[PATCH net-next] net: loopback: Do not allocate tstats explicitly

[PATCH net-next] net: loopback: Do not allocate tstats explicitly

[Breno Leitao]

With commit 34d21de99cea9 ("net: Move {l,t,d}stats allocation to core and
convert veth & vrf"), stats allocation could be done on net core
instead of in this driver.

With this new approach, the driver doesn't have to bother with error
handling (allocation failure checking, making sure free happens in the
right spot, etc). This is core responsibility now.

Remove the allocation in the loopback driver and leverage the network
core allocation instead.

Signed-off-by: Breno Leitao <leitao@debian.org>
---
 drivers/net/loopback.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c
index f6eab66c2660..2b486e7c749c 100644
--- a/drivers/net/loopback.c
+++ b/drivers/net/loopback.c
@@ -141,9 +141,6 @@ static const struct ethtool_ops loopback_ethtool_ops = {
 
 static int loopback_dev_init(struct net_device *dev)
 {
-	dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
-	if (!dev->lstats)
-		return -ENOMEM;
 	netdev_lockdep_set_classes(dev);
 	return 0;
 }
@@ -151,7 +148,6 @@ static int loopback_dev_init(struct net_device *dev)
 static void loopback_dev_free(struct net_device *dev)
 {
 	dev_net(dev)->loopback_dev = NULL;
-	free_percpu(dev->lstats);
 }
 
 static const struct net_device_ops loopback_ops = {
@@ -191,6 +187,7 @@ static void gen_lo_setup(struct net_device *dev,
 	dev->header_ops		= hdr_ops;
 	dev->netdev_ops		= dev_ops;
 	dev->needs_free_netdev	= true;
+	dev->pcpu_stat_type	= NETDEV_PCPU_STAT_LSTATS;
 	dev->priv_destructor	= dev_destructor;
 
 	netif_set_tso_max_size(dev, GSO_MAX_SIZE);
-- 
2.43.0

Re: [PATCH net-next] net: loopback: Do not allocate tstats explicitly

[Sabrina Dubroca]

(nit on the subject: you mention "tstats", but the code actually uses
lstats. I guess that's not worth a v2)

2024-04-29, 01:55:58 -0700, Breno Leitao wrote:
> With commit 34d21de99cea9 ("net: Move {l,t,d}stats allocation to core and
> convert veth & vrf"), stats allocation could be done on net core
> instead of in this driver.
> 
> With this new approach, the driver doesn't have to bother with error
> handling (allocation failure checking, making sure free happens in the
> right spot, etc). This is core responsibility now.
> 
> Remove the allocation in the loopback driver and leverage the network
> core allocation instead.
> 
> Signed-off-by: Breno Leitao <leitao@debian.org>

Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>

-- 
Sabrina

Re: [PATCH net-next] net: loopback: Do not allocate tstats explicitly

[Jakub Kicinski]

On Mon, 29 Apr 2024 15:47:05 +0200 Sabrina Dubroca wrote:
> (nit on the subject: you mention "tstats", but the code actually uses
> lstats. I guess that's not worth a v2)

Good catch, corrected when applying - 3b5933e99c32 ("net: loopback: Do
not allocate lstats explicitly") in net-next.
-- 
pw-bot: accept