Re: [PATCH] Relay : fix cpu offline problem

[Lai Jiangshan <laijs@cn.fujitsu.com>]

Hi, Mathieu Desnoyers

I have fixed this problem in mainline.
http://lkml.org/lkml/2008/11/14/74

Lai

Mathieu Desnoyers wrote:
> Here is a fix for how relay handles cpu hotplug in the allocation error path. If
> a cpu goes down while allocating, it may result in a buffer never being freed.
> 
> Lai Jiangshan originally identified this problem in the LTTng fork of
> relay (ltt-relay-alloc). Here is the fix which applies to the original
> kernel/relay.c.
> 
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
> CC: Lai Jiangshan <laijs@cn.fujitsu.com>
> CC: Tom Zanussi <zanussi@comcast.net>
> ---
>  kernel/relay.c |    7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> Index: linux-2.6-lttng/kernel/relay.c
> ===================================================================
> --- linux-2.6-lttng.orig/kernel/relay.c	2008-12-09 10:58:45.000000000 -0500
> +++ linux-2.6-lttng/kernel/relay.c	2008-12-09 11:09:58.000000000 -0500
> @@ -611,10 +611,9 @@ struct rchan *relay_open(const char *bas
>  	return chan;
>  
>  free_bufs:
> -	for_each_online_cpu(i) {
> -		if (!chan->buf[i])
> -			break;
> -		relay_close_buf(chan->buf[i]);
> +	for_each_possible_cpu(i) {
> +		if (chan->buf[i])
> +			relay_close_buf(chan->buf[i]);
>  	}
>  
>  	kref_put(&chan->kref, relay_destroy_channel);