linux-kernel - Re: [PATCH tip/core/rcu 6/7] rcu: Move early-boot callbacks to no-CBs lists for no-CBs CPUs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 3 Mar 2015 16:57:16 +0000 (UTC)
From:	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc:	linux-kernel@...r.kernel.org, mingo@...nel.org,
	laijs@...fujitsu.com, dipankar@...ibm.com,
	akpm@...ux-foundation.org, josh@...htriplett.org,
	tglx@...utronix.de, peterz@...radead.org, rostedt@...dmis.org,
	dhowells@...hat.com, edumazet@...gle.com, dvhart@...ux.intel.com,
	fweisbec@...il.com, oleg@...hat.com,
	bobby prani <bobby.prani@...il.com>
Subject: Re: [PATCH tip/core/rcu 6/7] rcu: Move early-boot callbacks to
 no-CBs lists for no-CBs CPUs

----- Original Message -----
> From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
> To: linux-kernel@...r.kernel.org
> Cc: mingo@...nel.org, laijs@...fujitsu.com, dipankar@...ibm.com, akpm@...ux-foundation.org, "mathieu desnoyers"
> <mathieu.desnoyers@...icios.com>, josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
> rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com, dvhart@...ux.intel.com, fweisbec@...il.com,
> oleg@...hat.com, "bobby prani" <bobby.prani@...il.com>, "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
> Sent: Tuesday, March 3, 2015 11:45:47 AM
> Subject: [PATCH tip/core/rcu 6/7] rcu: Move early-boot callbacks to no-CBs lists for no-CBs CPUs
> 
> From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
> 
> When a CPU is first determined to be a no-CBs CPUs, this commit causes
> any early boot callbacks to be moved to the no-CBs callback list,
> allowing them t obe invoked.
                ^^^^^
out-of-order space ;)

Thanks,

Mathieu

> 
> Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
> ---
>  kernel/rcu/tree.c        |  1 +
>  kernel/rcu/tree_plugin.h | 24 ++++++++++++------------
>  2 files changed, 13 insertions(+), 12 deletions(-)
> 
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 92fd3eab5823..0317bf7d997f 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -2851,6 +2851,7 @@ __call_rcu(struct rcu_head *head, void (*func)(struct
> rcu_head *rcu),
>  		 * and then drop through to queue the callback.
>  		 */
>  		BUG_ON(cpu != -1);
> +		WARN_ON_ONCE(!rcu_is_watching());
>  		if (!likely(rdp->nxtlist))
>  			init_default_callback_list(rdp);
>  	}
> diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
> index 75d5f096bcb0..afddd5641bea 100644
> --- a/kernel/rcu/tree_plugin.h
> +++ b/kernel/rcu/tree_plugin.h
> @@ -2393,18 +2393,8 @@ void __init rcu_init_nohz(void)
>  		pr_info("\tPoll for callbacks from no-CBs CPUs.\n");
>  
>  	for_each_rcu_flavor(rsp) {
> -		for_each_cpu(cpu, rcu_nocb_mask) {
> -			struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
> -
> -			/*
> -			 * If there are early callbacks, they will need
> -			 * to be moved to the nocb lists.
> -			 */
> -			WARN_ON_ONCE(rdp->nxttail[RCU_NEXT_TAIL] !=
> -				     &rdp->nxtlist &&
> -				     rdp->nxttail[RCU_NEXT_TAIL] != NULL);
> -			init_nocb_callback_list(rdp);
> -		}
> +		for_each_cpu(cpu, rcu_nocb_mask)
> +			init_nocb_callback_list(per_cpu_ptr(rsp->rda, cpu));
>  		rcu_organize_nocb_kthreads(rsp);
>  	}
>  }
> @@ -2541,6 +2531,16 @@ static bool init_nocb_callback_list(struct rcu_data
> *rdp)
>  	if (!rcu_is_nocb_cpu(rdp->cpu))
>  		return false;
>  
> +	/* If there are early-boot callbacks, move them to nocb lists. */
> +	if (rdp->nxtlist) {
> +		rdp->nocb_head = rdp->nxtlist;
> +		rdp->nocb_tail = rdp->nxttail[RCU_NEXT_TAIL];
> +		atomic_long_set(&rdp->nocb_q_count, rdp->qlen);
> +		atomic_long_set(&rdp->nocb_q_count_lazy, rdp->qlen_lazy);
> +		rdp->nxtlist = NULL;
> +		rdp->qlen = 0;
> +		rdp->qlen_lazy = 0;
> +	}
>  	rdp->nxttail[RCU_NEXT_TAIL] = NULL;
>  	return true;
>  }
> --
> 1.8.1.5
> 
> 

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/