From 6e48e8f9e0f5b6b15c41f6f8a68c9bf330147d45 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Tue, 10 Feb 2015 10:25:44 -0700 Subject: memory: unregister AddressSpace MemoryListener within BQL address_space_destroy_dispatch is called from an RCU callback and hence outside the iothread mutex (BQL). However, after address_space_destroy no new accesses can hit the destroyed AddressSpace so it is not necessary to observe changes to the memory map. Move the memory_listener_unregister call earlier, to make it thread-safe again. Reported-by: Alex Williamson Fixes: 374f2981d1f10bc4307f250f24b2a7ddb9b14be0 Signed-off-by: Paolo Bonzini Signed-off-by: Alex Williamson --- exec.c | 6 +++++- include/exec/memory-internal.h | 1 + memory.c | 1 + 3 files changed, 7 insertions(+), 1 deletion(-) diff --git a/exec.c b/exec.c index 6b79ad1..6dff7bc 100644 --- a/exec.c +++ b/exec.c @@ -2059,11 +2059,15 @@ void address_space_init_dispatch(AddressSpace *as) memory_listener_register(&as->dispatch_listener, as); } +void address_space_unregister(AddressSpace *as) +{ + memory_listener_unregister(&as->dispatch_listener); +} + void address_space_destroy_dispatch(AddressSpace *as) { AddressSpaceDispatch *d = as->dispatch; - memory_listener_unregister(&as->dispatch_listener); g_free(d); as->dispatch = NULL; } diff --git a/include/exec/memory-internal.h b/include/exec/memory-internal.h index 25c43c0..fb467ac 100644 --- a/include/exec/memory-internal.h +++ b/include/exec/memory-internal.h @@ -23,6 +23,7 @@ typedef struct AddressSpaceDispatch AddressSpaceDispatch; void address_space_init_dispatch(AddressSpace *as); +void address_space_unregister(AddressSpace *as); void address_space_destroy_dispatch(AddressSpace *as); extern const MemoryRegionOps unassigned_mem_ops; diff --git a/memory.c b/memory.c index 9b91243..130152c 100644 --- a/memory.c +++ b/memory.c @@ -1978,6 +1978,7 @@ void address_space_destroy(AddressSpace *as) as->root = NULL; memory_region_transaction_commit(); QTAILQ_REMOVE(&address_spaces, as, address_spaces_link); + address_space_unregister(as); /* At this point, as->dispatch and as->current_map are dummy * entries that the guest should never use. Wait for the old -- cgit v1.1