Re: [Qemu-devel] [PATCH v2] hostmem: Fix qemu_opt_get_bool() crash in host_memory_backend_init()

[Marcel Apfelbaum <marcel@redhat.com>]

On 07/20/2015 11:15 PM, Eduardo Habkost wrote:
> This fixes the following crash, introduced by commit
> 49d2e648e8087d154d8bf8b91f27c8e05e79d5a6:
>
>    $ gdb --args qemu-system-x86_64 -machine pc,mem-merge=off -object memory-backend-ram,id=ram-node0,size=1024
>    [...]
>    Program received signal SIGABRT, Aborted.
>    (gdb) bt
>    #0  0x00007ffff253b8c7 in raise () at /lib64/libc.so.6
>    #1  0x00007ffff253d52a in abort () at /lib64/libc.so.6
>    #2  0x00007ffff253446d in __assert_fail_base () at /lib64/libc.so.6
>    #3  0x00007ffff2534522 in  () at /lib64/libc.so.6
>    #4  0x00005555558bb80a in qemu_opt_get_bool_helper (opts=0x55555621b650, name=name@entry=0x5555558ec922 "mem-merge", defval=defval@entry=true, del=del@entry=false) at qemu/util/qemu-option.c:388
>    #5  0x00005555558bbb5a in qemu_opt_get_bool (opts=<optimized out>, name=name@entry=0x5555558ec922 "mem-merge", defval=defval@entry=true) at qemu/util/qemu-option.c:398
>    #6  0x0000555555720a24 in host_memory_backend_init (obj=0x5555562ac970) at qemu/backends/hostmem.c:226
>
> Instead of using qemu_opt_get_bool(), that didn't work with
> qemu_machine_opts for a long time, we can use the corresponding
> MachineState fields.
>
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
> Changes v1 -> v2:
> * Use qdev_get_machine() instead of current_machine
> * Use the MachineState field wrappers intead of QOM properties,
>    to allow compile-time type checks
> ---
>   backends/hostmem.c | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/backends/hostmem.c b/backends/hostmem.c
> index 61c1ac0..41ba2af 100644
> --- a/backends/hostmem.c
> +++ b/backends/hostmem.c
> @@ -10,6 +10,7 @@
>    * See the COPYING file in the top-level directory.
>    */
>   #include "sysemu/hostmem.h"
> +#include "hw/boards.h"
>   #include "qapi/visitor.h"
>   #include "qapi-types.h"
>   #include "qapi-visit.h"
> @@ -222,11 +223,10 @@ static void host_memory_backend_set_prealloc(Object *obj, bool value,
>   static void host_memory_backend_init(Object *obj)
>   {
>       HostMemoryBackend *backend = MEMORY_BACKEND(obj);
> +    MachineState *machine = MACHINE(qdev_get_machine());
>
> -    backend->merge = qemu_opt_get_bool(qemu_get_machine_opts(),
> -                                       "mem-merge", true);
> -    backend->dump = qemu_opt_get_bool(qemu_get_machine_opts(),
> -                                      "dump-guest-core", true);
> +    backend->merge = machine_mem_merge(machine);
> +    backend->dump = machine_dump_guest_core(machine);
>       backend->prealloc = mem_prealloc;
>
>       object_property_add_bool(obj, "merge",
>

Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>