Re: [PATCH] mm: introduce for_each_vma helpers

Kirill A. Shutemov
2014-08-12T21:53:26Z

On Tue, Aug 12, 2014 at 10:45:23AM -0700, Davidlohr Bueso wrote:
> The most common way of iterating through the list of vmas, is via:
> for (vma = mm->mmap; vma; vma = vma->vm_next)
>
> This patch replaces this logic with a new for_each_vma(vma) helper,
> which 1) encapsulates this logic, and 2) make it easier to read.

Why does it need to be encapsulated?
Do you have problem with reading plain for()?

Your for_each_vma(vma) assumes "mm" from the scope. This can be confusing
for reader: whether it uses "mm" from the scope or "current->mm". This
will lead to very hard to find bug one day.
I don't like this.

> It also updates most of the callers, so its a pretty good start.
>
> Similarly, we also have for_each_vma_start(vma, start) when the user
> does not want to start at the beginning of the list. And lastly the
> for_each_vma_start_inc(vma, start, inc) helper in introduced to allow
> users to create higher level special vma abstractions, such as with
> the case of ELF binaries.

for_each_vma_start_inc() is pretty much the plain for() but with
really_long_and_fancy_name(). Why?

--
Kirill A. Shutemov