Hi Jukka,
On 10/15/2014 08:43 AM, Jukka Rissanen wrote:
> Use spin_lock_irqsave() when sending data to hci channel. Otherwise
> the lockdep gives inconsistent lock state warning when sending data
> to 6lowpan channel.
>
> [ INFO: inconsistent lock state ]
> 3.17.0-rc1-bt6lowpan #1 Not tainted
> ---------------------------------
> inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage.
> kworker/u3:0/321 [HC0[0]:SC0[0]:HE1:SE1] takes:
> (&(&list->lock)->rlock#6){+.?...}, at: [<f845fdac>] hci_send_acl+0xac/0x290 [bluetooth]
> {IN-SOFTIRQ-W} state was registered at:
> [<c10915a3>] __lock_acquire+0x6d3/0x1d20
> [<c109325d>] lock_acquire+0x9d/0x140
> [<c1889c25>] _raw_spin_lock+0x45/0x80
> [<f845fdac>] hci_send_acl+0xac/0x290 [bluetooth]
> [<f8480c60>] l2cap_do_send+0x60/0x100 [bluetooth]
> [<f8484830>] l2cap_chan_send+0x7f0/0x10e0 [bluetooth]
> [<f873191e>] send_pkt+0x4e/0xa0 [bluetooth_6lowpan]
> [<f8731d20>] bt_xmit+0x3b0/0x770 [bluetooth_6lowpan]
> [<c17742f4>] dev_hard_start_xmit+0x344/0x670
> [<c17749ad>] __dev_queue_xmit+0x38d/0x680
> [<c1774caf>] dev_queue_xmit+0xf/0x20
> [<c177b8b0>] neigh_connected_output+0x130/0x1a0
> [<c1812a63>] ip6_finish_output2+0x173/0x8c0
> [<c18182db>] ip6_finish_output+0x7b/0x1b0
> [<c18184a7>] ip6_output+0x97/0x2a0
> [<c183a46b>] mld_sendpack+0x5eb/0x650
> [<c183acc1>] mld_ifc_timer_expire+0x191/0x2f0
> [<c10ac385>] call_timer_fn+0x85/0x1c0
> [<c10acb72>] run_timer_softirq+0x192/0x280
> [<c104fd84>] __do_softirq+0xd4/0x300
> [<c10049fc>] do_softirq_own_stack+0x2c/0x40
> [<c1050136>] irq_exit+0x86/0xb0
> [<c188bd98>] smp_apic_timer_interrupt+0x38/0x50
> [<c188b6ce>] apic_timer_interrupt+0x32/0x38
>
> Signed-off-by: Jukka Rissanen <jukka.rissanen@xxxxxxxxxxxxxxx>
> ---
> Hi,
>
> this patch fixes the locking issue when sending larger amount of
> data via 6lowpan link. After this patch the lockdep no longer warns
> about softirq issues.
>
> Cheers,
> Jukka
>
>
> net/bluetooth/hci_core.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> index 8aea4be..3e295ff 100644
> --- a/net/bluetooth/hci_core.c
> +++ b/net/bluetooth/hci_core.c
> @@ -4642,6 +4642,7 @@ static void hci_queue_acl(struct hci_chan *chan, struct sk_buff_head *queue,
> struct hci_conn *conn = chan->conn;
> struct hci_dev *hdev = conn->hdev;
> struct sk_buff *list;
> + unsigned long irq_flags;
>
> skb->len = skb_headlen(skb);
> skb->data_len = 0;
> @@ -4673,7 +4674,7 @@ static void hci_queue_acl(struct hci_chan *chan, struct sk_buff_head *queue,
> skb_shinfo(skb)->frag_list = NULL;
>
> /* Queue all fragments atomically */
> - spin_lock(&queue->lock);
> + spin_lock_irqsave(&queue->lock, irq_flags);
spin_lock_bh(&queue->lock) will suffice.
Also, please consider submitting a patch to netdev to document the lock
requirement with the struct sk_buff_head definition.
Regards,
Peter Hurley
>
> __skb_queue_tail(queue, skb);
>
> @@ -4690,7 +4691,7 @@ static void hci_queue_acl(struct hci_chan *chan, struct sk_buff_head *queue,
> __skb_queue_tail(queue, skb);
> } while (list);
>
> - spin_unlock(&queue->lock);
> + spin_unlock_irqrestore(&queue->lock, irq_flags);
> }
> }
>
>
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