On Wed, 2017-09-20 at 11:34 +0300, Jani Nikula wrote: > On Tue, 19 Sep 2017, Michal Wajdeczko <michal.wajdeczko@xxxxxxxxx> wrote: > > We should discourage developers from modifying modparams. > > Introduce special macro for easier tracking of changes done > > in modparams and enforce its use by defining existing modparams > > members as const. Note that defining whole modparams struct > > as const makes checkpatch unhappy. > > Checkpatch is the least of all reasons to not make the modparams struct > const. > > We can get away with having some fields (such as device info within > dev_priv) const, even if that's dubious. > > IIUC modifying const data is undefined behaviour at best, could cause > subtle bugs through compiler optimizing reads of the data away because > it assumes no modifications, and the data gets placed in rodata at > worst. > > I kinda like the union trick in this patch, but IMO we need to double > check what the standard says about it. Making the fellow developers > check the standard is always a bad sign, even if it turns out to be fine > after all. Here's the snippet to describe the three discussed behaviors. Michal's code seems to do the right thing: https://gcc.godbolt.org/g/6MCNC3 We just need to make the write function stand out more and have a kerneldoc for it. Regards, Joonas -- Joonas Lahtinen Open Source Technology Center Intel Corporation _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
