destroy();
- object_unref(OBJECT(migrate_get_current()));
}
static void coroutine_fn
@@ -723,8 +752,7 @@ process_incoming_migration_co(void *opaque)
goto fail;
}
- mis->bh = qemu_bh_new(process_incoming_migration_bh, mis);
- migration_bh_schedule(migrate_get_current(), mis->bh);
+ migration_bh_schedule(process_incoming_migration_bh, mis);
return;
fail:
migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
@@ -1285,9 +1313,6 @@ void migrate_set_state(int *state, int old_state, int
new_state)
static void migrate_fd_cleanup(MigrationState *s)
{
- qemu_bh_delete(s->cleanup_bh);
- s->cleanup_bh = NULL;
-
g_free(s->hostname);
s->hostname = NULL;
json_writer_free(s->vmdesc);
@@ -1343,9 +1368,7 @@ static void migrate_fd_cleanup(MigrationState *s)
static void migrate_fd_cleanup_bh(void *opaque)
{
- MigrationState *s = opaque;
- migrate_fd_cleanup(s);
- object_unref(OBJECT(s));
+ migrate_fd_cleanup(opaque);
}
void migrate_set_error(MigrationState *s, const Error *error)
@@ -1568,8 +1591,6 @@ int migrate_init(MigrationState *s, Error **errp)
* parameters/capabilities that the user set, and
* locks.
*/
- s->cleanup_bh = 0;
- s->vm_start_bh = 0;
s->to_dst_file = NULL;
s->state = MIGRATION_STATUS_NONE;
s->rp_state.from_dst_file = NULL;
@@ -3139,7 +3160,8 @@ static void migration_iteration_finish(MigrationState *s)
error_report("%s: Unknown ending state %d", __func__, s->state);
break;
}
- migration_bh_schedule(s, s->cleanup_bh);
+
+ migration_bh_schedule(migrate_fd_cleanup_bh, s);
bql_unlock();
}
@@ -3170,7 +3192,7 @@ static void bg_migration_iteration_finish(MigrationState
*s)
break;
}
- migration_bh_schedule(s, s->cleanup_bh);
+ migration_bh_schedule(migrate_fd_cleanup_bh, s);
bql_unlock();
}
@@ -3376,12 +3398,8 @@ static void bg_migration_vm_start_bh(void *opaque)
{
MigrationState *s = opaque;
- qemu_bh_delete(s->vm_start_bh);
- s->vm_start_bh = NULL;
-
vm_resume(s->vm_old_state);
migration_downtime_end(s);
- object_unref(OBJECT(s));
}
/**
@@ -3485,8 +3503,7 @@ static void *bg_migration_thread(void *opaque)
* calling VM state change notifiers from vm_start() would initiate
* writes to virtio VQs memory which is in write-protected region.
*/
- s->vm_start_bh = qemu_bh_new(bg_migration_vm_start_bh, s);
- migration_bh_schedule(s, s->vm_start_bh);
+ migration_bh_schedule(bg_migration_vm_start_bh, s);
bql_unlock();
while (migration_is_active(s)) {
@@ -3542,12 +3559,6 @@ void migrate_fd_connect(MigrationState *s, Error
*error_in)
migrate_error_free(s);
s->expected_downtime = migrate_downtime_limit();
- if (resume) {
- assert(s->cleanup_bh);
- } else {
- assert(!s->cleanup_bh);
- s->cleanup_bh = qemu_bh_new(migrate_fd_cleanup_bh, s);
- }
if (error_in) {
migrate_fd_error(s, error_in);
if (resume) {
diff --git a/migration/savevm.c b/migration/savevm.c
index 93387350c7..d612c8a902 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2171,10 +2171,7 @@ static void loadvm_postcopy_handle_run_bh(void *opaque)
runstate_set(RUN_STATE_PAUSED);
}
- qemu_bh_delete(mis->bh);
-
trace_vmstate_downtime_checkpoint("dst-postcopy-bh-vm-started");
- object_unref(OBJECT(migration_get_current()));
}
/* After all discards we can start running and asking for pages */
@@ -2189,9 +2186,7 @@ static int
loadvm_postcopy_handle_run(MigrationIncomingState *mis)
}
postcopy_state_set(POSTCOPY_INCOMING_RUNNING);
- mis->bh = qemu_bh_new(loadvm_postcopy_handle_run_bh, mis);
- object_ref(OBJECT(migration_get_current()));
- qemu_bh_schedule(mis->bh);
+ migration_bh_schedule(loadvm_postcopy_handle_run_bh, mis);
/* We need to finish reading the stream from the package
* and also stop reading anything more from the stream that loaded the
--
2.43.0
- [PULL 03/14] migration: Make threshold_size an uint64_t, (continued)
- [PULL 03/14] migration: Make threshold_size an uint64_t, peterx, 2024/01/28
- [PULL 05/14] analyze-migration.py: Remove trick on parsing ramblocks, peterx, 2024/01/28
- [PULL 04/14] migration: Drop unnecessary check in ram's pending_exact(), peterx, 2024/01/28
- [PULL 06/14] ci: Add a migration compatibility test job, peterx, 2024/01/28
- [PULL 07/14] ci: Disable migration compatibility tests for aarch64, peterx, 2024/01/28
- [PULL 08/14] migration/yank: Use channel features, peterx, 2024/01/28
- [PULL 09/14] migration: Fix use-after-free of migration state object, peterx, 2024/01/28
- [PULL 10/14] migration: Take reference to migration state around bg_migration_vm_start_bh, peterx, 2024/01/28
- [PULL 11/14] migration: Reference migration state around loadvm_postcopy_handle_run_bh, peterx, 2024/01/28
- [PULL 12/14] migration: Add a wrapper to qemu_bh_schedule, peterx, 2024/01/28
- [PULL 13/14] migration: Centralize BH creation and dispatch,
peterx <=
- [PULL 14/14] Make 'uri' optional for migrate QAPI, peterx, 2024/01/28
- Re: [PULL 00/14] Migration 20240126 patches, Peter Maydell, 2024/01/29