Re: [PATCH 2/9] rcu: Remove superfluous local variable in rcu_init_geometry()

From: Paul E. McKenney
Date: Sat Mar 07 2015 - 13:03:49 EST


On Sat, Mar 07, 2015 at 06:03:37PM +0100, Alexander Gordeev wrote:
> Local variable 'n' mimics 'nr_cpu_ids' while the both are
> used within one function. There is no reason for 'n' to
> exist whatsoever.
>
> Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Alexander Gordeev <agordeev@xxxxxxxxxx>

Good catch! Could you please port this to branch rcu/next of
git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git?

Thanx, Paul

> ---
> kernel/rcu/tree.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 7588c7f..fb89630 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -3855,7 +3855,6 @@ static void __init rcu_init_geometry(void)
> ulong d;
> int i;
> int j;
> - int n = nr_cpu_ids;
> int rcu_capacity[MAX_RCU_LVLS + 1];
>
> /*
> @@ -3898,7 +3897,7 @@ static void __init rcu_init_geometry(void)
> * the rcu_node masks. Complain and fall back to the compile-
> * time values if these limits are exceeded.
> */
> - if (n > rcu_capacity[MAX_RCU_LVLS])
> + if (nr_cpu_ids > rcu_capacity[MAX_RCU_LVLS])
> panic("rcu_init_geometry: rcu_capacity[] is too small");
> else if (rcu_fanout_leaf < CONFIG_RCU_FANOUT_LEAF ||
> rcu_fanout_leaf > sizeof(unsigned long) * 8) {
> @@ -3908,10 +3907,11 @@ static void __init rcu_init_geometry(void)
>
> /* Calculate the number of rcu_nodes at each level of the tree. */
> for (i = 1; i <= MAX_RCU_LVLS; i++)
> - if (n <= rcu_capacity[i]) {
> - for (j = 0; j <= i; j++)
> - num_rcu_lvl[j] =
> - DIV_ROUND_UP(n, rcu_capacity[i - j]);
> + if (nr_cpu_ids <= rcu_capacity[i]) {
> + for (j = 0; j <= i; j++) {
> + int cap = rcu_capacity[i - j];
> + num_rcu_lvl[j] = DIV_ROUND_UP(nr_cpu_ids, cap);
> + }
> rcu_num_lvls = i;
> for (j = i + 1; j <= MAX_RCU_LVLS; j++)
> num_rcu_lvl[j] = 0;
> @@ -3922,7 +3922,7 @@ static void __init rcu_init_geometry(void)
> rcu_num_nodes = 0;
> for (i = 0; i <= MAX_RCU_LVLS; i++)
> rcu_num_nodes += num_rcu_lvl[i];
> - rcu_num_nodes -= n;
> + rcu_num_nodes -= nr_cpu_ids;
> }
>
> void __init rcu_init(void)
> --
> 1.8.3.1
>

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