Re: [PATCH v7 1/4] spinlock: A new lockref structure for locklessupdate of refcount

[Linus Torvalds]

On Tue, Sep 3, 2013 at 8:14 AM, Waiman Long <waiman.long@xxxxxx> wrote:
>
> Other than the global tty_ldisc_lock, there is no other major
> bottleneck. I am not that worry about the tty_ldisc_lock bottleneck
> as real world applications probably won't have that many calls to
> set the tty driver.

I suspect the tty_ldisc_lock() could be made to go away if we care.
Making the ldisc be rcu-free'd, coupled with just optimistically
updating the count using "atomic_inc_not_zero()" and re-checking the
ldisc pointer afterwards should probably do it. But I agree that it
probably isn't worth it for any actual real load.

              Linus
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