Re: [Qemu-devel] [PATCH v2] qemu_opt_foreach: Fix crasher

[Peter Maydell]

On 6 October 2016 at 14:02, Peter Maydell <address@hidden> wrote:
> On 6 October 2016 at 13:39, Michal Privoznik <address@hidden> wrote:
>> diff --git a/include/sysemu/char.h b/include/sysemu/char.h
>> index 0d0465a..df58ef8 100644
>> --- a/include/sysemu/char.h
>> +++ b/include/sysemu/char.h
>> @@ -93,6 +93,7 @@ struct CharDriverState {
>>      int avail_connections;
>>      int is_mux;
>>      guint fd_in_tag;
>> +    /* Be aware that in some cases @opts might be NULL. */
>>      QemuOpts *opts;
>>      bool replay;
>>      QTAILQ_ENTRY(CharDriverState) next;
>
> Wouldn't it be better to ensure that it can't be NULL regardless of
> how the object was created?

FWIW, a quick check of who uses this field (by commenting it out
and looking for the compile errors) shows:
 net/vhost-user.c
 net/colo-compare.c (which also just does a foreach on it)
 qemu-char.c (in qemu_chr_new_from_opts and qemu_chr_free_common)

Alternative possible approach: if you can create a CharDriver
validly with no opts, then the net/ code shouldn't be looking
at opts at all (but should instead look at wherever the config
stuff goes for the 'opts is null' case, which we should make
sure is correct regardless of how the CharDriver was created).

thanks
-- PMM