Moving userspace-instantiated clients to separate lists wasn't nearly
enough to avoid deadlocks in multiplexed bus cases. We also want to
have a dedicated mutex to protect each list.
Signed-off-by: Jean Delvare <khali@xxxxxxxxxxxx>
Cc: Michael Lawnick <ml.lawnick@xxxxxx>
---
Michael, this should solve any deadlock issue related to userspace
devices we've been discussing lately. I should probably have done this
from the beginning. This also has the benefit of making your own patch
slightly smaller - I'll update it myself.
drivers/i2c/i2c-core.c | 13 +++++++------
include/linux/i2c.h | 1 +
2 files changed, 8 insertions(+), 6 deletions(-)
--- linux-2.6.35-rc5.orig/drivers/i2c/i2c-core.c 2010-07-19 09:11:51.000000000 +0200
+++ linux-2.6.35-rc5/drivers/i2c/i2c-core.c 2010-07-20 13:08:51.000000000 +0200
@@ -656,9 +656,9 @@ i2c_sysfs_new_device(struct device *dev,
return -EINVAL;
/* Keep track of the added device */
- i2c_lock_adapter(adap);
+ mutex_lock(&adap->userspace_clients_lock);
list_add_tail(&client->detected, &adap->userspace_clients);
- i2c_unlock_adapter(adap);
+ mutex_unlock(&adap->userspace_clients_lock);
dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",
info.type, info.addr);
@@ -697,7 +697,7 @@ i2c_sysfs_delete_device(struct device *d
/* Make sure the device was added through sysfs */
res = -ENOENT;
- i2c_lock_adapter(adap);
+ mutex_lock(&adap->userspace_clients_lock);
list_for_each_entry_safe(client, next, &adap->userspace_clients,
detected) {
if (client->addr == addr) {
@@ -710,7 +710,7 @@ i2c_sysfs_delete_device(struct device *d
break;
}
}
- i2c_unlock_adapter(adap);
+ mutex_unlock(&adap->userspace_clients_lock);
if (res < 0)
dev_err(dev, "%s: Can't find device in list\n",
@@ -792,6 +792,7 @@ static int i2c_register_adapter(struct i
}
rt_mutex_init(&adap->bus_lock);
+ mutex_init(&adap->userspace_clients_lock);
INIT_LIST_HEAD(&adap->userspace_clients);
/* Set default timeout to 1 second if not already set */
@@ -994,7 +995,7 @@ int i2c_del_adapter(struct i2c_adapter *
return res;
/* Remove devices instantiated from sysfs */
- i2c_lock_adapter(adap);
+ mutex_lock(&adap->userspace_clients_lock);
list_for_each_entry_safe(client, next, &adap->userspace_clients,
detected) {
dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
@@ -1002,7 +1003,7 @@ int i2c_del_adapter(struct i2c_adapter *
list_del(&client->detected);
i2c_unregister_device(client);
}
- i2c_unlock_adapter(adap);
+ mutex_unlock(&adap->userspace_clients_lock);
/* Detach any active clients. This can't fail, thus we do not
checking the returned value. */
--- linux-2.6.35-rc5.orig/include/linux/i2c.h 2010-07-19 09:11:50.000000000 +0200
+++ linux-2.6.35-rc5/include/linux/i2c.h 2010-07-20 12:58:08.000000000 +0200
@@ -366,6 +366,7 @@ struct i2c_adapter {
char name[48];
struct completion dev_released;
+ struct mutex userspace_clients_lock;
struct list_head userspace_clients;
};
#define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)
--
Jean Delvare
--
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