Messages in this thread | | | Date | Tue, 18 Jan 2022 09:57:45 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH -next, v2] sched: Use struct_size() helper in task_numa_group() |
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On Fri, Jan 14, 2022 at 07:50:47PM -0800, Kees Cook wrote: > On Thu, Jan 13, 2022 at 10:18:57AM +0100, Peter Zijlstra wrote:
> > Then I would still much prefer something like: > > > > unsigned int size = sizeof(*grp) + > > NR_NUMA_HINT_FAULT_STATS * numa_node_ids * sizeof(gfp->faults); > > > > Which is still far more readable than some obscure macro. But again, the > > I'm not sure it's _obscure_, but it is relatively new. It's even > documented. ;) > https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments
I'm one of those people who doesn't read documentation, I read code.
I also flat out refuse to read any documentation that isn't plain text.
> > I can't, nor do I want to, remember all these stupid little macros. Esp. > > not for trivial things like this. > > Well, the good news is that other folks will (and are) fixing them for > you. :) Even if you never make mistakes with flexible arrays, other > people do, and so we need to take on some improvements to the robustness > of the kernel source tree-wide.
But nobody helps me read the code when I trip over crap like this :/ Why do we have to have endless silly helpers for things that can be trivially expressed in regular C? I appreciate things like container_of() because if you write that out it's a mess, but this, very much not so.
struct_size(grp, faults, NR_NUMA_HINT_FAULTS_STATS * numa_node_ids);
vs
sizeof(*gfp) + sizeof(grp->faults) * NR_NUMA_HINT_FAULT_STATS * nr_node_ids;
The latter wins hands down, instantly obvious what it does while with the former I'd have to look up the macro.
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