tree ea84fa4336bb56034a29e225b2c221cdd7c71673
parent 2e65c9d2c5206eb24439f2dd2daa2f6702df358e
author Andre Guedes <andre.guedes@openbossa.org> 1310045435 -0300
committer Gustavo F. Padovan <padovan@profusion.mobi> 1310059692 -0300

Bluetooth: Fix potential deadlock in hci_core

Since hdev->lock may be acquired by threads runnning in interrupt
context, all threads running in process context should disable
local bottom halve before locking hdev->lock. This can be done by
using hci_dev_lock_bh macro.

This way, we avoid potencial deadlocks like this one reported by
CONFIG_PROVE_LOCKING=y.

[  304.788780] =================================
[  304.789686] [ INFO: inconsistent lock state ]
[  304.789686] 2.6.39+ #1
[  304.789686] ---------------------------------
[  304.789686] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
[  304.789686] ksoftirqd/0/3 [HC0[0]:SC1[1]:HE1:SE0] takes:
[  304.789686]  (&(&hdev->lock)->rlock){+.?...}, at: [<ffffffffa000bbfe>] hci_conn_check_pending+0x38/0x76 [bluetooth]
[  304.789686] {SOFTIRQ-ON-W} state was registered at:
[  304.789686]   [<ffffffff8105188b>] __lock_acquire+0x347/0xd52
[  304.789686]   [<ffffffff810526ac>] lock_acquire+0x8a/0xa7
[  304.789686]   [<ffffffff812b3758>] _raw_spin_lock+0x2c/0x3b
[  304.789686]   [<ffffffffa0009cf0>] hci_blacklist_del+0x1f/0x8a [bluetooth]
[  304.789686]   [<ffffffffa00139fd>] hci_sock_ioctl+0x2d9/0x314 [bluetooth]
[  304.789686]   [<ffffffff812197d8>] sock_ioctl+0x1f2/0x214
[  304.789686]   [<ffffffff810b0fd6>] do_vfs_ioctl+0x46c/0x4ad
[  304.789686]   [<ffffffff810b1059>] sys_ioctl+0x42/0x65
[  304.789686]   [<ffffffff812b4892>] system_call_fastpath+0x16/0x1b
[  304.789686] irq event stamp: 9768
[  304.789686] hardirqs last  enabled at (9768): [<ffffffff812b40d4>] restore_args+0x0/0x30
[  304.789686] hardirqs last disabled at (9767): [<ffffffff812b3f6a>] save_args+0x6a/0x70
[  304.789686] softirqs last  enabled at (9726): [<ffffffff8102fa9b>] __do_softirq+0x129/0x13f
[  304.789686] softirqs last disabled at (9739): [<ffffffff8102fb33>] run_ksoftirqd+0x82/0x133
[  304.789686]
[  304.789686] other info that might help us debug this:
[  304.789686]  Possible unsafe locking scenario:
[  304.789686]
[  304.789686]        CPU0
[  304.789686]        ----
[  304.789686]   lock(&(&hdev->lock)->rlock);
[  304.789686]   <Interrupt>
[  304.789686]     lock(&(&hdev->lock)->rlock);
[  304.789686]
[  304.789686]  *** DEADLOCK ***
[  304.789686]
[  304.789686] 1 lock held by ksoftirqd/0/3:
[  304.789686]  #0:  (hci_task_lock){++.-..}, at: [<ffffffffa0008353>] hci_rx_task+0x49/0x2f3 [bluetooth]
[  304.789686]
[  304.789686] stack backtrace:
[  304.789686] Pid: 3, comm: ksoftirqd/0 Not tainted 2.6.39+ #1
[  304.789686] Call Trace:
[  304.789686]  [<ffffffff812ae901>] print_usage_bug+0x1e7/0x1f8
[  304.789686]  [<ffffffff8100a796>] ? save_stack_trace+0x27/0x44
[  304.789686]  [<ffffffff8104fc3f>] ? print_irq_inversion_bug.part.26+0x19a/0x19a
[  304.789686]  [<ffffffff810504bb>] mark_lock+0x106/0x258
[  304.789686]  [<ffffffff812b40d4>] ? retint_restore_args+0x13/0x13
[  304.789686]  [<ffffffff81051817>] __lock_acquire+0x2d3/0xd52
[  304.789686]  [<ffffffff8102be73>] ? vprintk+0x3ab/0x3d7
[  304.789686]  [<ffffffff812ae126>] ? printk+0x3c/0x3e
[  304.789686]  [<ffffffff810526ac>] lock_acquire+0x8a/0xa7
[  304.789686]  [<ffffffffa000bbfe>] ? hci_conn_check_pending+0x38/0x76 [bluetooth]
[  304.789686]  [<ffffffff811601c6>] ? __dynamic_pr_debug+0x10c/0x11a
[  304.789686]  [<ffffffff812b3758>] _raw_spin_lock+0x2c/0x3b
[  304.789686]  [<ffffffffa000bbfe>] ? hci_conn_check_pending+0x38/0x76 [bluetooth]
[  304.789686]  [<ffffffffa000bbfe>] hci_conn_check_pending+0x38/0x76 [bluetooth]
[  304.789686]  [<ffffffffa000c561>] hci_event_packet+0x38e/0x3e12 [bluetooth]
[  304.789686]  [<ffffffff81052615>] ? lock_release+0x16c/0x179
[  304.789686]  [<ffffffff812b3b41>] ? _raw_read_unlock+0x23/0x27
[  304.789686]  [<ffffffffa0013e7f>] ? hci_send_to_sock+0x179/0x188 [bluetooth]
[  304.789686]  [<ffffffffa00083d2>] hci_rx_task+0xc8/0x2f3 [bluetooth]
[  304.789686]  [<ffffffff8102f5a9>] tasklet_action+0x87/0xe6
[  304.789686]  [<ffffffff8102fa11>] __do_softirq+0x9f/0x13f
[  304.789686]  [<ffffffff8102fb33>] run_ksoftirqd+0x82/0x133
[  304.789686]  [<ffffffff8102fab1>] ? __do_softirq+0x13f/0x13f
[  304.789686]  [<ffffffff81040f0a>] kthread+0x7f/0x87
[  304.789686]  [<ffffffff812b55c4>] kernel_thread_helper+0x4/0x10
[  304.789686]  [<ffffffff812b40d4>] ? retint_restore_args+0x13/0x13
[  304.789686]  [<ffffffff81040e8b>] ? __init_kthread_worker+0x53/0x53
[  304.789686]  [<ffffffff812b55c0>] ? gs_change+0x13/0x13

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>