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From: Adrian Moreno <amorenoz@redhat.com>
To: netdev@vger.kernel.org
Cc: aconole@redhat.com,
	echaudro@redhat.com,
	horms@kernel.org,
	i.maximets@ovn.org,
	dev@openvswitch.org,
	Adrian Moreno <amorenoz@redhat.com>,
	Yotam Gigi <yotam.gi@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>,
	Paolo Abeni <pabeni@redhat.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH net-next v2 3/9] net: psample: skip packet copy if no listeners
Date: Mon,  3 Jun 2024 20:56:37 +0200
Message-ID: <20240603185647.2310748-4-amorenoz@redhat.com>
In-Reply-To: <20240603185647.2310748-1-amorenoz@redhat.com>
References: <20240603185647.2310748-1-amorenoz@redhat.com>
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If nobody is listening on the multicast group, generating the sample,
which involves copying packet data, seems completely unnecessary.

Return fast in this case.

Signed-off-by: Adrian Moreno <amorenoz@redhat.com>
---
 net/psample/psample.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/psample/psample.c b/net/psample/psample.c
index b37488f426bc..1c76f3e48dcd 100644
--- a/net/psample/psample.c
+++ b/net/psample/psample.c
@@ -376,6 +376,10 @@ void psample_sample_packet(struct psample_group *group, struct sk_buff *skb,
 	void *data;
 	int ret;
 
+	if (!genl_has_listeners(&psample_nl_family, group->net,
+				PSAMPLE_NL_MCGRP_SAMPLE))
+		return;
+
 	meta_len = (in_ifindex ? nla_total_size(sizeof(u16)) : 0) +
 		   (out_ifindex ? nla_total_size(sizeof(u16)) : 0) +
 		   (md->out_tc_valid ? nla_total_size(sizeof(u16)) : 0) +
-- 
2.45.1