On Mon, Jun 5, 2017 at 3:40 PM, Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> I think the "LDT didn't match" was really just a simpler and more
> efficient way to say "they weren't both NULL".
In fact, looking back in the history, it used to instead add the sizes
of the context (and then similar logic: "if the sum is non-zero, one
or the other was non-zero").
Commit 0bbed3beb4 ("[PATCH] Thread-Local Storage (TLS) support") in
the historical tree then did this:
- if (next->context.size+prev->context.size)
+ if (unlikely(prev->context.ldt != next->context.ldt))
I'm ok with your change, but I reacted to the commit log about how
this was "overcomplicated". It was actually an optimization exactly to
avoid two compares..
Linus
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