4.4.102-rt117-rc1 stable review patch.
If anyone has any objections, please let me know.
------------------
From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Mart reported a deadlock in -RT in the call path:
hci_send_monitor_ctrl_event() -> hci_send_to_channel()
because both functions acquire the same read lock hci_sk_list.lock. This
is also a mainline issue because the qrwlock implementation is writer
fair (the traditional rwlock implementation is reader biased).
To avoid the deadlock there is now __hci_send_to_channel() which expects
the readlock to be held.
Cc: Marcel Holtmann <marcel@xxxxxxxxxxxx>
Cc: Johan Hedberg <johan.hedberg@xxxxxxxxx>
Cc: stable-rt@xxxxxxxxxxxxxxx
Fixes: 38ceaa00d02d ("Bluetooth: Add support for sending MGMT commands and events to monitor")
Reported-by: Mart van de Wege <mvdwege@xxxxxxxxx>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
net/bluetooth/hci_sock.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c
index c842f40c1173..035a5f6e3de9 100644
--- a/net/bluetooth/hci_sock.c
+++ b/net/bluetooth/hci_sock.c
@@ -213,15 +213,13 @@ void hci_send_to_sock(struct hci_dev *hdev, struct sk_buff *skb)
}
/* Send frame to sockets with specific channel */
-void hci_send_to_channel(unsigned short channel, struct sk_buff *skb,
- int flag, struct sock *skip_sk)
+static void __hci_send_to_channel(unsigned short channel, struct sk_buff *skb,
+ int flag, struct sock *skip_sk)
{
struct sock *sk;
BT_DBG("channel %u len %d", channel, skb->len);
- read_lock(&hci_sk_list.lock);
-
sk_for_each(sk, &hci_sk_list.head) {
struct sk_buff *nskb;
@@ -247,6 +245,13 @@ void hci_send_to_channel(unsigned short channel, struct sk_buff *skb,
kfree_skb(nskb);
}
+}
+
+void hci_send_to_channel(unsigned short channel, struct sk_buff *skb,
+ int flag, struct sock *skip_sk)
+{
+ read_lock(&hci_sk_list.lock);
+ __hci_send_to_channel(channel, skb, flag, skip_sk);
read_unlock(&hci_sk_list.lock);
}
@@ -299,8 +304,8 @@ void hci_send_to_monitor(struct hci_dev *hdev, struct sk_buff *skb)
hdr->index = cpu_to_le16(hdev->id);
hdr->len = cpu_to_le16(skb->len);
- hci_send_to_channel(HCI_CHANNEL_MONITOR, skb_copy,
- HCI_SOCK_TRUSTED, NULL);
+ __hci_send_to_channel(HCI_CHANNEL_MONITOR, skb_copy,
+ HCI_SOCK_TRUSTED, NULL);
kfree_skb(skb_copy);
}
--
2.13.2
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