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bridge: fix regression in ageing time

PATCH In review Stephen Hemminger 3 participants 4 messages Feb 12, 2016 – Feb 15, 2016

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Networking Network drivers Ethernet bridge
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Stephen Hemminger

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#0 lore raw

PATCH 1/1 bridge: fix regression in ageing time

This fixes a regression in the bridge ageing time caused by:

commit c62987bbd8a1 ("bridge: push bridge setting ageing_time down to switchdev")

There are users of Linux bridge which use the feature that if ageing time is set to 0 it causes entries to never expire.
This feature is even listed on the web page:
https://www.linuxfoundation.org/collaborate/workgroups/networking/bridge

For a pure software bridge, it is unnecessary for the code to have arbitrary restrictions on what values are allowable.

Signed-off-by Stephen Hemminger <[email protected]>

---
Please apply to 4.4 for stable as well.

 include/linux/if_bridge.h |    5 -----
 net/bridge/br_stp.c       |    9 ++++++---
 2 files changed, 6 insertions(+), 8 deletions(-)
include/linux/if_bridge.h +0 -5
@@ -45,11 +45,6 @@ struct br_ip_list {
 #define BR_PROXYARP		BIT(8)
 #define BR_LEARNING_SYNC	BIT(9)
 #define BR_PROXYARP_WIFI	BIT(10)
-
-/* values as per ieee8021QBridgeFdbAgingTime */
-#define BR_MIN_AGEING_TIME	(10 * HZ)
-#define BR_MAX_AGEING_TIME	(1000000 * HZ)
-
 #define BR_DEFAULT_AGEING_TIME	(300 * HZ)
 
 extern void brioctl_set(int (*ioctl_hook)(struct net *, unsigned int, void __user *));
net/bridge/br_stp.c +6 -3
@@ -568,6 +568,12 @@ int br_set_max_age(struct net_bridge *br
 
 }
 
+/* Set the how long dynamic forwarding database entries live.
+ * The Linux bridge allows values outside the standard 802.1
+ * specification to allow for special cases:
+ *   0 - means entry never age.
+ *   1 - means entries disappear in next clock tick
+ */
 int br_set_ageing_time(struct net_bridge *br, u32 ageing_time)
 {
 	struct switchdev_attr attr = {

@@ -579,9 +585,6 @@ int br_set_ageing_time(struct net_bridge
 	unsigned long t = clock_t_to_jiffies(ageing_time);
 	int err;
 
-	if (t < BR_MIN_AGEING_TIME || t > BR_MAX_AGEING_TIME)
-		return -ERANGE;
-
 	err = switchdev_port_attr_set(br->dev, &attr);
 	if (err)
 		return err;
#1 lore raw

Fri, Feb 12, 2016 at 11:31:09PM IST, [email protected] wrote:

Hi,

Quoted 24 lines

This fixes a regression in the bridge ageing time caused by:

commit c62987bbd8a1 ("bridge: push bridge setting ageing_time down to switchdev")

There are users of Linux bridge which use the feature that if ageing time is set to 0 it causes entries to never expire.
This feature is even listed on the web page:
https://www.linuxfoundation.org/collaborate/workgroups/networking/bridge

For a pure software bridge, it is unnecessary for the code to have arbitrary restrictions on what values are allowable.

Signed-off-by Stephen Hemminger <[email protected]>

---
Please apply to 4.4 for stable as well.

include/linux/if_bridge.h |    5 -----
net/bridge/br_stp.c       |    9 ++++++---
2 files changed, 6 insertions(+), 8 deletions(-)

include/linux/if_bridge.h struct br_ip_list { · line 50

Quoted 6 lines
include/linux/if_bridge.h +0 -3
@@ -45,11 +45,6 @@ struct br_ip_list {
 #define BR_PROXYARP		BIT(8)
 #define BR_LEARNING_SYNC	BIT(9)
 #define BR_PROXYARP_WIFI	BIT(10)
-
-/* values as per ieee8021QBridgeFdbAgingTime */
-#define BR_MIN_AGEING_TIME	(10 * HZ)

rocker is using this value:

vi drivers/net/ethernet/rocker/rocker.c +3707

net/bridge/br_stp.c int br_set_max_age(struct net_bridge *br · line 571

Quoted 12 lines
include/linux/if_bridge.h +0 -2
-#define BR_MAX_AGEING_TIME	(1000000 * HZ)
-
 #define BR_DEFAULT_AGEING_TIME	(300 * HZ)
 
 extern void brioctl_set(int (*ioctl_hook)(struct net *, unsigned int, void __user *));
net/bridge/br_stp.c +1 -0
@@ -568,6 +568,12 @@ int br_set_max_age(struct net_bridge *br
 
 }
 
+/* Set the how long dynamic forwarding database entries live.

Maybe drop the 'the'?

net/bridge/br_stp.c int br_set_max_age(struct net_bridge *br · line 574

Quoted 3 lines
net/bridge/br_stp.c +3 -0
+ * The Linux bridge allows values outside the standard 802.1
+ * specification to allow for special cases:
+ *   0 - means entry never age.

s/entry/entries/ ?

net/bridge/br_stp.c int br_set_max_age(struct net_bridge *br · line 575

Quoted 1 line
net/bridge/br_stp.c +1 -0
+ *   1 - means entries disappear in next clock tick

Missing dot. ;)

net/bridge/br_stp.c int br_set_ageing_time(struct net_bridge · line 583

Quoted 10 lines
net/bridge/br_stp.c +1 -2
+ */
 int br_set_ageing_time(struct net_bridge *br, u32 ageing_time)
 {
 	struct switchdev_attr attr = {

@@ -579,9 +585,6 @@ int br_set_ageing_time(struct net_bridge
 	unsigned long t = clock_t_to_jiffies(ageing_time);
 	int err;
 
-	if (t < BR_MIN_AGEING_TIME || t > BR_MAX_AGEING_TIME)
-		return -ERANGE;

Removing this and trying to set ageing time to 0 will cause mlxsw driver to error out (firmware is checking for min value). I will send you a patch for both rocker and mlxsw tomorrow, so that you can squash to yours and do this change atomically.

Thanks for looking into this.

Quoted 4 lines
net/bridge/br_stp.c +0 -1
-
 	err = switchdev_port_attr_set(br->dev, &attr);
 	if (err)
 		return err;
#2 lore raw
In reply to Stephen Hemminger
Quoted 38 lines · Fri, Feb 12, 2016 at 11:31:09PM IST, [email protected] wrote:

This fixes a regression in the bridge ageing time caused by:

commit c62987bbd8a1 ("bridge: push bridge setting ageing_time down to switchdev")

There are users of Linux bridge which use the feature that if ageing time is set to 0 it causes entries to never expire.
This feature is even listed on the web page:
https://www.linuxfoundation.org/collaborate/workgroups/networking/bridge

For a pure software bridge, it is unnecessary for the code to have arbitrary restrictions on what values are allowable.

Signed-off-by Stephen Hemminger <[email protected]>

---
Please apply to 4.4 for stable as well.

include/linux/if_bridge.h |    5 -----
net/bridge/br_stp.c       |    9 ++++++---
2 files changed, 6 insertions(+), 8 deletions(-)
include/linux/if_bridge.h +0 -5
@@ -45,11 +45,6 @@ struct br_ip_list {
 #define BR_PROXYARP		BIT(8)
 #define BR_LEARNING_SYNC	BIT(9)
 #define BR_PROXYARP_WIFI	BIT(10)
-
-/* values as per ieee8021QBridgeFdbAgingTime */
-#define BR_MIN_AGEING_TIME	(10 * HZ)
-#define BR_MAX_AGEING_TIME	(1000000 * HZ)
-
 #define BR_DEFAULT_AGEING_TIME	(300 * HZ)
 
 extern void brioctl_set(int (*ioctl_hook)(struct net *, unsigned int, void __user *));

net/bridge/br_stp.c int br_set_max_age(struct net_bridge *br · line 574

Quoted 7 lines
net/bridge/br_stp.c +4 -0
@@ -568,6 +568,12 @@ int br_set_max_age(struct net_bridge *br
 
 }
 
+/* Set the how long dynamic forwarding database entries live.
+ * The Linux bridge allows values outside the standard 802.1
+ * specification to allow for special cases:
+ *   0 - means entry never age.

Looking at the code I didn't quite understand how this could happen and indeed with your patch I see that the FDB is never populated. Maybe that's the expected behavior? I also found the following, which seems to support this:

https://lists.linuxfoundation.org/pipermail/bridge/2010-November/007410.html

Thanks.

Quoted 15 lines
net/bridge/br_stp.c +2 -3
+ *   1 - means entries disappear in next clock tick
+ */
 int br_set_ageing_time(struct net_bridge *br, u32 ageing_time)
 {
 	struct switchdev_attr attr = {

@@ -579,9 +585,6 @@ int br_set_ageing_time(struct net_bridge
 	unsigned long t = clock_t_to_jiffies(ageing_time);
 	int err;
 
-	if (t < BR_MIN_AGEING_TIME || t > BR_MAX_AGEING_TIME)
-		return -ERANGE;
-
 	err = switchdev_port_attr_set(br->dev, &attr);
 	if (err)
 		return err;
#3 lore raw
In reply to Stephen Hemminger
Quoted 51 lines · Fri, Feb 12, 2016 at 10:31:09PM CET, [email protected] wrote:

This fixes a regression in the bridge ageing time caused by:

commit c62987bbd8a1 ("bridge: push bridge setting ageing_time down to switchdev")

There are users of Linux bridge which use the feature that if ageing time is set to 0 it causes entries to never expire.
This feature is even listed on the web page:
https://www.linuxfoundation.org/collaborate/workgroups/networking/bridge

For a pure software bridge, it is unnecessary for the code to have arbitrary restrictions on what values are allowable.

Signed-off-by Stephen Hemminger <[email protected]>

---
Please apply to 4.4 for stable as well.

include/linux/if_bridge.h |    5 -----
net/bridge/br_stp.c       |    9 ++++++---
2 files changed, 6 insertions(+), 8 deletions(-)
include/linux/if_bridge.h +0 -5
@@ -45,11 +45,6 @@ struct br_ip_list {
 #define BR_PROXYARP		BIT(8)
 #define BR_LEARNING_SYNC	BIT(9)
 #define BR_PROXYARP_WIFI	BIT(10)
-
-/* values as per ieee8021QBridgeFdbAgingTime */
-#define BR_MIN_AGEING_TIME	(10 * HZ)
-#define BR_MAX_AGEING_TIME	(1000000 * HZ)
-
 #define BR_DEFAULT_AGEING_TIME	(300 * HZ)
 
 extern void brioctl_set(int (*ioctl_hook)(struct net *, unsigned int, void __user *));
net/bridge/br_stp.c +6 -0
@@ -568,6 +568,12 @@ int br_set_max_age(struct net_bridge *br
 
 }
 
+/* Set the how long dynamic forwarding database entries live.
+ * The Linux bridge allows values outside the standard 802.1
+ * specification to allow for special cases:
+ *   0 - means entry never age.
+ *   1 - means entries disappear in next clock tick
+ */
 int br_set_ageing_time(struct net_bridge *br, u32 ageing_time)
 {
 	struct switchdev_attr attr = {

net/bridge/br_stp.c int br_set_ageing_time(struct net_bridge · line 584

Quoted 6 lines
net/bridge/br_stp.c +0 -3
@@ -579,9 +585,6 @@ int br_set_ageing_time(struct net_bridge
 	unsigned long t = clock_t_to_jiffies(ageing_time);
 	int err;
 
-	if (t < BR_MIN_AGEING_TIME || t > BR_MAX_AGEING_TIME)
-		return -ERANGE;
-

rocker and mlxsw rely on this check. If you remove it here, you have to add it there.

Quoted 3 lines
net/bridge/br_stp.c +0 -0
 	err = switchdev_port_attr_set(br->dev, &attr);
 	if (err)
 		return err;