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authorAntti Palosaari <crope@iki.fi>2014-12-18 07:22:46 -0300
committerMauro Carvalho Chehab <mchehab@osg.samsung.com>2015-02-03 16:28:12 -0200
commitb410dae43cd0dc9aa07f9ada54a7b78d0fd75566 (patch)
tree68bf863cd31d490fbf9d2420b46e54f5d543981e /drivers/media
parent670ef05f829bcbab1548f6cdc93d522723c56fd3 (diff)
[media] rtl2832: implement own lock for regmap
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: Antti Palosaari <crope@iki.fi> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Diffstat (limited to 'drivers/media')
-rw-r--r--drivers/media/dvb-frontends/rtl2832.c48
-rw-r--r--drivers/media/dvb-frontends/rtl2832_priv.h2
2 files changed, 40 insertions, 10 deletions
diff --git a/drivers/media/dvb-frontends/rtl2832.c b/drivers/media/dvb-frontends/rtl2832.c
index eaa74b0c860..0f2a743bb19 100644
--- a/drivers/media/dvb-frontends/rtl2832.c
+++ b/drivers/media/dvb-frontends/rtl2832.c
@@ -1028,6 +1028,32 @@ static int rtl2832_regmap_gather_write(void *context, const void *reg,
return 0;
}
+/*
+ * FIXME: Hack. 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 is not deadlock. Proper fix is to make
+ * regmap aware of lockdep.
+ */
+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 +1212,6 @@ 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");
@@ -1213,8 +1230,19 @@ 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, &regmap_bus, client,
- &regmap_config);
+ &dev->regmap_config);
if (IS_ERR(dev->regmap)) {
ret = PTR_ERR(dev->regmap);
goto err_kfree;
diff --git a/drivers/media/dvb-frontends/rtl2832_priv.h b/drivers/media/dvb-frontends/rtl2832_priv.h
index 9ff4f653034..c3a922c3790 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;