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| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2017-09-21 16:51:23 +0300 |
|---|---|---|
| committer | Marcel Holtmann <marcel@holtmann.org> | 2017-10-30 11:04:07 +0300 |
| commit | a9ee77af751f435675054f5a7e2d2e69cbfe9e33 (patch) | |
| tree | 75d3524a3d20e74e4d34d0e43b3f9b6ff41fe0cb /net | |
| parent | 1f01d8be0e6a04bd682a55f6d50c14c1679e7571 (diff) | |
| download | linux-a9ee77af751f435675054f5a7e2d2e69cbfe9e33.tar.xz | |
Bluetooth: avoid recursive locking in hci_send_to_channel()
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.
Fixes: 38ceaa00d02d ("Bluetooth: Add support for sending MGMT commands and events to monitor")
Reported-by: Mart van de Wege <mvdwege@gmail.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/bluetooth/hci_sock.c | 17 |
1 files changed, 11 insertions, 6 deletions
diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c index 65d734c165bd..923e9a271872 100644 --- a/net/bluetooth/hci_sock.c +++ b/net/bluetooth/hci_sock.c @@ -251,15 +251,13 @@ 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; @@ -285,6 +283,13 @@ 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); } @@ -388,8 +393,8 @@ void hci_send_monitor_ctrl_event(struct hci_dev *hdev, u16 event, hdr->index = index; hdr->len = cpu_to_le16(skb->len - HCI_MON_HDR_SIZE); - hci_send_to_channel(HCI_CHANNEL_MONITOR, skb, - HCI_SOCK_TRUSTED, NULL); + __hci_send_to_channel(HCI_CHANNEL_MONITOR, skb, + HCI_SOCK_TRUSTED, NULL); kfree_skb(skb); } |