Re: [PATCH 02/20] mm: Add optional TLB flush to generic RCU page-table freeing

[Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>]

On Wed, Jun 27, 2012 at 4:01 PM, Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote:
>
> How about something like this

Looks better.

I'd be even happier if you made the whole

  "When there's less then two users.."

(There's a misspelling there, btw, I didn't notice until I
cut-and-pasted that) logic be a helper function, and have that helper
function be inside that same #ifdef CONFIG_STRICT_TLB_FILL block
together witht he tlb_table_flush_mmu() function.

IOW, something like

  static int tlb_remove_table_quick( struct mmu_gather *tlb, void *table)
  {
        if (atomic_read(&tlb->mm->mm_users) < 2) {
            __tlb_remove_table(table);
            return 1;
        }
        return 0;
  }

for the CONFIG_STRICT_TLB_FILL case, and then the default case just
does an unconditional "return 0".

So that the actual code can avoid having #ifdef's in the middle of a
function, and could just do

    if (tlb_remove_table_quick(tlb, table))
        return;

instead.

Maybe it's just me, but I detest seeing #ifdef's in the middle of
code. I'd much rather have the #ifdef's *outside* the code and have
these kinds of helper functions that sometimes end up becoming empty.

                   Linus
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