netdev - [PATCH 3/3] [RFC] Bluetooth: enable bpf TX timestamping

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Message-ID: <bbd7fa454ed03ebba9bfe79590fb78a75d4f07db.1743337403.git.pav@iki.fi>
Date: Sun, 30 Mar 2025 15:23:38 +0300
From: Pauli Virtanen <pav@....fi>
To: linux-bluetooth@...r.kernel.org
Cc: Pauli Virtanen <pav@....fi>,
	netdev@...r.kernel.org,
	bpf@...r.kernel.org,
	willemdebruijn.kernel@...il.com,
	kerneljasonxing@...il.com
Subject: [PATCH 3/3] [RFC] Bluetooth: enable bpf TX timestamping

Emit timestamps also for BPF timestamping.

***

The tskey management here is not quite right: see cover letter.
---
 include/net/bluetooth/bluetooth.h |  1 +
 net/bluetooth/hci_conn.c          | 21 +++++++++++++++++++--
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/include/net/bluetooth/bluetooth.h b/include/net/bluetooth/bluetooth.h
index bbefde319f95..3b2e59cedd2d 100644
--- a/include/net/bluetooth/bluetooth.h
+++ b/include/net/bluetooth/bluetooth.h
@@ -383,6 +383,7 @@ struct bt_sock {
 	struct list_head accept_q;
 	struct sock *parent;
 	unsigned long flags;
+	atomic_t bpf_tskey;
 	void (*skb_msg_name)(struct sk_buff *, void *, int *);
 	void (*skb_put_cmsg)(struct sk_buff *, struct msghdr *, struct sock *);
 };
diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index 95972fd4c784..7430df1c5822 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -28,6 +28,7 @@
 #include <linux/export.h>
 #include <linux/debugfs.h>
 #include <linux/errqueue.h>
+#include <linux/bpf-cgroup.h>
 
 #include <net/bluetooth/bluetooth.h>
 #include <net/bluetooth/hci_core.h>
@@ -3072,6 +3073,7 @@ void hci_setup_tx_timestamp(struct sk_buff *skb, size_t key_offset,
 			    const struct sockcm_cookie *sockc)
 {
 	struct sock *sk = skb ? skb->sk : NULL;
+	bool have_tskey = false;
 
 	/* This shall be called on a single skb of those generated by user
 	 * sendmsg(), and only when the sendmsg() does not return error to
@@ -3096,6 +3098,20 @@ void hci_setup_tx_timestamp(struct sk_buff *skb, size_t key_offset,
 
 			skb_shinfo(skb)->tskey = key - 1;
 		}
+		have_tskey = true;
+	}
+
+	if (cgroup_bpf_enabled(CGROUP_SOCK_OPS) &&
+	    SK_BPF_CB_FLAG_TEST(sk, SK_BPF_CB_TX_TIMESTAMPING)) {
+		struct bt_sock *bt_sk = container_of(sk, struct bt_sock, sk);
+		int key = atomic_inc_return(&bt_sk->bpf_tskey);
+
+		if (!have_tskey)
+			skb_shinfo(skb)->tskey = key - 1;
+
+		bpf_skops_tx_timestamping(sk, skb,
+					  BPF_SOCK_OPS_TSTAMP_SENDMSG_CB);
+
 	}
 }
 
@@ -3105,7 +3121,7 @@ void hci_conn_tx_queue(struct hci_conn *conn, struct sk_buff *skb)
 	bool track = false;
 
 	/* Emit SND now, ie. just before sending to driver */
-	if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP)
+	if (skb_shinfo(skb)->tx_flags & (SKBTX_SW_TSTAMP | SKBTX_BPF))
 		__skb_tstamp_tx(skb, NULL, NULL, skb->sk, SCM_TSTAMP_SND);
 
 	/* COMPLETION tstamp is emitted for tracked skb later in Number of
@@ -3127,7 +3143,8 @@ void hci_conn_tx_queue(struct hci_conn *conn, struct sk_buff *skb)
 		return;
 	}
 
-	if (skb->sk && (skb_shinfo(skb)->tx_flags & SKBTX_COMPLETION_TSTAMP))
+	if (skb->sk && (skb_shinfo(skb)->tx_flags &
+			(SKBTX_COMPLETION_TSTAMP | SKBTX_BPF)))
 		track = true;
 
 	/* If nothing is tracked, just count extra skbs at the queue head */
-- 
2.49.0