Introduce own lock to silence locdep warning. I suspect lockdep checks
make wrong decision when two similar name (&map->mutex) locks were
taken recursively, even those are different mutexes in a two different
driver. After that patch, functionality remains same, but mutex names
are different.
=============================================
[ 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: Antti Palosaari <crope@xxxxxx>
---
drivers/media/dvb-frontends/rtl2832.c | 49 +++++++++++++++++++++++-------
drivers/media/dvb-frontends/rtl2832_priv.h | 2 ++
2 files changed, 40 insertions(+), 11 deletions(-)
diff --git a/drivers/media/dvb-frontends/rtl2832.c b/drivers/media/dvb-frontends/rtl2832.c
index f44dc50..2ee5bcf 100644
--- a/drivers/media/dvb-frontends/rtl2832.c
+++ b/drivers/media/dvb-frontends/rtl2832.c
@@ -1028,6 +1028,31 @@ static int rtl2832_regmap_gather_write(void *context, const void *reg,
return 0;
}
+/*
+ * FIXME: Implement own RegMap locking in order to silence lockdep recursive
+ * lock warning. That happens when RegMap I2C client calls I2C mux adapter,
+ * which leads demod I2C repeater enable via demod RegMap. Operation takes two
+ * RegMap locks recursively - but those are different RegMap instances in a two
+ * different I2C drivers, so it should be deadlock.
+ */
+static void rtl2832_regmap_lock(void *__dev)
+{
+ struct rtl2832_dev *dev = __dev;
+ struct i2c_client *client = dev->client;
+
+ dev_dbg(&client->dev, "\n");
+ mutex_lock(&dev->regmap_mutex);
+}
+
+static void rtl2832_regmap_unlock(void *__dev)
+{
+ struct rtl2832_dev *dev = __dev;
+ struct i2c_client *client = dev->client;
+
+ dev_dbg(&client->dev, "\n");
+ mutex_unlock(&dev->regmap_mutex);
+}
+
static struct dvb_frontend *rtl2832_get_dvb_frontend(struct i2c_client *client)
{
struct rtl2832_dev *dev = i2c_get_clientdata(client);
@@ -1186,15 +1211,6 @@ static int rtl2832_probe(struct i2c_client *client,
.range_max = 5 * 0x100,
},
};
- static const struct regmap_config regmap_config = {
- .reg_bits = 8,
- .val_bits = 8,
- .volatile_reg = rtl2832_volatile_reg,
- .max_register = 5 * 0x100,
- .ranges = regmap_range_cfg,
- .num_ranges = ARRAY_SIZE(regmap_range_cfg),
- .cache_type = REGCACHE_RBTREE,
- };
dev_dbg(&client->dev, "\n");
@@ -1218,8 +1234,19 @@ static int rtl2832_probe(struct i2c_client *client,
INIT_DELAYED_WORK(&dev->i2c_gate_work, rtl2832_i2c_gate_work);
INIT_DELAYED_WORK(&dev->stat_work, rtl2832_stat_work);
/* create RegMap */
+ mutex_init(&dev->regmap_mutex);
+ dev->regmap_config.reg_bits = 8,
+ dev->regmap_config.val_bits = 8,
+ dev->regmap_config.lock = rtl2832_regmap_lock,
+ dev->regmap_config.unlock = rtl2832_regmap_unlock,
+ dev->regmap_config.lock_arg = dev,
+ dev->regmap_config.volatile_reg = rtl2832_volatile_reg,
+ dev->regmap_config.max_register = 5 * 0x100,
+ dev->regmap_config.ranges = regmap_range_cfg,
+ dev->regmap_config.num_ranges = ARRAY_SIZE(regmap_range_cfg),
+ dev->regmap_config.cache_type = REGCACHE_RBTREE,
dev->regmap = regmap_init(&client->dev, ®map_bus, client,
- ®map_config);
+ &dev->regmap_config);
if (IS_ERR(dev->regmap)) {
ret = PTR_ERR(dev->regmap);
goto err_kfree;
@@ -1232,7 +1259,7 @@ static int rtl2832_probe(struct i2c_client *client,
/* create muxed i2c adapter for demod tuner bus */
dev->i2c_adapter_tuner = i2c_add_mux_adapter(i2c, &i2c->dev, dev,
- 0, 0, 0, rtl2832_select, rtl2832_deselect);
+ 0, 1, 0, rtl2832_select, rtl2832_deselect);
if (dev->i2c_adapter_tuner == NULL) {
ret = -ENODEV;
goto err_regmap_exit;
diff --git a/drivers/media/dvb-frontends/rtl2832_priv.h b/drivers/media/dvb-frontends/rtl2832_priv.h
index 9ff4f65..c3a922c 100644
--- a/drivers/media/dvb-frontends/rtl2832_priv.h
+++ b/drivers/media/dvb-frontends/rtl2832_priv.h
@@ -33,6 +33,8 @@
struct rtl2832_dev {
struct rtl2832_platform_data *pdata;
struct i2c_client *client;
+ struct mutex regmap_mutex;
+ struct regmap_config regmap_config;
struct regmap *regmap;
struct i2c_adapter *i2c_adapter_tuner;
struct dvb_frontend fe;
--
http://palosaari.fi/
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