diff mbox

[net-next,1/2] team: use rcu_access_pointer to access RCU pointer by writer

Message ID 1340206321-5986-2-git-send-email-jpirko@redhat.com
State Superseded, archived
Delegated to: David Miller
Headers show

Commit Message

Jiri Pirko June 20, 2012, 3:32 p.m. UTC
Signed-off-by: Jiri Pirko <jpirko@redhat.com>
---
 drivers/net/team/team_mode_activebackup.c |    7 +++++--
 drivers/net/team/team_mode_loadbalance.c  |    8 +++++---
 2 files changed, 10 insertions(+), 5 deletions(-)

Comments

Eric Dumazet June 20, 2012, 4:01 p.m. UTC | #1
On Wed, 2012-06-20 at 17:32 +0200, Jiri Pirko wrote:
> Signed-off-by: Jiri Pirko <jpirko@redhat.com>
> ---
>  drivers/net/team/team_mode_activebackup.c |    7 +++++--
>  drivers/net/team/team_mode_loadbalance.c  |    8 +++++---
>  2 files changed, 10 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/team/team_mode_activebackup.c b/drivers/net/team/team_mode_activebackup.c
> index 2fe02a8..c9e7621 100644
> --- a/drivers/net/team/team_mode_activebackup.c
> +++ b/drivers/net/team/team_mode_activebackup.c
> @@ -61,8 +61,11 @@ static void ab_port_leave(struct team *team, struct team_port *port)
>  
>  static int ab_active_port_get(struct team *team, struct team_gsetter_ctx *ctx)
>  {
> -	if (ab_priv(team)->active_port)
> -		ctx->data.u32_val = ab_priv(team)->active_port->dev->ifindex;
> +	struct team_port *active_port;
> +
> +	active_port = rcu_access_pointer(ab_priv(team)->active_port);

This is not the correct fix.

You cant safely dereference active_port if you got it from
rcu_access_pointer()

You should use rcu_dereference() of rcu_dereference_protected() or
rcu_dereference_bh() or similar variant, depending on the context.

> +	if (active_port)
> +		ctx->data.u32_val = active_port->dev->ifindex;
>  	else
>  		ctx->data.u32_val = 0;
>  	return 0;
> diff --git a/drivers/net/team/team_mode_loadbalance.c b/drivers/net/team/team_mode_loadbalance.c
> index 45cc095..b4475a5 100644
> --- a/drivers/net/team/team_mode_loadbalance.c
> +++ b/drivers/net/team/team_mode_loadbalance.c
> @@ -96,7 +96,7 @@ static void lb_tx_hash_to_port_mapping_null_port(struct team *team,
>  		struct lb_port_mapping *pm;
>  
>  		pm = &lb_priv->ex->tx_hash_to_port_mapping[i];
> -		if (pm->port == port) {
> +		if (rcu_access_pointer(pm->port) == port) {

This one is OK

>  			rcu_assign_pointer(pm->port, NULL);

I dont understand why you submit two patches...

>  			team_option_inst_set_change(pm->opt_inst_info);
>  			changed = true;
> @@ -292,7 +292,7 @@ static int lb_bpf_func_set(struct team *team, struct team_gsetter_ctx *ctx)
>  	if (lb_priv->ex->orig_fprog) {
>  		/* Clear old filter data */
>  		__fprog_destroy(lb_priv->ex->orig_fprog);
> -		sk_unattached_filter_destroy(lb_priv->fp);
> +		sk_unattached_filter_destroy(rcu_access_pointer(lb_priv->fp));
>  	}


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Jiri Pirko June 20, 2012, 6:33 p.m. UTC | #2
Wed, Jun 20, 2012 at 06:01:44PM CEST, eric.dumazet@gmail.com wrote:
>On Wed, 2012-06-20 at 17:32 +0200, Jiri Pirko wrote:
>> Signed-off-by: Jiri Pirko <jpirko@redhat.com>
>> ---
>>  drivers/net/team/team_mode_activebackup.c |    7 +++++--
>>  drivers/net/team/team_mode_loadbalance.c  |    8 +++++---
>>  2 files changed, 10 insertions(+), 5 deletions(-)
>> 
>> diff --git a/drivers/net/team/team_mode_activebackup.c b/drivers/net/team/team_mode_activebackup.c
>> index 2fe02a8..c9e7621 100644
>> --- a/drivers/net/team/team_mode_activebackup.c
>> +++ b/drivers/net/team/team_mode_activebackup.c
>> @@ -61,8 +61,11 @@ static void ab_port_leave(struct team *team, struct team_port *port)
>>  
>>  static int ab_active_port_get(struct team *team, struct team_gsetter_ctx *ctx)
>>  {
>> -	if (ab_priv(team)->active_port)
>> -		ctx->data.u32_val = ab_priv(team)->active_port->dev->ifindex;
>> +	struct team_port *active_port;
>> +
>> +	active_port = rcu_access_pointer(ab_priv(team)->active_port);
>
>This is not the correct fix.
>
>You cant safely dereference active_port if you got it from
>rcu_access_pointer()

>
>You should use rcu_dereference() of rcu_dereference_protected() or
>rcu_dereference_bh() or similar variant, depending on the context.


Okay, reworking this using rcu_dereference_protected() since this is
update path.

>
>> +	if (active_port)
>> +		ctx->data.u32_val = active_port->dev->ifindex;
>>  	else
>>  		ctx->data.u32_val = 0;
>>  	return 0;
>> diff --git a/drivers/net/team/team_mode_loadbalance.c b/drivers/net/team/team_mode_loadbalance.c
>> index 45cc095..b4475a5 100644
>> --- a/drivers/net/team/team_mode_loadbalance.c
>> +++ b/drivers/net/team/team_mode_loadbalance.c
>> @@ -96,7 +96,7 @@ static void lb_tx_hash_to_port_mapping_null_port(struct team *team,
>>  		struct lb_port_mapping *pm;
>>  
>>  		pm = &lb_priv->ex->tx_hash_to_port_mapping[i];
>> -		if (pm->port == port) {
>> +		if (rcu_access_pointer(pm->port) == port) {
>
>This one is OK
>
>>  			rcu_assign_pointer(pm->port, NULL);
>
>I dont understand why you submit two patches...

Squashing into one now.

>
>>  			team_option_inst_set_change(pm->opt_inst_info);
>>  			changed = true;
>> @@ -292,7 +292,7 @@ static int lb_bpf_func_set(struct team *team, struct team_gsetter_ctx *ctx)
>>  	if (lb_priv->ex->orig_fprog) {
>>  		/* Clear old filter data */
>>  		__fprog_destroy(lb_priv->ex->orig_fprog);
>> -		sk_unattached_filter_destroy(lb_priv->fp);
>> +		sk_unattached_filter_destroy(rcu_access_pointer(lb_priv->fp));
>>  	}
>
>
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diff mbox

Patch

diff --git a/drivers/net/team/team_mode_activebackup.c b/drivers/net/team/team_mode_activebackup.c
index 2fe02a8..c9e7621 100644
--- a/drivers/net/team/team_mode_activebackup.c
+++ b/drivers/net/team/team_mode_activebackup.c
@@ -61,8 +61,11 @@  static void ab_port_leave(struct team *team, struct team_port *port)
 
 static int ab_active_port_get(struct team *team, struct team_gsetter_ctx *ctx)
 {
-	if (ab_priv(team)->active_port)
-		ctx->data.u32_val = ab_priv(team)->active_port->dev->ifindex;
+	struct team_port *active_port;
+
+	active_port = rcu_access_pointer(ab_priv(team)->active_port);
+	if (active_port)
+		ctx->data.u32_val = active_port->dev->ifindex;
 	else
 		ctx->data.u32_val = 0;
 	return 0;
diff --git a/drivers/net/team/team_mode_loadbalance.c b/drivers/net/team/team_mode_loadbalance.c
index 45cc095..b4475a5 100644
--- a/drivers/net/team/team_mode_loadbalance.c
+++ b/drivers/net/team/team_mode_loadbalance.c
@@ -96,7 +96,7 @@  static void lb_tx_hash_to_port_mapping_null_port(struct team *team,
 		struct lb_port_mapping *pm;
 
 		pm = &lb_priv->ex->tx_hash_to_port_mapping[i];
-		if (pm->port == port) {
+		if (rcu_access_pointer(pm->port) == port) {
 			rcu_assign_pointer(pm->port, NULL);
 			team_option_inst_set_change(pm->opt_inst_info);
 			changed = true;
@@ -292,7 +292,7 @@  static int lb_bpf_func_set(struct team *team, struct team_gsetter_ctx *ctx)
 	if (lb_priv->ex->orig_fprog) {
 		/* Clear old filter data */
 		__fprog_destroy(lb_priv->ex->orig_fprog);
-		sk_unattached_filter_destroy(lb_priv->fp);
+		sk_unattached_filter_destroy(rcu_access_pointer(lb_priv->fp));
 	}
 
 	rcu_assign_pointer(lb_priv->fp, fp);
@@ -303,9 +303,11 @@  static int lb_bpf_func_set(struct team *team, struct team_gsetter_ctx *ctx)
 static int lb_tx_method_get(struct team *team, struct team_gsetter_ctx *ctx)
 {
 	struct lb_priv *lb_priv = get_lb_priv(team);
+	lb_select_tx_port_func_t *func;
 	char *name;
 
-	name = lb_select_tx_port_get_name(lb_priv->select_tx_port_func);
+	func = rcu_access_pointer(lb_priv->select_tx_port_func);
+	name = lb_select_tx_port_get_name(func);
 	BUG_ON(!name);
 	ctx->data.str_val = name;
 	return 0;