Revert "Revert "Bluetooth: hci_core: Fix sleeping function called from invalid context""

This reverts commit 55b098a2be which is
commit ab6ab707a4d060a51c45fc13e3b2228d5f7c0b87 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: I16716919ad640cccea5ecbfd92fbe185333024e9
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

include/net/bluetooth/hci_core.h

@@ -803,7 +803,6 @@ struct hci_conn_params {
 extern struct list_head hci_dev_list;
 extern struct list_head hci_cb_list;
 extern rwlock_t hci_dev_list_lock;
-extern struct mutex hci_cb_list_lock;
 
 #define hci_dev_set_flag(hdev, nr)             set_bit((nr), (hdev)->dev_flags)
 #define hci_dev_clear_flag(hdev, nr)           clear_bit((nr), (hdev)->dev_flags)
@@ -2006,24 +2005,47 @@ struct hci_cb {
 
 	char *name;
 
+	bool (*match)		(struct hci_conn *conn);
 	void (*connect_cfm)	(struct hci_conn *conn, __u8 status);
 	void (*disconn_cfm)	(struct hci_conn *conn, __u8 status);
 	void (*security_cfm)	(struct hci_conn *conn, __u8 status,
-								__u8 encrypt);
+				 __u8 encrypt);
 	void (*key_change_cfm)	(struct hci_conn *conn, __u8 status);
 	void (*role_switch_cfm)	(struct hci_conn *conn, __u8 status, __u8 role);
 };
 
+static inline void hci_cb_lookup(struct hci_conn *conn, struct list_head *list)
+{
+	struct hci_cb *cb, *cpy;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(cb, &hci_cb_list, list) {
+		if (cb->match && cb->match(conn)) {
+			cpy = kmalloc(sizeof(*cpy), GFP_ATOMIC);
+			if (!cpy)
+				break;
+
+			*cpy = *cb;
+			INIT_LIST_HEAD(&cpy->list);
+			list_add_rcu(&cpy->list, list);
+		}
+	}
+	rcu_read_unlock();
+}
+
 static inline void hci_connect_cfm(struct hci_conn *conn, __u8 status)
 {
-	struct hci_cb *cb;
+	struct list_head list;
+	struct hci_cb *cb, *tmp;
 
-	mutex_lock(&hci_cb_list_lock);
-	list_for_each_entry(cb, &hci_cb_list, list) {
+	INIT_LIST_HEAD(&list);
+	hci_cb_lookup(conn, &list);
+
+	list_for_each_entry_safe(cb, tmp, &list, list) {
 		if (cb->connect_cfm)
 			cb->connect_cfm(conn, status);
+		kfree(cb);
 	}
-	mutex_unlock(&hci_cb_list_lock);
 
 	if (conn->connect_cfm_cb)
 		conn->connect_cfm_cb(conn, status);
@@ -2031,22 +2053,43 @@ static inline void hci_connect_cfm(struct hci_conn *conn, __u8 status)
 
 static inline void hci_disconn_cfm(struct hci_conn *conn, __u8 reason)
 {
-	struct hci_cb *cb;
+	struct list_head list;
+	struct hci_cb *cb, *tmp;
 
-	mutex_lock(&hci_cb_list_lock);
-	list_for_each_entry(cb, &hci_cb_list, list) {
+	INIT_LIST_HEAD(&list);
+	hci_cb_lookup(conn, &list);
+
+	list_for_each_entry_safe(cb, tmp, &list, list) {
 		if (cb->disconn_cfm)
 			cb->disconn_cfm(conn, reason);
+		kfree(cb);
 	}
-	mutex_unlock(&hci_cb_list_lock);
 
 	if (conn->disconn_cfm_cb)
 		conn->disconn_cfm_cb(conn, reason);
 }
 
+static inline void hci_security_cfm(struct hci_conn *conn, __u8 status,
+				    __u8 encrypt)
+{
+	struct list_head list;
+	struct hci_cb *cb, *tmp;
+
+	INIT_LIST_HEAD(&list);
+	hci_cb_lookup(conn, &list);
+
+	list_for_each_entry_safe(cb, tmp, &list, list) {
+		if (cb->security_cfm)
+			cb->security_cfm(conn, status, encrypt);
+		kfree(cb);
+	}
+
+	if (conn->security_cfm_cb)
+		conn->security_cfm_cb(conn, status);
+}
+
 static inline void hci_auth_cfm(struct hci_conn *conn, __u8 status)
 {
-	struct hci_cb *cb;
 	__u8 encrypt;
 
 	if (test_bit(HCI_CONN_ENCRYPT_PEND, &conn->flags))
@@ -2054,20 +2097,11 @@ static inline void hci_auth_cfm(struct hci_conn *conn, __u8 status)
 
 	encrypt = test_bit(HCI_CONN_ENCRYPT, &conn->flags) ? 0x01 : 0x00;
 
-	mutex_lock(&hci_cb_list_lock);
-	list_for_each_entry(cb, &hci_cb_list, list) {
-		if (cb->security_cfm)
-			cb->security_cfm(conn, status, encrypt);
-	}
-	mutex_unlock(&hci_cb_list_lock);
-
-	if (conn->security_cfm_cb)
-		conn->security_cfm_cb(conn, status);
+	hci_security_cfm(conn, status, encrypt);
 }
 
 static inline void hci_encrypt_cfm(struct hci_conn *conn, __u8 status)
 {
-	struct hci_cb *cb;
 	__u8 encrypt;
 
 	if (conn->state == BT_CONFIG) {
@@ -2094,40 +2128,38 @@ static inline void hci_encrypt_cfm(struct hci_conn *conn, __u8 status)
 			conn->sec_level = conn->pending_sec_level;
 	}
 
-	mutex_lock(&hci_cb_list_lock);
-	list_for_each_entry(cb, &hci_cb_list, list) {
-		if (cb->security_cfm)
-			cb->security_cfm(conn, status, encrypt);
-	}
-	mutex_unlock(&hci_cb_list_lock);
-
-	if (conn->security_cfm_cb)
-		conn->security_cfm_cb(conn, status);
+	hci_security_cfm(conn, status, encrypt);
 }
 
 static inline void hci_key_change_cfm(struct hci_conn *conn, __u8 status)
 {
-	struct hci_cb *cb;
+	struct list_head list;
+	struct hci_cb *cb, *tmp;
 
-	mutex_lock(&hci_cb_list_lock);
-	list_for_each_entry(cb, &hci_cb_list, list) {
+	INIT_LIST_HEAD(&list);
+	hci_cb_lookup(conn, &list);
+
+	list_for_each_entry_safe(cb, tmp, &list, list) {
 		if (cb->key_change_cfm)
 			cb->key_change_cfm(conn, status);
+		kfree(cb);
 	}
-	mutex_unlock(&hci_cb_list_lock);
 }
 
 static inline void hci_role_switch_cfm(struct hci_conn *conn, __u8 status,
 								__u8 role)
 {
-	struct hci_cb *cb;
+	struct list_head list;
+	struct hci_cb *cb, *tmp;
 
-	mutex_lock(&hci_cb_list_lock);
-	list_for_each_entry(cb, &hci_cb_list, list) {
+	INIT_LIST_HEAD(&list);
+	hci_cb_lookup(conn, &list);
+
+	list_for_each_entry_safe(cb, tmp, &list, list) {
 		if (cb->role_switch_cfm)
 			cb->role_switch_cfm(conn, status, role);
+		kfree(cb);
 	}
-	mutex_unlock(&hci_cb_list_lock);
 }
 
 static inline bool hci_bdaddr_is_rpa(bdaddr_t *bdaddr, u8 addr_type)

net/bluetooth/hci_core.c

@@ -57,7 +57,6 @@ DEFINE_RWLOCK(hci_dev_list_lock);
 
 /* HCI callback list */
 LIST_HEAD(hci_cb_list);
-DEFINE_MUTEX(hci_cb_list_lock);
 
 /* HCI ID Numbering */
 static DEFINE_IDA(hci_index_ida);
@@ -2993,9 +2992,7 @@ int hci_register_cb(struct hci_cb *cb)
 {
 	BT_DBG("%p name %s", cb, cb->name);
 
-	mutex_lock(&hci_cb_list_lock);
-	list_add_tail(&cb->list, &hci_cb_list);
-	mutex_unlock(&hci_cb_list_lock);
+	list_add_tail_rcu(&cb->list, &hci_cb_list);
 
 	return 0;
 }
@@ -3005,9 +3002,8 @@ int hci_unregister_cb(struct hci_cb *cb)
 {
 	BT_DBG("%p name %s", cb, cb->name);
 
-	mutex_lock(&hci_cb_list_lock);
-	list_del(&cb->list);
-	mutex_unlock(&hci_cb_list_lock);
+	list_del_rcu(&cb->list);
+	synchronize_rcu();
 
 	return 0;
 }

net/bluetooth/iso.c

@@ -2137,6 +2137,11 @@ done:
 	return HCI_LM_ACCEPT;
 }
 
+static bool iso_match(struct hci_conn *hcon)
+{
+	return hcon->type == ISO_LINK || hcon->type == LE_LINK;
+}
+
 static void iso_connect_cfm(struct hci_conn *hcon, __u8 status)
 {
 	if (hcon->type != ISO_LINK) {
@@ -2318,6 +2323,7 @@ drop:
 
 static struct hci_cb iso_cb = {
 	.name		= "ISO",
+	.match		= iso_match,
 	.connect_cfm	= iso_connect_cfm,
 	.disconn_cfm	= iso_disconn_cfm,
 };

net/bluetooth/l2cap_core.c

@@ -7222,6 +7222,11 @@ static struct l2cap_chan *l2cap_global_fixed_chan(struct l2cap_chan *c,
 	return NULL;
 }
 
+static bool l2cap_match(struct hci_conn *hcon)
+{
+	return hcon->type == ACL_LINK || hcon->type == LE_LINK;
+}
+
 static void l2cap_connect_cfm(struct hci_conn *hcon, u8 status)
 {
 	struct hci_dev *hdev = hcon->hdev;
@@ -7229,9 +7234,6 @@ static void l2cap_connect_cfm(struct hci_conn *hcon, u8 status)
 	struct l2cap_chan *pchan;
 	u8 dst_type;
 
-	if (hcon->type != ACL_LINK && hcon->type != LE_LINK)
-		return;
-
 	BT_DBG("hcon %p bdaddr %pMR status %d", hcon, &hcon->dst, status);
 
 	if (status) {
@@ -7296,9 +7298,6 @@ int l2cap_disconn_ind(struct hci_conn *hcon)
 
 static void l2cap_disconn_cfm(struct hci_conn *hcon, u8 reason)
 {
-	if (hcon->type != ACL_LINK && hcon->type != LE_LINK)
-		return;
-
 	BT_DBG("hcon %p reason %d", hcon, reason);
 
 	l2cap_conn_del(hcon, bt_to_errno(reason));
@@ -7577,6 +7576,7 @@ drop:
 
 static struct hci_cb l2cap_cb = {
 	.name		= "L2CAP",
+	.match		= l2cap_match,
 	.connect_cfm	= l2cap_connect_cfm,
 	.disconn_cfm	= l2cap_disconn_cfm,
 	.security_cfm	= l2cap_security_cfm,

net/bluetooth/rfcomm/core.c

@@ -2134,6 +2134,11 @@ static int rfcomm_run(void *unused)
 	return 0;
 }
 
+static bool rfcomm_match(struct hci_conn *hcon)
+{
+	return hcon->type == ACL_LINK;
+}
+
 static void rfcomm_security_cfm(struct hci_conn *conn, u8 status, u8 encrypt)
 {
 	struct rfcomm_session *s;
@@ -2180,6 +2185,7 @@ static void rfcomm_security_cfm(struct hci_conn *conn, u8 status, u8 encrypt)
 
 static struct hci_cb rfcomm_cb = {
 	.name		= "RFCOMM",
+	.match		= rfcomm_match,
 	.security_cfm	= rfcomm_security_cfm
 };
 

net/bluetooth/sco.c

@@ -1355,11 +1355,13 @@ int sco_connect_ind(struct hci_dev *hdev, bdaddr_t *bdaddr, __u8 *flags)
 	return lm;
 }
 
+static bool sco_match(struct hci_conn *hcon)
+{
+	return hcon->type == SCO_LINK || hcon->type == ESCO_LINK;
+}
+
 static void sco_connect_cfm(struct hci_conn *hcon, __u8 status)
 {
-	if (hcon->type != SCO_LINK && hcon->type != ESCO_LINK)
-		return;
-
 	BT_DBG("hcon %p bdaddr %pMR status %u", hcon, &hcon->dst, status);
 
 	if (!status) {
@@ -1374,9 +1376,6 @@ static void sco_connect_cfm(struct hci_conn *hcon, __u8 status)
 
 static void sco_disconn_cfm(struct hci_conn *hcon, __u8 reason)
 {
-	if (hcon->type != SCO_LINK && hcon->type != ESCO_LINK)
-		return;
-
 	BT_DBG("hcon %p reason %d", hcon, reason);
 
 	sco_conn_del(hcon, bt_to_errno(reason));
@@ -1402,6 +1401,7 @@ drop:
 
 static struct hci_cb sco_cb = {
 	.name		= "SCO",
+	.match		= sco_match,
 	.connect_cfm	= sco_connect_cfm,
 	.disconn_cfm	= sco_disconn_cfm,
 };