[PATCH] relay: fix cpu offline problem

[PATCH] relay: fix cpu offline problem

[Lai Jiangshan]

relay_open() will close allocated buffers when failed.
but if cpu offlined, some buffer will not be closed.
this patch fixed it.

and did cleanup for relay_reset() too.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
diff --git a/kernel/relay.c b/kernel/relay.c
index 8d13a78..32b0bef 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -400,7 +400,7 @@ void relay_reset(struct rchan *chan)
 	}
 
 	mutex_lock(&relay_channels_mutex);
-	for_each_online_cpu(i)
+	for_each_possible_cpu(i)
 		if (chan->buf[i])
 			__relay_reset(chan->buf[i], 0);
 	mutex_unlock(&relay_channels_mutex);
@@ -611,10 +611,9 @@ struct rchan *relay_open(const char *base_filename,
 	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);

Re: [PATCH] relay: fix cpu offline problem

[Jens Axboe]

On Fri, Nov 14 2008, Lai Jiangshan wrote:
> relay_open() will close allocated buffers when failed.
> but if cpu offlined, some buffer will not be closed.
> this patch fixed it.
> 
> and did cleanup for relay_reset() too.

Good catch, that definitely looks like a bug. Applied.

> 
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
> ---
> diff --git a/kernel/relay.c b/kernel/relay.c
> index 8d13a78..32b0bef 100644
> --- a/kernel/relay.c
> +++ b/kernel/relay.c
> @@ -400,7 +400,7 @@ void relay_reset(struct rchan *chan)
>  	}
>  
>  	mutex_lock(&relay_channels_mutex);
> -	for_each_online_cpu(i)
> +	for_each_possible_cpu(i)
>  		if (chan->buf[i])
>  			__relay_reset(chan->buf[i], 0);
>  	mutex_unlock(&relay_channels_mutex);
> @@ -611,10 +611,9 @@ struct rchan *relay_open(const char *base_filename,
>  	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);
> 

-- 
Jens Axboe

[PATCH] Relay : fix cpu offline problem

[Mathieu Desnoyers]

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);
-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

Re: [PATCH] Relay : fix cpu offline problem

[Lai Jiangshan]

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);

Re: [PATCH] Relay : fix cpu offline problem

[Mathieu Desnoyers]

Ah, great, I did not see it passing by. Thanks !

Mathieu

* Lai Jiangshan (laijs@cn.fujitsu.com) wrote:
> 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);
> 
> 

-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68