Commit 6e48e8f9 authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Alex Williamson
Browse files

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: default avatarAlex Williamson <alex.williamson@redhat.com>
Fixes: 374f2981
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent a2f2d288

exec.c

+5 −1
Original line number Diff line number Diff line
@@ -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;

}

include/exec/memory-internal.h

+1 −0
Original line number Diff line number Diff line
@@ -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;

memory.c

+1 −0
Original line number Diff line number Diff line
@@ -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