lkml.org 
[lkml]   [2012]   [Sep]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH tip/core/rcu 10/15] rcu: Protect rcu_node accesses during CPU stall warnings
From
Date
On Thu, 2012-08-30 at 11:56 -0700, Paul E. McKenney wrote:
> From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
>
> The print_other_cpu_stall() function accesses a number of rcu_node
> fields without protection from the ->lock. In theory, this is not
> a problem because the fields accessed are all integers, but in
> practice the compiler can get nasty. Therefore, the commit extends
> the existing critical section to cover the entire loop body.
>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> ---
> kernel/rcutree.c | 6 ++++--
> 1 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/rcutree.c b/kernel/rcutree.c
> index 9f44749..fbe43b0 100644
> --- a/kernel/rcutree.c
> +++ b/kernel/rcutree.c
> @@ -746,14 +746,16 @@ static void print_other_cpu_stall(struct rcu_state *rsp)
> rcu_for_each_leaf_node(rsp, rnp) {
> raw_spin_lock_irqsave(&rnp->lock, flags);
> ndetected += rcu_print_task_stall(rnp);
> - raw_spin_unlock_irqrestore(&rnp->lock, flags);
> - if (rnp->qsmask == 0)
> + if (rnp->qsmask == 0) {
> + raw_spin_unlock_irqrestore(&rnp->lock, flags);
> continue;
> + }
> for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++)
> if (rnp->qsmask & (1UL << cpu)) {
> print_cpu_stall_info(rsp, rnp->grplo + cpu);
> ndetected++;
> }
> + raw_spin_unlock_irqrestore(&rnp->lock, flags);
> }

You now cover printk() and all that that can call with a RCU lock.. is
this a good thing?


\
 
 \ /
  Last update: 2012-09-06 17:42    [W:0.370 / U:0.476 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site