• Antti Palosaari's avatar
    [media] rtl2832: implement own lock for regmap · b410dae4
    Antti Palosaari authored
    Introduce own lock to silence lockdep warning. lockdep validator
    makes wrong decision when two similar (&map->mutex) locks were taken
    recursively, even those are different mutexes in a two different
    drivers. After that patch, functionality remains same, but mutex names
    are different. That is a temporary hack, proper solution is make
    regmap aware of locked nested locking rules.
    
    =============================================
    [ INFO: possible recursive locking detected ]
    3.18.0-rc4+ #4 Tainted: G           O
    ---------------------------------------------
    kdvb-ad-0-fe-0/2814 is trying to acquire lock:
     (&map->mutex){+.+.+.}, at: [<ffffffff814ec90f>] regmap_lock_mutex+0x2f/0x40
    
    but task is already holding lock:
     (&map->mutex){+.+.+.}, at: [<ffffffff814ec90f>] regmap_lock_mutex+0x2f/0x40
    
    other info that might help us debug this:
     Possible unsafe locking scenario:
           CPU0
           ----
      lock(&map->mutex);
      lock(&map->mutex);
    
     *** DEADLOCK ***
     May be due to missing lock nesting notation
    1 lock held by kdvb-ad-0-fe-0/2814:
     #0:  (&map->mutex){+.+.+.}, at: [<ffffffff814ec90f>] regmap_lock_mutex+0x2f/0x40
    
    stack backtrace:
    CPU: 3 PID: 2814 Comm: kdvb-ad-0-fe-0 Tainted: G           O 3.18.0-rc4+ #4
    Hardware name: System manufacturer System Product Name/M5A78L-M/USB3, BIOS 2001    09/11/2014
     0000000000000000 00000000410c8772 ffff880293af3868 ffffffff817a6f82
     0000000000000000 ffff8800b3462be0 ffff880293af3968 ffffffff810e7f94
     ffff880293af3888 00000000410c8772 ffffffff82dfee60 ffffffff81ab8f89
    Call Trace:
     [<ffffffff817a6f82>] dump_stack+0x4e/0x68
     [<ffffffff810e7f94>] __lock_acquire+0x1ea4/0x1f50
     [<ffffffff810e2a7d>] ? trace_hardirqs_off+0xd/0x10
     [<ffffffff817b01f3>] ? _raw_spin_lock_irqsave+0x83/0xa0
     [<ffffffff810e13e6>] ? up+0x16/0x50
     [<ffffffff810e2a7d>] ? trace_hardirqs_off+0xd/0x10
     [<ffffffff817af8bf>] ? _raw_spin_unlock_irqrestore+0x5f/0x70
     [<ffffffff810e9069>] lock_acquire+0xc9/0x170
     [<ffffffff814ec90f>] ? regmap_lock_mutex+0x2f/0x40
     [<ffffffff817ab50e>] mutex_lock_nested+0x7e/0x430
     [<ffffffff814ec90f>] ? regmap_lock_mutex+0x2f/0x40
     [<ffffffff814ec90f>] ? regmap_lock_mutex+0x2f/0x40
     [<ffffffff817a530b>] ? printk+0x70/0x86
     [<ffffffff8110d9e8>] ? mod_timer+0x168/0x240
     [<ffffffff814ec90f>] regmap_lock_mutex+0x2f/0x40
     [<ffffffff814f08d9>] regmap_update_bits+0x29/0x60
     [<ffffffffa03e9778>] rtl2832_select+0x38/0x70 [rtl2832]
     [<ffffffffa039b03d>] i2c_mux_master_xfer+0x3d/0x90 [i2c_mux]
     [<ffffffff815da493>] __i2c_transfer+0x73/0x2e0
     [<ffffffff815dbaba>] i2c_transfer+0x5a/0xc0
     [<ffffffff815dbb6e>] i2c_master_send+0x4e/0x70
     [<ffffffffa03ff25a>] regmap_i2c_write+0x1a/0x50 [regmap_i2c]
     [<ffffffff817ab713>] ? mutex_lock_nested+0x283/0x430
     [<ffffffff814f06b2>] _regmap_raw_write+0x862/0x880
     [<ffffffff814ec90f>] ? regmap_lock_mutex+0x2f/0x40
     [<ffffffff814f0744>] _regmap_bus_raw_write+0x74/0xa0
     [<ffffffff814ef3d2>] _regmap_write+0x92/0x140
     [<ffffffff814f0b7b>] regmap_write+0x4b/0x70
     [<ffffffffa032b090>] ? dvb_frontend_release+0x110/0x110 [dvb_core]
     [<ffffffffa05141d4>] e4000_init+0x34/0x210 [e4000]
     [<ffffffffa032a029>] dvb_frontend_init+0x59/0xc0 [dvb_core]
     [<ffffffff810bde30>] ? finish_task_switch+0x80/0x180
     [<ffffffff810bddf2>] ? finish_task_switch+0x42/0x180
     [<ffffffffa032b116>] dvb_frontend_thread+0x86/0x7b0 [dvb_core]
     [<ffffffff817a9203>] ? __schedule+0x343/0x930
     [<ffffffffa032b090>] ? dvb_frontend_release+0x110/0x110 [dvb_core]
     [<ffffffff810b826b>] kthread+0x10b/0x130
     [<ffffffff81020099>] ? sched_clock+0x9/0x10
     [<ffffffff810b8160>] ? kthread_create_on_node+0x250/0x250
     [<ffffffff817b063c>] ret_from_fork+0x7c/0xb0
     [<ffffffff810b8160>] ? kthread_create_on_node+0x250/0x250
    Signed-off-by: default avatarAntti Palosaari <crope@iki.fi>
    Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@osg.samsung.com>
    b410dae4
rtl2832.c 32.8 KB