On Mon, Jan 20, 2014 at 5:24 PM, Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx> wrote:
> From: Jason Low <jason.low2@xxxxxx>
> @@ -41,8 +47,11 @@ void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
>
> prev = xchg(lock, node);
> if (likely(prev == NULL)) {
> - /* Lock acquired */
> - node->locked = 1;
> + /* Lock acquired, don't need to set node->locked to 1
> + * as lock owner and other contenders won't check this value.
> + * If a debug mode is needed to audit lock status, then
> + * set node->locked value here.
> + */
It would also be good to mention why the value is not checked
in this comment. Perhaps something like the following:
/*
* Lock acquired, don't need to set node->locked to 1. Threads
* only spin on its own node->locked value for lock acquisition.
* However, since this thread can immediately acquire the lock
* and does not proceed to spin on its own node->locked, this
* value won't be used. If a debug mode is needed to
* audit lock status, then set node->locked value here.
*/
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