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From:   Luiz Augusto von Dentz <luiz.dentz@gmail.com>
To:     linux-bluetooth@vger.kernel.org
Subject: [PATCH 1/4] Bluetooth: Add bt_skb_sendmsg helper
Date:   Tue, 31 Aug 2021 17:26:18 -0700
Message-Id: <20210901002621.414016-1-luiz.dentz@gmail.com>
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From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

bt_skb_sendmsg helps takes care of allocation the skb and copying the
the contents of msg over to the skb while checking for possible errors
so it should be safe to call it without holding lock_sock.

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 include/net/bluetooth/bluetooth.h | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/include/net/bluetooth/bluetooth.h b/include/net/bluetooth/bluetooth.h
index 9125effbf448..f858efcf9f40 100644
--- a/include/net/bluetooth/bluetooth.h
+++ b/include/net/bluetooth/bluetooth.h
@@ -420,6 +420,32 @@ static inline struct sk_buff *bt_skb_send_alloc(struct sock *sk,
 	return NULL;
 }
 
+/* Shall not be called with lock_sock held */
+static inline struct sk_buff *bt_skb_sendmsg(struct sock *sk,
+					     struct msghdr *msg,
+					     size_t len, size_t header,
+					     size_t footer)
+{
+	struct sk_buff *skb;
+	int err;
+
+	skb = bt_skb_send_alloc(sk, len + header + footer,
+				msg->msg_flags & MSG_DONTWAIT, &err);
+	if (!skb)
+		return ERR_PTR(err);
+
+	skb_reserve(skb, header);
+
+	if (memcpy_from_msg(skb_put(skb, len), msg, len)) {
+		kfree_skb(skb);
+		return ERR_PTR(-EFAULT);
+	}
+
+	skb->priority = sk->sk_priority;
+
+	return skb;
+}
+
 int bt_to_errno(u16 code);
 
 void hci_sock_set_flag(struct sock *sk, int nr);
-- 
2.31.1