Re: [PATCH tip/core/rcu 15/23] rcu: Make rcutree module parametersvisible in sysfs

From: Josh Triplett
Date: Mon Sep 03 2012 - 05:32:28 EST


On Thu, Aug 30, 2012 at 11:18:30AM -0700, Paul E. McKenney wrote:
> From: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
>
> The module parameters blimit, qhimark, and qlomark (and more
> recently, rcu_fanout_leaf) have permission masks of zero, so
> that their values are not visible from sysfs. This is unnecessary
> and inconvenient to administrators who might like an easy way to
> see what these values are on a running system. This commit therefore
> sets their permission masks to 0444, allowing them to be read but
> not written.
>
> Reported-by: Rusty Russell <rusty@xxxxxxxxxx>
> Reported-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>

Reviewed-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx>

> kernel/rcutree.c | 8 ++++----
> 1 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/rcutree.c b/kernel/rcutree.c
> index 1d33240..55f20fd 100644
> --- a/kernel/rcutree.c
> +++ b/kernel/rcutree.c
> @@ -88,7 +88,7 @@ LIST_HEAD(rcu_struct_flavors);
>
> /* Increase (but not decrease) the CONFIG_RCU_FANOUT_LEAF at boot time. */
> static int rcu_fanout_leaf = CONFIG_RCU_FANOUT_LEAF;
> -module_param(rcu_fanout_leaf, int, 0);
> +module_param(rcu_fanout_leaf, int, 0444);
> int rcu_num_lvls __read_mostly = RCU_NUM_LVLS;
> static int num_rcu_lvl[] = { /* Number of rcu_nodes at specified level. */
> NUM_RCU_LVL_0,
> @@ -216,9 +216,9 @@ static int blimit = 10; /* Maximum callbacks per rcu_do_batch. */
> static int qhimark = 10000; /* If this many pending, ignore blimit. */
> static int qlowmark = 100; /* Once only this many pending, use blimit. */
>
> -module_param(blimit, int, 0);
> -module_param(qhimark, int, 0);
> -module_param(qlowmark, int, 0);
> +module_param(blimit, int, 0444);
> +module_param(qhimark, int, 0444);
> +module_param(qlowmark, int, 0444);
>
> int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */
> int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT;
> --
> 1.7.8
>
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