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