On Tue, 1 Aug 2023 at 15:07, Suren Baghdasaryan surenb@google.com wrote:
To make locking more visible, change thesefunctions to assert that the vma write lock is taken and explicitly lock the vma beforehand.
So I obviously think this is a good change, but the fact that it touched driver files makes me go "we're still doing something wrong".
I'm not super-happy with hfi1_file_mmap() doing something like vma_start_write(), in that I *really* don't think drivers should ever have to think about issues like this.
And I think it's unnecessary. This is the mmap op in the hfi1_file_ops, and I think that any actual mmap() code had _better_ had locked the new vma before asking any driver to set things up (and the assert would catch it if somebody didn't).
I realize that it doesn't hurt in a technical sense, but I think having drivers call these VM-internal subtle locking functions does hurt in a maintenance sense, so we should make sure to not have it.
Linus