From 6629dcff19470a894ce294d0adb9cbab94ee1fb9 Mon Sep 17 00:00:00 2001 From: Jean Delvare Date: Tue, 4 May 2010 11:09:28 +0200 Subject: [PATCH] i2c-core: Use per-adapter userspace device lists 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 Acked-by: Michael Lawnick --- drivers/i2c/i2c-core.c | 34 ++++++++++++++++++---------------- include/linux/i2c.h | 2 ++ 2 files changed, 20 insertions(+), 16 deletions(-) diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index 5105126..c2258a5 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c @@ -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, struct device_attribute *attr, 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 *dev, struct device_attribute *attr, /* 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 *dev, struct device_attribute *attr, 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 i2c_adapter *adap) } 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 *adap) 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. */ diff --git a/include/linux/i2c.h b/include/linux/i2c.h index 0a5da63..6ed1d59 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -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) -- 2.7.4