RFH: Converting a driver from semaphore to mutex in 2.6.21

From: Martijn Uffing
Date: Thu Jul 12 2007 - 08:54:59 EST


Ave lkml folks.

I'm trying to convert the out of tree bt869 driver in 2.6.21 from using a semaphore to using a mutex. I followed the guidelines at http://lwn.net/Articles/164802/ and used http://lkml.org/lkml/2006/1/13/127 aa an example.
The original driver source can be found at http://sarijopen/~caligula/kernel/patches/bt869-2.6.21.patch

---------------

At first I only changed "struct semaphore update_lock" into "struct mutex_debug update_lock;"

However gcc gave me a
drivers/i2c/chips/bt869.c:63: error: field `update_lock' has incomplete type
make[1]: *** [drivers/i2c/chips/bt869.o] Error 1
make: *** [drivers/i2c/chips/bt869.ko] Error 2

----------------
Then I did a full conversion:

--- drivers/i2c/chips/bt869.c--orig 2007-07-12 07:14:18.000000000 +0200
+++ drivers/i2c/chips/bt869.c 2007-07-12 10:54:04.000000000 +0200
@@ -31,6 +31,7 @@
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/i2c.h>
+#include <linux/mutex.h>

/* Addresses to scan */
/* found only at 0x44 or 0x45 */
@@ -59,7 +60,7 @@ struct bt869_data {
struct i2c_client client;
int sysctl_id;

- struct semaphore update_lock;
+ struct mutex_debug update_lock;
char valid; /* !=0 if following fields are valid */
unsigned long last_updated; /* In jiffies */

@@ -547,7 +548,7 @@ int bt869_detect(struct i2c_adapter *ada

//new_client->id = bt869_id++;
data->valid = 0;
- init_MUTEX(&data->update_lock);
+ mutex_init(&data->update_lock);

/* Tell the I2C layer a new client has arrived */
if ((err = i2c_attach_client(new_client)))
@@ -650,7 +651,7 @@ static struct bt869_data *bt869_update_c
struct i2c_client *client = to_i2c_client(dev);
struct bt869_data *data = i2c_get_clientdata(client);

- down(&data->update_lock);
+ mutex_lock(&data->update_lock);

if ((jiffies - data->last_updated > HZ + HZ / 2) ||
(jiffies < data->last_updated) || !data->valid) {
@@ -732,7 +733,7 @@ static struct bt869_data *bt869_update_c
data->last_updated = jiffies;
data->valid = 1;
}
- up(&data->update_lock);
+ mutex_unlock(&data->update_lock);

return data;
}


Still gcc gives me a :
drivers/i2c/chips/bt869.c:63: error: field `update_lock' has incomplete type
make[1]: *** [drivers/i2c/chips/bt869.o] Error 1
make: *** [drivers/i2c/chips/bt869.ko] Error 2


I must miss something really really obvious, but I really can't find it.
Can someone guide me to the Right Way (TM) to convert this semaphore?
Thanks

Martijn Uffing



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