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i2c: Prevent priority inversion on top of bus lock

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Low priority thread holding the i2c bus mutex could block higher
priority threads to access the bus resulting in unacceptable
latencies. Change the mutex type to rt_mutex preventing priority
inversion.

Tested-by: Peter Ujfalusi <peter.ujfalusi@nokia.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala@nokia.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
This commit is contained in:
Mika Kuoppala 2009-12-06 17:06:22 +01:00 • committed by Jean Delvare
parent a0c11cdd6a
commit 194684e596
3 changed files with 10 additions and 10 deletions
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7
include/linux/i2c.h
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@ -338,8 +338,7 @@ struct i2c_adapter {
void *algo_data;
/* data fields that are valid for all devices */
u8 level; /* nesting level for lockdep */
struct mutex bus_lock;
struct rt_mutex bus_lock;
int timeout; /* in jiffies */
int retries;
@ -367,7 +366,7 @@ static inline void i2c_set_adapdata(struct i2c_adapter *dev, void *data)
*/
static inline void i2c_lock_adapter(struct i2c_adapter *adapter)
{
mutex_lock(&adapter->bus_lock);
rt_mutex_lock(&adapter->bus_lock);
}
/**
@ -376,7 +375,7 @@ static inline void i2c_lock_adapter(struct i2c_adapter *adapter)
*/
static inline void i2c_unlock_adapter(struct i2c_adapter *adapter)
{
mutex_unlock(&adapter->bus_lock);
rt_mutex_unlock(&adapter->bus_lock);
}
/*flags for the client struct: */