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netconsole: move find_skb() from netpoll

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find_skb() is the netconsole-specific entry into the netpoll skb
pool: every other netpoll consumer (bonding, team, vlan, bridge,
macvlan, dsa) builds its own sk_buff and never touches the pool.
With netpoll_send_udp() (its only caller) now living in netconsole,
find_skb() can join it.

Move find_skb() into drivers/net/netconsole.c as a file-static
helper, drop EXPORT_SYMBOL_GPL(find_skb) and remove its prototype
from include/linux/netpoll.h. find_skb() drains TX completions via
netpoll_zap_completion_queue(), which is already exported in the
NETDEV_INTERNAL namespace, so netconsole picks up
MODULE_IMPORT_NS("NETDEV_INTERNAL") to consume it.

The skb pool's lifecycle (np->skb_pool, np->refill_wq, refill_skbs(),
refill_skbs_work_handler(), skb_pool_flush()) stays in netpoll: it
is initialised in __netpoll_setup() and torn down in
__netpoll_cleanup(), both of which remain netpoll's responsibility.
The refill work queued via schedule_work(&np->refill_wq) from the
moved find_skb() runs refill_skbs_work_handler() in netpoll without
any further plumbing.

This is pure code motion: the function body is unchanged and its
sole caller (netpoll_send_udp(), already moved by an earlier patch)
keeps invoking it the same way. Pre-existing concerns about
find_skb() running from NMI/printk context (zap_completion_queue()
re-entry, skb_pool spinlocks, GFP_ATOMIC allocation, fallback skb
sizing vs. MAX_SKB_SIZE, PREEMPT_RT semantics of __kfree_skb()) are
inherited as-is and are not addressed here; they predate this
series and are out of scope. Fixing them is left for follow-up
work.

Signed-off-by: Breno Leitao <leitao@debian.org>
Link: https://patch.msgid.link/20260512-netconsole_split-v2-9-1191d14ad66d@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Breno Leitao 2026-05-12 03:46:42 -07:00 committed by Jakub Kicinski
parent 7bb1daff36
commit f35422ed36
3 changed files with 28 additions and 29 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
drivers/net/netconsole.c
View File

@ -50,6 +50,7 @@
MODULE_AUTHOR("Matt Mackall <mpm@selenic.com>");
MODULE_DESCRIPTION("Console driver for network interfaces");
MODULE_LICENSE("GPL");
MODULE_IMPORT_NS("NETDEV_INTERNAL");
#define MAX_PARAM_LENGTH 256
#define MAX_EXTRADATA_ENTRY_LEN 256
@ -1653,6 +1654,33 @@ static struct notifier_block netconsole_netdev_notifier = {
.notifier_call = netconsole_netdev_event,
};
static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
{
int count = 0;
struct sk_buff *skb;
netpoll_zap_completion_queue();
repeat:
skb = alloc_skb(len, GFP_ATOMIC);
if (!skb) {
skb = skb_dequeue(&np->skb_pool);
schedule_work(&np->refill_wq);
}
if (!skb) {
if (++count < 10) {
netpoll_poll_dev(np->dev);
goto repeat;
}
return NULL;
}
refcount_set(&skb->users, 1);
skb_reserve(skb, reserve);
return skb;
}
static void netpoll_udp_checksum(struct netpoll *np, struct sk_buff *skb,
int len)
{

1
include/linux/netpoll.h
View File

@ -73,7 +73,6 @@ void __netpoll_free(struct netpoll *np);
void netpoll_cleanup(struct netpoll *np);
void do_netpoll_cleanup(struct netpoll *np);
netdev_tx_t netpoll_send_skb(struct netpoll *np, struct sk_buff *skb);
struct sk_buff *find_skb(struct netpoll *np, int len, int reserve);
void netpoll_zap_completion_queue(void);
#ifdef CONFIG_NETPOLL

28
net/core/netpoll.c
View File

@ -265,34 +265,6 @@ void netpoll_zap_completion_queue(void)
}
EXPORT_SYMBOL_NS_GPL(netpoll_zap_completion_queue, "NETDEV_INTERNAL");
struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
{
int count = 0;
struct sk_buff *skb;
netpoll_zap_completion_queue();
repeat:
skb = alloc_skb(len, GFP_ATOMIC);
if (!skb) {
skb = skb_dequeue(&np->skb_pool);
schedule_work(&np->refill_wq);
}
if (!skb) {
if (++count < 10) {
netpoll_poll_dev(np->dev);
goto repeat;
}
return NULL;
}
refcount_set(&skb->users, 1);
skb_reserve(skb, reserve);
return skb;
}
EXPORT_SYMBOL_GPL(find_skb);
static int netpoll_owner_active(struct net_device *dev)
{
struct napi_struct *napi;