linux-kernel - [PATCH v3 2/2] Bluetooth: Improve skb handling in mgmt_device

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Message-Id: <20220201201033.1332733-3-rad@semihalf.com>
Date:   Tue,  1 Feb 2022 20:10:33 +0000
From:   Radoslaw Biernacki <rad@...ihalf.com>
To:     linux-bluetooth <linux-bluetooth@...r.kernel.org>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        Marcel Holtmann <marcel@...tmann.org>
Cc:     CrosBT Upstreaming <chromeos-bluetooth-upstreaming@...omium.org>,
        Archie Pusaka <apusaka@...omium.org>,
        Miao-chen Chou <mcchou@...omium.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        upstream@...ihalf.com, Radoslaw Biernacki <rad@...ihalf.com>,
        Angela Czubak <acz@...ihalf.com>,
        Marek Maslanka <mm@...ihalf.com>
Subject: [PATCH v3 2/2] Bluetooth: Improve skb handling in mgmt_device_connected()

This patch introduce eir_skb_put_data() that can be used to simplify
operations on eir in goal of eliminating the necessity of intermediary
buffers.
eir_skb_put_data() is in pair to what eir_append_data() does with help of
eir_len, but without awkwardness when passing return value to skb_put() (as
it returns updated offset not size).

Signed-off-by: Radoslaw Biernacki <rad@...ihalf.com>
---
 net/bluetooth/eir.h  | 15 +++++++++++++++
 net/bluetooth/mgmt.c | 25 ++++++++-----------------
 2 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/net/bluetooth/eir.h b/net/bluetooth/eir.h
index e5876751f07e..43f1945bffc5 100644
--- a/net/bluetooth/eir.h
+++ b/net/bluetooth/eir.h
@@ -41,6 +41,21 @@ static inline u16 eir_append_le16(u8 *eir, u16 eir_len, u8 type, u16 data)
 	return eir_len;
 }
 
+static inline u16 eir_skb_put_data(struct sk_buff *skb, u8 type, u8 *data, u8 data_len)
+{
+	u8 *eir;
+	u16 eir_len;
+
+	eir_len	= eir_precalc_len(data_len);
+	eir = skb_put(skb, eir_len);
+	WARN_ON(sizeof(type) + data_len > U8_MAX);
+	eir[0] = sizeof(type) + data_len;
+	eir[1] = type;
+	memcpy(&eir[2], data, data_len);
+
+	return eir_len;
+}
+
 static inline void *eir_get_data(u8 *eir, size_t eir_len, u8 type,
 				 size_t *data_len)
 {
diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index 43ca228104ce..4a24159f7dd6 100644
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -9087,18 +9087,12 @@ void mgmt_device_connected(struct hci_dev *hdev, struct hci_conn *conn,
 		skb_put_data(skb, conn->le_adv_data, conn->le_adv_data_len);
 		eir_len = conn->le_adv_data_len;
 	} else {
-		if (name_len > 0) {
-			eir_len = eir_append_data(ev->eir, 0, EIR_NAME_COMPLETE,
-						  name, name_len);
-			skb_put(skb, eir_len);
-		}
+		if (name)
+			eir_len += eir_skb_put_data(skb, EIR_NAME_COMPLETE, name, name_len);
 
-		if (memcmp(conn->dev_class, "\0\0\0", 3) != 0) {
-			eir_len = eir_append_data(ev->eir, eir_len,
-						  EIR_CLASS_OF_DEV,
-						  conn->dev_class, 3);
-			skb_put(skb, 5);
-		}
+		if (memcmp(conn->dev_class, "\0\0\0", sizeof(conn->dev_class)))
+			eir_len += eir_skb_put_data(skb, EIR_CLASS_OF_DEV,
+						    conn->dev_class, sizeof(conn->dev_class));
 	}
 
 	ev->eir_len = cpu_to_le16(eir_len);
@@ -9798,13 +9792,10 @@ void mgmt_remote_name(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
 	ev->addr.type = link_to_bdaddr(link_type, addr_type);
 	ev->rssi = rssi;
 
-	if (name) {
-		eir_len = eir_append_data(ev->eir, 0, EIR_NAME_COMPLETE, name,
-					  name_len);
-		skb_put(skb, eir_len);
-	} else {
+	if (name)
+		eir_len += eir_skb_put_data(skb, EIR_NAME_COMPLETE, name, name_len);
+	else
 		flags = MGMT_DEV_FOUND_NAME_REQUEST_FAILED;
-	}
 
 	ev->eir_len = cpu_to_le16(eir_len);
 	ev->flags = cpu_to_le32(flags);
-- 
2.35.0.rc2.247.g8bbb082509-goog