diff mbox series

[net-next,v2,2/2] net: netpoll: flush skb pool during cleanup

Message ID 20241107-skb_buffers_v2-v2-2-288c6264ba4f@debian.org (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series net: netpoll: Improve SKB pool management | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 3 this patch: 3
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 6 of 6 maintainers
netdev/build_clang success Errors and warnings before: 3 this patch: 3
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 5 this patch: 5
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 43 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-11-11--21-00 (tests: 787)

Commit Message

Breno Leitao Nov. 7, 2024, 3:57 p.m. UTC
The netpoll subsystem maintains a pool of 32 pre-allocated SKBs per
instance, but these SKBs are not freed when the netpoll user is brought
down. This leads to memory waste as these buffers remain allocated but
unused.

Add skb_pool_flush() to properly clean up these SKBs when netconsole is
terminated, improving memory efficiency.

Signed-off-by: Breno Leitao <leitao@debian.org>
---
 net/core/netpoll.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

Comments

Jakub Kicinski Nov. 12, 2024, 12:57 a.m. UTC | #1
On Thu, 07 Nov 2024 07:57:07 -0800 Breno Leitao wrote:
> +static void skb_pool_flush(struct netpoll *np)
> +{
> +	struct sk_buff_head *skb_pool;
> +	struct sk_buff *skb;
> +	unsigned long flags;
> +
> +	skb_pool = &np->skb_pool;
> +
> +	spin_lock_irqsave(&skb_pool->lock, flags);
> +	while (skb_pool->qlen > 0) {
> +		skb = __skb_dequeue(skb_pool);
> +		kfree_skb(skb);
> +	}
> +	spin_unlock_irqrestore(&skb_pool->lock, flags);

 skb_queue_purge_reason(... SKB_CONSUMED)

should be able to replace the loop
diff mbox series

Patch

diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 719c9aae845fbeb6f5b53a2bef675d3cb8cd44a7..498cc38073a3dc9f829f74f254bc70b26ef3856c 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -531,6 +531,22 @@  static int netpoll_parse_ip_addr(const char *str, union inet_addr *addr)
 	return -1;
 }
 
+static void skb_pool_flush(struct netpoll *np)
+{
+	struct sk_buff_head *skb_pool;
+	struct sk_buff *skb;
+	unsigned long flags;
+
+	skb_pool = &np->skb_pool;
+
+	spin_lock_irqsave(&skb_pool->lock, flags);
+	while (skb_pool->qlen > 0) {
+		skb = __skb_dequeue(skb_pool);
+		kfree_skb(skb);
+	}
+	spin_unlock_irqrestore(&skb_pool->lock, flags);
+}
+
 int netpoll_parse_options(struct netpoll *np, char *opt)
 {
 	char *cur=opt, *delim;
@@ -779,10 +795,12 @@  int netpoll_setup(struct netpoll *np)
 
 	err = __netpoll_setup(np, ndev);
 	if (err)
-		goto put;
+		goto flush;
 	rtnl_unlock();
 	return 0;
 
+flush:
+	skb_pool_flush(np);
 put:
 	DEBUG_NET_WARN_ON_ONCE(np->dev);
 	if (ip_overwritten)
@@ -830,6 +848,8 @@  void __netpoll_cleanup(struct netpoll *np)
 		call_rcu(&npinfo->rcu, rcu_cleanup_netpoll_info);
 	} else
 		RCU_INIT_POINTER(np->dev->npinfo, NULL);
+
+	skb_pool_flush(np);
 }
 EXPORT_SYMBOL_GPL(__netpoll_cleanup);