Using a single list for all userspace devices leads to a dead lock
on multiplexed buses in some circumstances (mux chip instantiated
from userspace). This is solved by using a separate list for each
bus segment.
Signed-off-by: Jean Delvare <khali@xxxxxxxxxxxx>
Acked-by: Michael Lawnick <ml.lawnick@xxxxxx>
---
drivers/i2c/i2c-core.c | 34 ++++++++++++++++++----------------
include/linux/i2c.h | 2 ++
2 files changed, 20 insertions(+), 16 deletions(-)
--- linux-2.6.34-rc5.orig/drivers/i2c/i2c-core.c 2010-04-23 18:45:23.000000000 +0200
+++ linux-2.6.34-rc5/drivers/i2c/i2c-core.c 2010-04-24 13:02:24.000000000 +0200
@@ -40,12 +40,11 @@
#include "i2c-core.h"
-/* core_lock protects i2c_adapter_idr, userspace_devices, and guarantees
+/* 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);
-static LIST_HEAD(userspace_devices);
static struct device_type i2c_client_type;
static int i2c_check_addr(struct i2c_adapter *adapter, int addr);
@@ -542,9 +541,9 @@ i2c_sysfs_new_device(struct device *dev,
return -EEXIST;
/* Keep track of the added device */
- mutex_lock(&core_lock);
- list_add_tail(&client->detected, &userspace_devices);
- mutex_unlock(&core_lock);
+ i2c_lock_adapter(adap);
+ list_add_tail(&client->detected, &adap->userspace_clients);
+ i2c_unlock_adapter(adap);
dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",
info.type, info.addr);
@@ -583,9 +582,10 @@ i2c_sysfs_delete_device(struct device *d
/* Make sure the device was added through sysfs */
res = -ENOENT;
- mutex_lock(&core_lock);
- list_for_each_entry_safe(client, next, &userspace_devices, detected) {
- if (client->addr == addr && client->adapter == adap) {
+ i2c_lock_adapter(adap);
+ list_for_each_entry_safe(client, next, &adap->userspace_clients,
+ detected) {
+ if (client->addr == addr) {
dev_info(dev, "%s: Deleting device %s at 0x%02hx\n",
"delete_device", client->name, client->addr);
@@ -595,7 +595,7 @@ i2c_sysfs_delete_device(struct device *d
break;
}
}
- mutex_unlock(&core_lock);
+ i2c_unlock_adapter(adap);
if (res < 0)
dev_err(dev, "%s: Can't find device in list\n",
@@ -677,6 +677,7 @@ static int i2c_register_adapter(struct i
}
rt_mutex_init(&adap->bus_lock);
+ INIT_LIST_HEAD(&adap->userspace_clients);
/* Set default timeout to 1 second if not already set */
if (adap->timeout == 0)
@@ -879,14 +880,15 @@ int i2c_del_adapter(struct i2c_adapter *
return res;
/* Remove devices instantiated from sysfs */
- list_for_each_entry_safe(client, next, &userspace_devices, detected) {
- if (client->adapter == adap) {
- dev_dbg(&adap->dev, "Removing %s at 0x%x\n",
- client->name, client->addr);
- list_del(&client->detected);
- i2c_unregister_device(client);
- }
+ i2c_lock_adapter(adap);
+ list_for_each_entry_safe(client, next, &adap->userspace_clients,
+ detected) {
+ dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
+ client->addr);
+ list_del(&client->detected);
+ i2c_unregister_device(client);
}
+ i2c_unlock_adapter(adap);
/* Detach any active clients. This can't fail, thus we do not
checking the returned value. */
--- linux-2.6.34-rc5.orig/include/linux/i2c.h 2010-04-23 18:45:22.000000000 +0200
+++ linux-2.6.34-rc5/include/linux/i2c.h 2010-04-24 13:02:24.000000000 +0200
@@ -355,6 +355,8 @@ struct i2c_adapter {
int nr;
char name[48];
struct completion dev_released;
+
+ struct list_head userspace_clients;
};
#define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)
--
Jean Delvare
--
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