[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v6 02/11] libxl_qmp: Separate QMP message generation from qmp_send_prepare
Anthony PERARD writes ("Re: [PATCH v6 02/11] libxl_qmp: Separate QMP message generation from qmp_send_prepare"): > On Mon, Nov 12, 2018 at 05:20:53PM +0000, Ian Jackson wrote: > > Previously this function returned memory allocated from malloc, and > > this was not documented. I think it should be, for both this and for > > qmp_prepare_cmd. See the big libxl.h comment on "memory allocation". > > The memory allocated from malloc is new, before that it was allocated in > `gc` (aside from the `yajl_gen hand` which needs to be freed before the > function returns). Right. I was asking for this to be documented in a comment, as required by the libxl error handling model. > I've make the change to return a NOGC buffers because I don't know how > to have an allocation survive an `egc`. Indeed, an egc's allocation would be too short. > Do you think I could call qmp_send_prepare with an `ao_gc` ? Not in this > patch, but later, in the context of libxl__ev_qmp which I think > shouldn't survive an AO. Ah yes, I keep thinking that you could cache a libxl__ev_qmp in the libxl_ctx but because qemu will only talk on one at once, you are right. So yes a libxl__ev_qmp should have a reference to an ao. Then you can use the ao gc. > > 1 is wanted because 2 demands it. > > I'll try to improve the patch description and awnser all those things. Thanks. > > 4 ??? The existing code uses strlen. JSON can't contain nul bytes. > > Why should the new caller not do similarly ? If the use of strlen is > > wrong why not change the old caller ? (Maybe it is going away, in > > which case that needs to be mentioned.) > > I guess I can recalculate the lenght at the time when it will be needed > in a later patch. Or something. I just noticed that this was done differently in different places. It's probably more convenient to recalculate it than it is to carry it about. But I don't mind if you want to carry it about - but in that case I think you should switch all the callers to using the length returned by qmp_prepare_cmd. Thanks, Ian. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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