* [PATCH] net: bridge: Slightly optimize br_stp_change_bridge_id()
@ 2022-02-12 9:58 ` Christophe JAILLET
0 siblings, 0 replies; 4+ messages in thread
From: Christophe JAILLET @ 2022-02-12 9:58 UTC (permalink / raw)
To: Roopa Prabhu, Nikolay Aleksandrov, David S. Miller, Jakub Kicinski
Cc: linux-kernel, kernel-janitors, Christophe JAILLET, bridge, netdev
ether_addr_equal_64bits() can easy be used in place of ether_addr_equal()
here.
Padding in the 'net_bridge_port' structure is already there because it is a
huge structure and the required fields are not at the end.
'oldaddr' is local to the function. So add the required padding
explicitly and simplify its definition.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
This patch is more a POC for me.
I'm unsure that using ether_addr_equal_64bits() is really useful. The
speedup should be mostly un-noticeable.
To make sure that we have the required padding, we either need to waste
some space or rely on the fact that the address is embedded in a large
enough structure. (which is the case here)
So, it looks fragile to me and not future-proof.
Feed-back highly appreciated to see if such patches are welcome and if I
should spend some time on it.
---
net/bridge/br_private.h | 5 +++++
net/bridge/br_stp_if.c | 12 +++++++-----
2 files changed, 12 insertions(+), 5 deletions(-)
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 2661dda1a92b..2f78090574c9 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -363,6 +363,11 @@ struct net_bridge_port {
unsigned char config_pending;
port_id port_id;
port_id designated_port;
+ /*
+ * designated_root and designated_bridge must NOT be at the end of the
+ * structure because ether_addr_equal_64bits() requires 2 bytes of
+ * padding.
+ */
bridge_id designated_root;
bridge_id designated_bridge;
u32 path_cost;
diff --git a/net/bridge/br_stp_if.c b/net/bridge/br_stp_if.c
index 75204d36d7f9..1bf0aaf29e5e 100644
--- a/net/bridge/br_stp_if.c
+++ b/net/bridge/br_stp_if.c
@@ -221,9 +221,11 @@ int br_stp_set_enabled(struct net_bridge *br, unsigned long val,
/* called under bridge lock */
void br_stp_change_bridge_id(struct net_bridge *br, const unsigned char *addr)
{
- /* should be aligned on 2 bytes for ether_addr_equal() */
- unsigned short oldaddr_aligned[ETH_ALEN >> 1];
- unsigned char *oldaddr = (unsigned char *)oldaddr_aligned;
+ /*
+ * should be aligned on 2 bytes and have 2 bytes of padding for
+ * ether_addr_equal_64bits()
+ */
+ unsigned char oldaddr[ETH_ALEN + 2] __aligned(2);
struct net_bridge_port *p;
int wasroot;
@@ -236,10 +238,10 @@ void br_stp_change_bridge_id(struct net_bridge *br, const unsigned char *addr)
eth_hw_addr_set(br->dev, addr);
list_for_each_entry(p, &br->port_list, list) {
- if (ether_addr_equal(p->designated_bridge.addr, oldaddr))
+ if (ether_addr_equal_64bits(p->designated_bridge.addr, oldaddr))
memcpy(p->designated_bridge.addr, addr, ETH_ALEN);
- if (ether_addr_equal(p->designated_root.addr, oldaddr))
+ if (ether_addr_equal_64bits(p->designated_root.addr, oldaddr))
memcpy(p->designated_root.addr, addr, ETH_ALEN);
}
--
2.32.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [Bridge] [PATCH] net: bridge: Slightly optimize br_stp_change_bridge_id()
@ 2022-02-12 9:58 ` Christophe JAILLET
0 siblings, 0 replies; 4+ messages in thread
From: Christophe JAILLET @ 2022-02-12 9:58 UTC (permalink / raw)
To: Roopa Prabhu, Nikolay Aleksandrov, David S. Miller, Jakub Kicinski
Cc: Christophe JAILLET, bridge, kernel-janitors, linux-kernel, netdev
ether_addr_equal_64bits() can easy be used in place of ether_addr_equal()
here.
Padding in the 'net_bridge_port' structure is already there because it is a
huge structure and the required fields are not at the end.
'oldaddr' is local to the function. So add the required padding
explicitly and simplify its definition.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
This patch is more a POC for me.
I'm unsure that using ether_addr_equal_64bits() is really useful. The
speedup should be mostly un-noticeable.
To make sure that we have the required padding, we either need to waste
some space or rely on the fact that the address is embedded in a large
enough structure. (which is the case here)
So, it looks fragile to me and not future-proof.
Feed-back highly appreciated to see if such patches are welcome and if I
should spend some time on it.
---
net/bridge/br_private.h | 5 +++++
net/bridge/br_stp_if.c | 12 +++++++-----
2 files changed, 12 insertions(+), 5 deletions(-)
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 2661dda1a92b..2f78090574c9 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -363,6 +363,11 @@ struct net_bridge_port {
unsigned char config_pending;
port_id port_id;
port_id designated_port;
+ /*
+ * designated_root and designated_bridge must NOT be at the end of the
+ * structure because ether_addr_equal_64bits() requires 2 bytes of
+ * padding.
+ */
bridge_id designated_root;
bridge_id designated_bridge;
u32 path_cost;
diff --git a/net/bridge/br_stp_if.c b/net/bridge/br_stp_if.c
index 75204d36d7f9..1bf0aaf29e5e 100644
--- a/net/bridge/br_stp_if.c
+++ b/net/bridge/br_stp_if.c
@@ -221,9 +221,11 @@ int br_stp_set_enabled(struct net_bridge *br, unsigned long val,
/* called under bridge lock */
void br_stp_change_bridge_id(struct net_bridge *br, const unsigned char *addr)
{
- /* should be aligned on 2 bytes for ether_addr_equal() */
- unsigned short oldaddr_aligned[ETH_ALEN >> 1];
- unsigned char *oldaddr = (unsigned char *)oldaddr_aligned;
+ /*
+ * should be aligned on 2 bytes and have 2 bytes of padding for
+ * ether_addr_equal_64bits()
+ */
+ unsigned char oldaddr[ETH_ALEN + 2] __aligned(2);
struct net_bridge_port *p;
int wasroot;
@@ -236,10 +238,10 @@ void br_stp_change_bridge_id(struct net_bridge *br, const unsigned char *addr)
eth_hw_addr_set(br->dev, addr);
list_for_each_entry(p, &br->port_list, list) {
- if (ether_addr_equal(p->designated_bridge.addr, oldaddr))
+ if (ether_addr_equal_64bits(p->designated_bridge.addr, oldaddr))
memcpy(p->designated_bridge.addr, addr, ETH_ALEN);
- if (ether_addr_equal(p->designated_root.addr, oldaddr))
+ if (ether_addr_equal_64bits(p->designated_root.addr, oldaddr))
memcpy(p->designated_root.addr, addr, ETH_ALEN);
}
--
2.32.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] net: bridge: Slightly optimize br_stp_change_bridge_id()
2022-02-12 9:58 ` [Bridge] " Christophe JAILLET
@ 2022-02-13 10:13 ` Nikolay Aleksandrov
-1 siblings, 0 replies; 4+ messages in thread
From: Nikolay Aleksandrov @ 2022-02-13 10:13 UTC (permalink / raw)
To: Christophe JAILLET, Roopa Prabhu, David S. Miller, Jakub Kicinski
Cc: linux-kernel, kernel-janitors, bridge, netdev
On 12/02/2022 11:58, Christophe JAILLET wrote:
> ether_addr_equal_64bits() can easy be used in place of ether_addr_equal()
> here.
> Padding in the 'net_bridge_port' structure is already there because it is a
> huge structure and the required fields are not at the end.
> 'oldaddr' is local to the function. So add the required padding
> explicitly and simplify its definition.
>
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> ---
> This patch is more a POC for me.
>
> I'm unsure that using ether_addr_equal_64bits() is really useful. The
> speedup should be mostly un-noticeable.
>
> To make sure that we have the required padding, we either need to waste
> some space or rely on the fact that the address is embedded in a large
> enough structure. (which is the case here)
>
> So, it looks fragile to me and not future-proof.
>
> Feed-back highly appreciated to see if such patches are welcome and if I
> should spend some time on it.
> ---
This is slow path, more so as you've noted above the change is fragile and someone
can easily miss it, I appreciate the comments but for this case I'd prefer to
leave the code as-is to keep it obviously correct and avoid future problems.
Thanks,
Nik
> net/bridge/br_private.h | 5 +++++
> net/bridge/br_stp_if.c | 12 +++++++-----
> 2 files changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
> index 2661dda1a92b..2f78090574c9 100644
> --- a/net/bridge/br_private.h
> +++ b/net/bridge/br_private.h
> @@ -363,6 +363,11 @@ struct net_bridge_port {
> unsigned char config_pending;
> port_id port_id;
> port_id designated_port;
> + /*
> + * designated_root and designated_bridge must NOT be at the end of the
> + * structure because ether_addr_equal_64bits() requires 2 bytes of
> + * padding.
> + */
> bridge_id designated_root;
> bridge_id designated_bridge;
> u32 path_cost;
> diff --git a/net/bridge/br_stp_if.c b/net/bridge/br_stp_if.c
> index 75204d36d7f9..1bf0aaf29e5e 100644
> --- a/net/bridge/br_stp_if.c
> +++ b/net/bridge/br_stp_if.c
> @@ -221,9 +221,11 @@ int br_stp_set_enabled(struct net_bridge *br, unsigned long val,
> /* called under bridge lock */
> void br_stp_change_bridge_id(struct net_bridge *br, const unsigned char *addr)
> {
> - /* should be aligned on 2 bytes for ether_addr_equal() */
> - unsigned short oldaddr_aligned[ETH_ALEN >> 1];
> - unsigned char *oldaddr = (unsigned char *)oldaddr_aligned;
> + /*
> + * should be aligned on 2 bytes and have 2 bytes of padding for
> + * ether_addr_equal_64bits()
> + */
> + unsigned char oldaddr[ETH_ALEN + 2] __aligned(2);
> struct net_bridge_port *p;
> int wasroot;
>
> @@ -236,10 +238,10 @@ void br_stp_change_bridge_id(struct net_bridge *br, const unsigned char *addr)
> eth_hw_addr_set(br->dev, addr);
>
> list_for_each_entry(p, &br->port_list, list) {
> - if (ether_addr_equal(p->designated_bridge.addr, oldaddr))
> + if (ether_addr_equal_64bits(p->designated_bridge.addr, oldaddr))
> memcpy(p->designated_bridge.addr, addr, ETH_ALEN);
>
> - if (ether_addr_equal(p->designated_root.addr, oldaddr))
> + if (ether_addr_equal_64bits(p->designated_root.addr, oldaddr))
> memcpy(p->designated_root.addr, addr, ETH_ALEN);
> }
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Bridge] [PATCH] net: bridge: Slightly optimize br_stp_change_bridge_id()
@ 2022-02-13 10:13 ` Nikolay Aleksandrov
0 siblings, 0 replies; 4+ messages in thread
From: Nikolay Aleksandrov @ 2022-02-13 10:13 UTC (permalink / raw)
To: Christophe JAILLET, Roopa Prabhu, David S. Miller, Jakub Kicinski
Cc: netdev, bridge, kernel-janitors, linux-kernel
On 12/02/2022 11:58, Christophe JAILLET wrote:
> ether_addr_equal_64bits() can easy be used in place of ether_addr_equal()
> here.
> Padding in the 'net_bridge_port' structure is already there because it is a
> huge structure and the required fields are not at the end.
> 'oldaddr' is local to the function. So add the required padding
> explicitly and simplify its definition.
>
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> ---
> This patch is more a POC for me.
>
> I'm unsure that using ether_addr_equal_64bits() is really useful. The
> speedup should be mostly un-noticeable.
>
> To make sure that we have the required padding, we either need to waste
> some space or rely on the fact that the address is embedded in a large
> enough structure. (which is the case here)
>
> So, it looks fragile to me and not future-proof.
>
> Feed-back highly appreciated to see if such patches are welcome and if I
> should spend some time on it.
> ---
This is slow path, more so as you've noted above the change is fragile and someone
can easily miss it, I appreciate the comments but for this case I'd prefer to
leave the code as-is to keep it obviously correct and avoid future problems.
Thanks,
Nik
> net/bridge/br_private.h | 5 +++++
> net/bridge/br_stp_if.c | 12 +++++++-----
> 2 files changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
> index 2661dda1a92b..2f78090574c9 100644
> --- a/net/bridge/br_private.h
> +++ b/net/bridge/br_private.h
> @@ -363,6 +363,11 @@ struct net_bridge_port {
> unsigned char config_pending;
> port_id port_id;
> port_id designated_port;
> + /*
> + * designated_root and designated_bridge must NOT be at the end of the
> + * structure because ether_addr_equal_64bits() requires 2 bytes of
> + * padding.
> + */
> bridge_id designated_root;
> bridge_id designated_bridge;
> u32 path_cost;
> diff --git a/net/bridge/br_stp_if.c b/net/bridge/br_stp_if.c
> index 75204d36d7f9..1bf0aaf29e5e 100644
> --- a/net/bridge/br_stp_if.c
> +++ b/net/bridge/br_stp_if.c
> @@ -221,9 +221,11 @@ int br_stp_set_enabled(struct net_bridge *br, unsigned long val,
> /* called under bridge lock */
> void br_stp_change_bridge_id(struct net_bridge *br, const unsigned char *addr)
> {
> - /* should be aligned on 2 bytes for ether_addr_equal() */
> - unsigned short oldaddr_aligned[ETH_ALEN >> 1];
> - unsigned char *oldaddr = (unsigned char *)oldaddr_aligned;
> + /*
> + * should be aligned on 2 bytes and have 2 bytes of padding for
> + * ether_addr_equal_64bits()
> + */
> + unsigned char oldaddr[ETH_ALEN + 2] __aligned(2);
> struct net_bridge_port *p;
> int wasroot;
>
> @@ -236,10 +238,10 @@ void br_stp_change_bridge_id(struct net_bridge *br, const unsigned char *addr)
> eth_hw_addr_set(br->dev, addr);
>
> list_for_each_entry(p, &br->port_list, list) {
> - if (ether_addr_equal(p->designated_bridge.addr, oldaddr))
> + if (ether_addr_equal_64bits(p->designated_bridge.addr, oldaddr))
> memcpy(p->designated_bridge.addr, addr, ETH_ALEN);
>
> - if (ether_addr_equal(p->designated_root.addr, oldaddr))
> + if (ether_addr_equal_64bits(p->designated_root.addr, oldaddr))
> memcpy(p->designated_root.addr, addr, ETH_ALEN);
> }
>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-02-13 10:13 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2022-02-12 9:58 [PATCH] net: bridge: Slightly optimize br_stp_change_bridge_id() Christophe JAILLET
2022-02-12 9:58 ` [Bridge] " Christophe JAILLET
2022-02-13 10:13 ` Nikolay Aleksandrov
2022-02-13 10:13 ` [Bridge] " Nikolay Aleksandrov
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