according to http://lwn.net/Articles/167034/ binary semaphores (which
aren't given in interrupt context or locked/unlocked in different
process contexts) should be converted to the new mutex API.
this patch converts the semaphore used by the Smart Battery System
ACPI interface driver to a mutex.
please let me know your comments if i misinterpreted the article or if
you see something wrong in the patch
--
Smart Battery System ACPI driver: convert binary semaphore to mutex
Signed-off-by: Matthias Kaehlcke <[email protected]>
--
diff --git a/drivers/acpi/sbs.c b/drivers/acpi/sbs.c
index 59640d9..7e90132 100644
--- a/drivers/acpi/sbs.c
+++ b/drivers/acpi/sbs.c
@@ -32,6 +32,7 @@
#include <linux/acpi.h>
#include <linux/i2c.h>
#include <linux/delay.h>
+#include <linux/mutex.h>
#include "i2c_ec.h"
@@ -83,7 +84,7 @@ MODULE_AUTHOR("Rich Townsend");
MODULE_DESCRIPTION("Smart Battery System ACPI interface driver");
MODULE_LICENSE("GPL");
-static struct semaphore sbs_sem;
+static DEFINE_MUTEX(sbs_mutex);
#define UPDATE_MODE QUEUE_UPDATE_MODE
/* REQUEST_UPDATE_MODE QUEUE_UPDATE_MODE */
@@ -930,7 +931,7 @@ static int acpi_battery_read_info(struct seq_file *seq, void *offset)
return -ENODEV;
}
- down(&sbs_sem);
+ mutex_lock(&sbs_mutex);
if (update_mode == REQUEST_UPDATE_MODE) {
result = acpi_sbs_update_run(battery->sbs, DATA_TYPE_INFO);
@@ -984,7 +985,7 @@ static int acpi_battery_read_info(struct seq_file *seq, void *offset)
end:
- up(&sbs_sem);
+ mutex_unlock(&sbs_mutex);
return result;
}
@@ -1005,7 +1006,7 @@ static int acpi_battery_read_state(struct seq_file *seq, void *offset)
return -ENODEV;
}
- down(&sbs_sem);
+ mutex_lock(&sbs_mutex);
if (update_mode == REQUEST_UPDATE_MODE) {
result = acpi_sbs_update_run(battery->sbs, DATA_TYPE_STATE);
@@ -1061,7 +1062,7 @@ static int acpi_battery_read_state(struct seq_file *seq, void *offset)
end:
- up(&sbs_sem);
+ mutex_unlock(&sbs_mutex);
return result;
}
@@ -1081,7 +1082,7 @@ static int acpi_battery_read_alarm(struct seq_file *seq, void *offset)
return -ENODEV;
}
- down(&sbs_sem);
+ mutex_lock(&sbs_mutex);
if (update_mode == REQUEST_UPDATE_MODE) {
result = acpi_sbs_update_run(battery->sbs, DATA_TYPE_ALARM);
@@ -1113,7 +1114,7 @@ static int acpi_battery_read_alarm(struct seq_file *seq, void *offset)
end:
- up(&sbs_sem);
+ mutex_unlock(&sbs_mutex);
return result;
}
@@ -1131,7 +1132,7 @@ acpi_battery_write_alarm(struct file *file, const char __user * buffer,
return -ENODEV;
}
- down(&sbs_sem);
+ mutex_lock(&sbs_mutex);
if (!acpi_battery_is_present(battery)) {
result = -ENODEV;
@@ -1169,7 +1170,7 @@ acpi_battery_write_alarm(struct file *file, const char __user * buffer,
}
end:
- up(&sbs_sem);
+ mutex_unlock(&sbs_mutex);
if (result) {
return result;
@@ -1221,7 +1222,7 @@ static int acpi_ac_read_state(struct seq_file *seq, void *offset)
return -ENODEV;
}
- down(&sbs_sem);
+ mutex_lock(&sbs_mutex);
if (update_mode == REQUEST_UPDATE_MODE) {
result = acpi_sbs_update_run(sbs, DATA_TYPE_AC_STATE);
@@ -1234,7 +1235,7 @@ static int acpi_ac_read_state(struct seq_file *seq, void *offset)
seq_printf(seq, "state: %s\n",
sbs->ac_present ? "on-line" : "off-line");
- up(&sbs_sem);
+ mutex_unlock(&sbs_mutex);
return 0;
}
@@ -1719,8 +1720,6 @@ static int __init acpi_sbs_init(void)
if (acpi_disabled)
return -ENODEV;
- init_MUTEX(&sbs_sem);
-
if (capacity_mode != DEF_CAPACITY_UNIT
&& capacity_mode != MAH_CAPACITY_UNIT
&& capacity_mode != MWH_CAPACITY_UNIT) {
--
Matthias Kaehlcke
Linux Application Developer
Barcelona
Anyone who has never made a mistake has never tried anything new
(Albert Einstein)
.''`.
using free software / Debian GNU/Linux | http://debian.org : :' :
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