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i2c: Limit core locking to the necessary sections

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The i2c-core code tends to hold the core lock for longer than it
should. Limit locking to the necessary sections for both performance
and clarity. This is also a requirement to support I2C multiplexers in
the future.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Tested-by: Rodolfo Giometti <giometti@linux.it>
Cc: David Brownell <dbrownell@users.sourceforge.net>
This commit is contained in:
Jean Delvare 2009-06-19 16:58:19 +02:00
parent e549c2b54d
commit 35fc37f818
1 changed files with 28 additions and 23 deletions
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51
drivers/i2c/i2c-core.c
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@ -38,6 +38,9 @@
#include "i2c-core.h"
/* core_lock protects i2c_adapter_idr, and guarantees
that device detection, deletion of detected devices, and attach_adapter
and detach_adapter calls are serialized */
static DEFINE_MUTEX(core_lock);
static DEFINE_IDR(i2c_adapter_idr);
@ -418,13 +421,13 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
int res = 0, dummy;
/* Can't register until after driver model init */
if (unlikely(WARN_ON(!i2c_bus_type.p)))
return -EAGAIN;
if (unlikely(WARN_ON(!i2c_bus_type.p))) {
res = -EAGAIN;
goto out_list;
}
mutex_init(&adap->bus_lock);
mutex_lock(&core_lock);
/* Set default timeout to 1 second if not already set */
if (adap->timeout == 0)
adap->timeout = HZ;
@ -443,16 +446,18 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
i2c_scan_static_board_info(adap);
/* Notify drivers */
mutex_lock(&core_lock);
dummy = bus_for_each_drv(&i2c_bus_type, NULL, adap,
i2c_do_add_adapter);
out_unlock:
mutex_unlock(&core_lock);
return res;
return 0;
out_list:
mutex_lock(&core_lock);
idr_remove(&i2c_adapter_idr, adap->nr);
goto out_unlock;
mutex_unlock(&core_lock);
return res;
}
/**
@ -590,22 +595,25 @@ static int __unregister_client(struct device *dev, void *dummy)
int i2c_del_adapter(struct i2c_adapter *adap)
{
int res = 0;
mutex_lock(&core_lock);
struct i2c_adapter *found;
/* First make sure that this adapter was ever added */
if (idr_find(&i2c_adapter_idr, adap->nr) != adap) {
mutex_lock(&core_lock);
found = idr_find(&i2c_adapter_idr, adap->nr);
mutex_unlock(&core_lock);
if (found != adap) {
pr_debug("i2c-core: attempting to delete unregistered "
"adapter [%s]\n", adap->name);
res = -EINVAL;
goto out_unlock;
return -EINVAL;
}
/* Tell drivers about this removal */
mutex_lock(&core_lock);
res = bus_for_each_drv(&i2c_bus_type, NULL, adap,
i2c_do_del_adapter);
mutex_unlock(&core_lock);
if (res)
goto out_unlock;
return res;
/* Detach any active clients. This can't fail, thus we do not
checking the returned value. */
@ -619,7 +627,9 @@ int i2c_del_adapter(struct i2c_adapter *adap)
wait_for_completion(&adap->dev_released);
/* free bus id */
mutex_lock(&core_lock);
idr_remove(&i2c_adapter_idr, adap->nr);
mutex_unlock(&core_lock);
dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);
@ -627,9 +637,7 @@ int i2c_del_adapter(struct i2c_adapter *adap)
added again */
memset(&adap->dev, 0, sizeof(adap->dev));
out_unlock:
mutex_unlock(&core_lock);
return res;
return 0;
}
EXPORT_SYMBOL(i2c_del_adapter);
@ -674,16 +682,15 @@ int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
if (res)
return res;
mutex_lock(&core_lock);
pr_debug("i2c-core: driver [%s] registered\n", driver->driver.name);
INIT_LIST_HEAD(&driver->clients);
/* Walk the adapters that are already present */
mutex_lock(&core_lock);
class_for_each_device(&i2c_adapter_class, NULL, driver,
__attach_adapter);
mutex_unlock(&core_lock);
return 0;
}
EXPORT_SYMBOL(i2c_register_driver);
@ -721,14 +728,12 @@ static int __detach_adapter(struct device *dev, void *data)
void i2c_del_driver(struct i2c_driver *driver)
{
mutex_lock(&core_lock);
class_for_each_device(&i2c_adapter_class, NULL, driver,
__detach_adapter);
mutex_unlock(&core_lock);
driver_unregister(&driver->driver);
pr_debug("i2c-core: driver [%s] unregistered\n", driver->driver.name);
mutex_unlock(&core_lock);
}
EXPORT_SYMBOL(i2c_del_driver);