Re: [PATCH/RFC] mutex: Fix optimistic spinning vs. BKL

[Arnd Bergmann]

On Wednesday 28 April 2010, Benjamin Herrenschmidt wrote:
> Now, we -could- make it a bit smarter about the BKL by introducing a
> contention counter and only go out if we own the BKL and it is contended,
> but I didn't feel like this was worth the effort, time is better spent
> removing the BKL from sensitive code path instead.

Agreed.

> -       for (;;) {
> +       for (timeout = jiffies + 2; jiffies < timeout;) {
> [...]
> -       for (;;) {
> +       while (jiffies < timeout) {

This needs to use time_before() to avoid problems on jiffies wraparound.

	Arnd
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