On Tue, Oct 06, 2015 at 09:29:23AM -0700, Paul E. McKenney wrote:
> +/* Flags for rcu_preempt_ctxt_queue() decision table. */
> +#define RCU_GP_TASKS 0x8
> +#define RCU_EXP_TASKS 0x4
> +#define RCU_GP_BLKD 0x2
> +#define RCU_EXP_BLKD 0x1
Purely cosmetic, but that's backwards ;-) Most of our flags etc.. are in
increasing order.
> +static void rcu_preempt_ctxt_queue(struct rcu_node *rnp, struct rcu_data
> *rdp,
> + unsigned long flags) __releases(rnp->lock)
> +{
> + int blkd_state = (rnp->gp_tasks ? RCU_GP_TASKS : 0) +
> + (rnp->exp_tasks ? RCU_EXP_TASKS : 0) +
> + (rnp->qsmask & rdp->grpmask ? RCU_GP_BLKD : 0) +
> + (rnp->expmask & rdp->grpmask ? RCU_EXP_BLKD : 0);
An alternative way is:
int blkd_state = RCU_GP_TASKS * !!rnp->gp_tasks +
RCU_EXP_TASKS * !!rnp->exp_tasks +
RCU_GP_BLKD * !!(rnp->qsmask & rdp->grpmask) +
RCU_EXP_BLKD * !!(rnp->expmask & rdp->grpmask);
I suppose it depends on how your brain is wired which version reads
easier :-)
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