Re: [PATCH tip/core/rcu 02/14] rcu: Consolidate duplicate callback-list initialization

Josh Triplett
2012-06-15T20:42:32Z

On Fri, Jun 15, 2012 at 01:13:03PM -0700, Paul E. McKenney wrote:
> From: "Paul E. McKenney" <paul.mckenney@linaro.org>
>
> There are a couple of open-coded initializations of the rcu_data
> structure's RCU callback list. This commit therefore consolidates
> them into a new init_callback_list() function.
>
> Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

Reviewed-by: Josh Triplett <josh@joshtriplett.org>

> kernel/rcutree.c | 23 ++++++++++++++---------
> 1 files changed, 14 insertions(+), 9 deletions(-)
>
> diff --git a/kernel/rcutree.c b/kernel/rcutree.c
> index 0f04480..d938671 100644
> --- a/kernel/rcutree.c
> +++ b/kernel/rcutree.c
> @@ -936,6 +936,18 @@ check_for_new_grace_period(struct rcu_state *rsp, struct rcu_data *rdp)
> }
>
> /*
> + * Initialize the specified rcu_data structure's callback list to empty.
> + */
> +static void init_callback_list(struct rcu_data *rdp)
> +{
> + int i;
> +
> + rdp->nxtlist = NULL;
> + for (i = 0; i < RCU_NEXT_SIZE; i++)
> + rdp->nxttail[i] = &rdp->nxtlist;
> +}
> +
> +/*
> * Advance this CPU's callbacks, but only if the current grace period
> * has ended. This may be called only from the CPU to whom the rdp
> * belongs. In addition, the corresponding leaf rcu_node structure's
> @@ -1327,8 +1339,6 @@ static void
> rcu_send_cbs_to_orphanage(int cpu, struct rcu_state *rsp,
> struct rcu_node *rnp, struct rcu_data *rdp)
> {
> - int i;
> -
> /*
> * Orphan the callbacks. First adjust the counts. This is safe
> * because ->onofflock excludes _rcu_barrier()'s adoption of
> @@ -1368,9 +1378,7 @@ rcu_send_cbs_to_orphanage(int cpu, struct rcu_state *rsp,
> }
>
> /* Finally, initialize the rcu_data structure's list to empty. */
> - rdp->nxtlist = NULL;
> - for (i = 0; i < RCU_NEXT_SIZE; i++)
> - rdp->nxttail[i] = &rdp->nxtlist;
> + init_callback_list(rdp);
> }
>
> /*
> @@ -2404,16 +2412,13 @@ static void __init
> rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
> {
> unsigned long flags;
> - int i;
> struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
> struct rcu_node *rnp = rcu_get_root(rsp);
>
> /* Set up local state, ensuring consistent view of global state. */
> raw_spin_lock_irqsave(&rnp->lock, flags);
> rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo);
> - rdp->nxtlist = NULL;
> - for (i = 0; i < RCU_NEXT_SIZE; i++)
> - rdp->nxttail[i] = &rdp->nxtlist;
> + init_callback_list(rdp);
> rdp->qlen_lazy = 0;
> rdp->qlen = 0;
> rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
> --
> 1.7.8
>