Confirm that 4.11.12-rt14 with this fix boots normally. On Thu, 21 Sep 2017 15:51:23 +0200 Sebastian Andrzej Siewior <[email protected]> wrote:
> 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 <[email protected]> > Cc: Johan Hedberg <[email protected]> > Fixes: 38ceaa00d02d ("Bluetooth: Add support for sending MGMT > commands and events to monitor") Reported-by: Mart van de Wege > <[email protected]> Signed-off-by: Sebastian Andrzej Siewior > <[email protected]> --- > 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 638bf0e1a2e3..f1ee820d871c 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); > } >
