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77 lines
2.5 KiB
Diff
77 lines
2.5 KiB
Diff
From c685af47c8ba64119584512bb0881367c104e439 Mon Sep 17 00:00:00 2001
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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Thu, 21 Sep 2017 15:35:57 +0200
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Subject: [PATCH 061/418] Bluetooth: avoid recursive locking in
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hci_send_to_channel()
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Mart reported a deadlock in -RT in the call path:
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hci_send_monitor_ctrl_event() -> hci_send_to_channel()
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because both functions acquire the same read lock hci_sk_list.lock. This
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is also a mainline issue because the qrwlock implementation is writer
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fair (the traditional rwlock implementation is reader biased).
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To avoid the deadlock there is now __hci_send_to_channel() which expects
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the readlock to be held.
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Cc: Marcel Holtmann <marcel@holtmann.org>
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Cc: Johan Hedberg <johan.hedberg@intel.com>
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Cc: stable-rt@vger.kernel.org
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Fixes: 38ceaa00d02d ("Bluetooth: Add support for sending MGMT commands and events to monitor")
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Reported-by: Mart van de Wege <mvdwege@gmail.com>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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net/bluetooth/hci_sock.c | 17 +++++++++++------
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1 file changed, 11 insertions(+), 6 deletions(-)
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diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c
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index 65d734c165bd..923e9a271872 100644
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--- a/net/bluetooth/hci_sock.c
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+++ b/net/bluetooth/hci_sock.c
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@@ -251,15 +251,13 @@ void hci_send_to_sock(struct hci_dev *hdev, struct sk_buff *skb)
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}
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/* Send frame to sockets with specific channel */
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-void hci_send_to_channel(unsigned short channel, struct sk_buff *skb,
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- int flag, struct sock *skip_sk)
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+static void __hci_send_to_channel(unsigned short channel, struct sk_buff *skb,
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+ int flag, struct sock *skip_sk)
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{
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struct sock *sk;
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BT_DBG("channel %u len %d", channel, skb->len);
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- read_lock(&hci_sk_list.lock);
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-
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sk_for_each(sk, &hci_sk_list.head) {
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struct sk_buff *nskb;
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@@ -285,6 +283,13 @@ void hci_send_to_channel(unsigned short channel, struct sk_buff *skb,
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kfree_skb(nskb);
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}
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+}
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+
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+void hci_send_to_channel(unsigned short channel, struct sk_buff *skb,
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+ int flag, struct sock *skip_sk)
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+{
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+ read_lock(&hci_sk_list.lock);
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+ __hci_send_to_channel(channel, skb, flag, skip_sk);
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read_unlock(&hci_sk_list.lock);
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}
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@@ -388,8 +393,8 @@ void hci_send_monitor_ctrl_event(struct hci_dev *hdev, u16 event,
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hdr->index = index;
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hdr->len = cpu_to_le16(skb->len - HCI_MON_HDR_SIZE);
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- hci_send_to_channel(HCI_CHANNEL_MONITOR, skb,
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- HCI_SOCK_TRUSTED, NULL);
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+ __hci_send_to_channel(HCI_CHANNEL_MONITOR, skb,
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+ HCI_SOCK_TRUSTED, NULL);
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kfree_skb(skb);
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}
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--
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2.17.1
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