On Tue, 02/23 10:42, Paolo Bonzini wrote: > > > On 23/02/2016 06:39, Fam Zheng wrote: > > BTW, could you also explain the blk_mig_lock() question (*) I had? > > > > *: https://lists.gnu.org/archive/html/qemu-devel/2016-02/msg03317.html > > Sorry, missed that: > > > > >> @@ -597,21 +627,28 @@ static void block_migration_cleanup(void *opaque) > >> { > >> BlkMigDevState *bmds; > >> BlkMigBlock *blk; > >> + AioContext *ctx; > >> > >> bdrv_drain_all(); > >> > >> unset_dirty_tracking(); > >> > >> - blk_mig_lock(); > > > > Why is it okay to skip the blk_mig_lock() for block_mig_state.bmds_list? > > The bmds_list is not protected by blk_mig_lock: > > /* Written during setup phase. Can be read without a lock. */ > int blk_enable; > int shared_base; > QSIMPLEQ_HEAD(bmds_list, BlkMigDevState) bmds_list; > int64_t total_sector_sum; > bool zero_blocks; > > block_migration_cleanup is called from qemu_savevm_state_cleanup, when > there can be no concurrency between the migration thread and the I/O > thread. In fact the call of qemu_savevm_state_cleanup might as well be > moved out of the migration thread.
Thanks! Fam
