This is a follow up of below patch from Avihai as a replacement: https://lore.kernel.org/qemu-devel/20241020130108.27148-3-avih...@nvidia.com/
This is v2 of the series, and it became a more generic rework on how we do migration object refcounts, so I skipped a changelog because most of this is new things. To put it simple, now I introduced another pointer to migration object, and here's a simple explanation for both after all change applied (copy-paste from one of the patch): /* * We have two pointers for the global migration objects. Both of them are * initialized early during QEMU starts, but they have different lifecycles. * * - current_migration * * This variable reflects the whole lifecycle of the migration object * (which each QEMU can only have one). It is valid until the migration * object is destroyed. * * This is the object that internal migration so far use. For example, * internal helper migrate_get_current() references it. * * When all migration code can always pass over a MigrationState* around, * this variable can logically be dropped. But we're not yet there. * * - global_migration * * This is valid only until the migration object is still valid to the * outside-migration world (until migration_shutdown()). * * This should normally be always set, cleared or accessed by the main * thread only, rather than the migration thread. * * All the exported functions (in include/migration) should reference the * exported migration object only to avoid race conditions, as * current_migration can be freed concurrently by migration thread when * the migration thread holds the last refcount. */ It allows all misc.h exported helpers to be used for the whole VM lifecycle, so as to never crash QEMU with freed migration objects. Thanks, Peter Xu (4): migration: Unexport dirty_bitmap_mig_init() in misc.h migration: Reset current_migration properly migration: Add global_migration migration: Make all helpers in misc.h safe to use without migration include/migration/misc.h | 29 ++++++++---- migration/migration.h | 4 ++ migration/migration.c | 99 +++++++++++++++++++++++++++++++++++----- 3 files changed, 113 insertions(+), 19 deletions(-) -- 2.45.0
