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Commit 2ec18910 authored by Christoph Hellwig's avatar Christoph Hellwig
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[PATCH] i2c-core locking updates 

The old adap_lock and driver_lock could deadlock and there was a bunch
of stuff that was horribly racy.  The new locking scheme is from
lm_sensors CVS but I had to fix quite a few bugs to make this work.
parent a712ff9f
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Showing with 113 additions and 122 deletions
drivers/i2c/i2c-core.c
View file @ 2ec18910
......@@ -21,49 +21,24 @@
All SMBus-related things are written by Frodo Looijaard <frodol@dds.nl>
SMBus 2.0 support by Mark Studebaker <mdsxyz123@yahoo.com> */
/* $Id: i2c-core.c,v 1.89 2002/11/03 16:47:16 mds Exp $ */
/* $Id: i2c-core.c,v 1.95 2003/01/22 05:25:08 kmalkki Exp $ */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/proc_fs.h>
#include <linux/config.h>
#include <linux/i2c.h>
/* ----- compatibility stuff ----------------------------------------------- */
#include <linux/version.h>
#include <linux/init.h>
#include <asm/uaccess.h>
/* ----- global defines ---------------------------------------------------- */
/* exclusive access to the bus */
#define I2C_LOCK(adap) down(&adap->lock)
#define I2C_UNLOCK(adap) up(&adap->lock)
#define ADAP_LOCK() down(&adap_lock)
#define ADAP_UNLOCK() up(&adap_lock)
#define DRV_LOCK() down(&driver_lock)
#define DRV_UNLOCK() up(&driver_lock)
#define DEB(x) if (i2c_debug>=1) x;
#define DEB2(x) if (i2c_debug>=2) x;
/* ----- global variables -------------------------------------------------- */
/**** lock for writing to global variables: the adapter & driver list */
static DECLARE_MUTEX(adap_lock);
static DECLARE_MUTEX(driver_lock);
/**** adapter list */
static struct i2c_adapter *adapters[I2C_ADAP_MAX];
/**** drivers list */
static struct i2c_driver *drivers[I2C_DRIVER_MAX];
static DECLARE_MUTEX(core_lists);
/**** debug level */
static int i2c_debug;
......@@ -89,9 +64,9 @@ static void i2cproc_remove(int bus);
*/
int i2c_add_adapter(struct i2c_adapter *adap)
{
int i,j,res;
int res = 0, i, j;
ADAP_LOCK();
down(&core_lists);
for (i = 0; i < I2C_ADAP_MAX; i++)
if (NULL == adapters[i])
break;
......@@ -99,45 +74,41 @@ int i2c_add_adapter(struct i2c_adapter *adap)
printk(KERN_WARNING
" i2c-core.o: register_adapter(%s) - enlarge I2C_ADAP_MAX.\n",
adap->name);
goto fail;
res = -ENOMEM;
goto out_unlock;
}
adapters[i] = adap;
ADAP_UNLOCK();
/* init data types */
init_MUTEX(&adap->lock);
res = i2cproc_register(adap, i);
if (res)
return res;
goto out_unlock;
adapters[i] = adap;
init_MUTEX(&adap->bus);
init_MUTEX(&adap->list);
/* inform drivers of new adapters */
DRV_LOCK();
for (j=0;j<I2C_DRIVER_MAX;j++)
if (drivers[j]!=NULL &&
(drivers[j]->flags&(I2C_DF_NOTIFY|I2C_DF_DUMMY)))
/* We ignore the return code; if it fails, too bad */
drivers[j]->attach_adapter(adap);
DRV_UNLOCK();
up(&core_lists);
DEB(printk(KERN_DEBUG "i2c-core.o: adapter %s registered as adapter %d.\n",
adap->name,i));
return 0;
fail:
ADAP_UNLOCK();
return -ENOMEM;
out_unlock:
up(&core_lists);
return res;;
}
int i2c_del_adapter(struct i2c_adapter *adap)
{
int i,j,res;
ADAP_LOCK();
int res = 0, i, j;
down(&core_lists);
for (i = 0; i < I2C_ADAP_MAX; i++)
if (adap == adapters[i])
break;
......@@ -145,7 +116,7 @@ int i2c_del_adapter(struct i2c_adapter *adap)
printk( KERN_WARNING "i2c-core.o: unregister_adapter adap [%s] not found.\n",
adap->name);
res = -ENODEV;
goto ERROR0;
goto out_unlock;
}
/* DUMMY drivers do not register their clients, so we have to
......@@ -153,23 +124,20 @@ int i2c_del_adapter(struct i2c_adapter *adap)
* *detach* it! Of course, each dummy driver should know about
* this or hell will break loose...
*/
DRV_LOCK();
for (j = 0; j < I2C_DRIVER_MAX; j++)
if (drivers[j] && (drivers[j]->flags & I2C_DF_DUMMY))
if ((res = drivers[j]->attach_adapter(adap))) {
printk(KERN_WARNING "i2c-core.o: can't detach adapter %s "
"while detaching driver %s: driver not "
"detached!",adap->name,drivers[j]->name);
goto ERROR1;
goto out_unlock;
}
DRV_UNLOCK();
/* detach any active clients. This must be done first, because
* it can fail; in which case we give upp. */
for (j=0;j<I2C_CLIENT_MAX;j++) {
struct i2c_client *client = adap->clients[j];
if (client!=NULL)
if (client!=NULL) {
/* detaching devices is unconditional of the set notify
* flag, as _all_ clients that reside on the adapter
* must be deleted, as this would cause invalid states.
......@@ -179,23 +147,19 @@ int i2c_del_adapter(struct i2c_adapter *adap)
"unregistered, because client at "
"address %02x can't be detached. ",
adap->name, client->addr);
goto ERROR0;
goto out_unlock;
}
}
}
i2cproc_remove(i);
adapters[i] = NULL;
ADAP_UNLOCK();
DEB(printk(KERN_DEBUG "i2c-core.o: adapter unregistered: %s\n",adap->name));
return 0;
ERROR0:
ADAP_UNLOCK();
return res;
ERROR1:
DRV_UNLOCK();
out_unlock:
up(&core_lists);
return res;
}
......@@ -208,8 +172,9 @@ int i2c_del_adapter(struct i2c_adapter *adap)
int i2c_add_driver(struct i2c_driver *driver)
{
int i;
DRV_LOCK();
int res = 0, i;
down(&core_lists);
for (i = 0; i < I2C_DRIVER_MAX; i++)
if (NULL == drivers[i])
break;
......@@ -218,35 +183,34 @@ int i2c_add_driver(struct i2c_driver *driver)
" i2c-core.o: register_driver(%s) "
"- enlarge I2C_DRIVER_MAX.\n",
driver->name);
DRV_UNLOCK();
return -ENOMEM;
res = -ENOMEM;
goto out_unlock;
}
drivers[i] = driver;
DRV_UNLOCK(); /* driver was successfully added */
DEB(printk(KERN_DEBUG "i2c-core.o: driver %s registered.\n",driver->name));
ADAP_LOCK();
/* now look for instances of driver on our adapters
*/
if (driver->flags& (I2C_DF_NOTIFY|I2C_DF_DUMMY)) {
for (i=0;i<I2C_ADAP_MAX;i++)
for (i=0;i<I2C_ADAP_MAX;i++) {
if (adapters[i]!=NULL)
/* Ignore errors */
driver->attach_adapter(adapters[i]);
}
}
ADAP_UNLOCK();
return 0;
out_unlock:
up(&core_lists);
return res;
}
int i2c_del_driver(struct i2c_driver *driver)
{
int i,j,k,res;
int res = 0, i, j, k;
DRV_LOCK();
down(&core_lists);
for (i = 0; i < I2C_DRIVER_MAX; i++)
if (driver == drivers[i])
break;
......@@ -254,19 +218,20 @@ int i2c_del_driver(struct i2c_driver *driver)
printk(KERN_WARNING " i2c-core.o: unregister_driver: "
"[%s] not found\n",
driver->name);
DRV_UNLOCK();
return -ENODEV;
res = -ENODEV;
goto out_unlock;
}
/* Have a look at each adapter, if clients of this driver are still
* attached. If so, detach them to be able to kill the driver
* afterwards.
*/
DEB2(printk(KERN_DEBUG "i2c-core.o: unregister_driver - looking for clients.\n"));
/* removing clients does not depend on the notify flag, else
* invalid operation might (will!) result, when using stale client
* pointers.
*/
ADAP_LOCK(); /* should be moved inside the if statement... */
for (k=0;k<I2C_ADAP_MAX;k++) {
struct i2c_adapter *adap = adapters[k];
if (adap == NULL) /* skip empty entries. */
......@@ -285,8 +250,7 @@ int i2c_del_driver(struct i2c_driver *driver)
"not be detached properly; driver "
"not unloaded!",driver->name,
adap->name);
ADAP_UNLOCK();
return res;
goto out_unlock;
}
} else {
for (j=0;j<I2C_CLIENT_MAX;j++) {
......@@ -309,37 +273,51 @@ int i2c_del_driver(struct i2c_driver *driver)
driver->name,
client->addr,
adap->name);
ADAP_UNLOCK();
return res;
goto out_unlock;
}
}
}
}
}
ADAP_UNLOCK();
drivers[i] = NULL;
DRV_UNLOCK();
DEB(printk(KERN_DEBUG "i2c-core.o: driver unregistered: %s\n",driver->name));
out_unlock:
up(&core_lists);
return 0;
}
int i2c_check_addr (struct i2c_adapter *adapter, int addr)
static int __i2c_check_addr(struct i2c_adapter *adapter, int addr)
{
int i;
for (i = 0; i < I2C_CLIENT_MAX ; i++)
for (i = 0; i < I2C_CLIENT_MAX ; i++)
if (adapter->clients[i] && (adapter->clients[i]->addr == addr))
return -EBUSY;
return 0;
}
int i2c_check_addr(struct i2c_adapter *adapter, int addr)
{
int rval;
down(&adapter->list);
rval = __i2c_check_addr(adapter, addr);
up(&adapter->list);
return rval;
}
int i2c_attach_client(struct i2c_client *client)
{
struct i2c_adapter *adapter = client->adapter;
int i;
int res = -EBUSY, i;
if (i2c_check_addr(client->adapter,client->addr))
return -EBUSY;
down(&adapter->list);
if (__i2c_check_addr(client->adapter,client->addr))
goto out_unlock_list;
for (i = 0; i < I2C_CLIENT_MAX; i++)
if (NULL == adapter->clients[i])
......@@ -348,11 +326,12 @@ int i2c_attach_client(struct i2c_client *client)
printk(KERN_WARNING
" i2c-core.o: attach_client(%s) - enlarge I2C_CLIENT_MAX.\n",
client->name);
return -ENOMEM;
res = -ENOMEM;
goto out_unlock_list;
}
adapter->clients[i] = client;
adapter->client_count++;
up(&adapter->list);
if (adapter->client_register)
if (adapter->client_register(client))
......@@ -366,39 +345,45 @@ int i2c_attach_client(struct i2c_client *client)
client->usage_count = 0;
return 0;
out_unlock_list:
up(&adapter->list);
return res;
}
int i2c_detach_client(struct i2c_client *client)
{
struct i2c_adapter *adapter = client->adapter;
int i,res;
int res = 0, i;
if ((client->flags & I2C_CLIENT_ALLOW_USE) && (client->usage_count > 0))
return -EBUSY;
for (i = 0; i < I2C_CLIENT_MAX; i++)
if (adapter->client_unregister) {
res = adapter->client_unregister(client);
if (res) {
printk(KERN_ERR "i2c-core.o: client_unregister [%s] failed, "
"client not detached",client->name);
return res;
}
}
down(&adapter->list);
for (i = 0; i < I2C_CLIENT_MAX; i++) {
if (client == adapter->clients[i])
break;
}
if (I2C_CLIENT_MAX == i) {
printk(KERN_WARNING " i2c-core.o: unregister_client "
"[%s] not found\n",
client->name);
return -ENODEV;
}
if( (client->flags & I2C_CLIENT_ALLOW_USE) &&
(client->usage_count>0))
return -EBUSY;
if (adapter->client_unregister != NULL)
if ((res = adapter->client_unregister(client))) {
printk(KERN_ERR "i2c-core.o: client_unregister [%s] failed, "
"client not detached",client->name);
return res;
}
adapter->clients[i] = NULL;
adapter->client_count--;
} else
adapter->clients[i] = NULL;
up(&adapter->list);
DEB(printk(KERN_DEBUG "i2c-core.o: client [%s] unregistered.\n",client->name));
return 0;
}
......@@ -470,8 +455,12 @@ static int read_bus_i2c(char *buf, char **start, off_t offset,
{
int i;
int nr = 0;
/* Note that it is safe to write a `little' beyond len. Yes, really. */
for (i = 0; (i < I2C_ADAP_MAX) && (nr < len); i++)
/* Fuck you. Will convert this to seq_file later. --hch */
down(&core_lists);
for (i = 0; (i < I2C_ADAP_MAX) && (nr < len); i++) {
if (adapters[i]) {
nr += sprintf(buf+nr, "i2c-%d\t", i);
if (adapters[i]->algo->smbus_xfer) {
......@@ -487,6 +476,9 @@ static int read_bus_i2c(char *buf, char **start, off_t offset,
adapters[i]->name,
adapters[i]->algo->name);
}
}
up(&core_lists);
return nr;
}
......@@ -587,9 +579,8 @@ static void i2cproc_remove(int bus)
remove_proc_entry(name, proc_bus);
}
static int i2cproc_init(void)
static int __init i2cproc_init(void)
{
struct proc_dir_entry *proc_bus_i2c;
proc_bus_i2c = create_proc_entry("i2c",0,proc_bus);
......@@ -625,9 +616,9 @@ int i2c_transfer(struct i2c_adapter * adap, struct i2c_msg msgs[],int num)
DEB2(printk(KERN_DEBUG "i2c-core.o: master_xfer: %s with %d msgs.\n",
adap->name,num));
I2C_LOCK(adap);
down(&adap->bus);
ret = adap->algo->master_xfer(adap,msgs,num);
I2C_UNLOCK(adap);
up(&adap->bus);
return ret;
} else {
......@@ -652,9 +643,9 @@ int i2c_master_send(struct i2c_client *client,const char *buf ,int count)
DEB2(printk(KERN_DEBUG "i2c-core.o: master_send: writing %d bytes on %s.\n",
count,client->adapter->name));
I2C_LOCK(adap);
down(&adap->bus);
ret = adap->algo->master_xfer(adap,&msg,1);
I2C_UNLOCK(adap);
up(&adap->bus);
/* if everything went ok (i.e. 1 msg transmitted), return #bytes
* transmitted, else error code.
......@@ -682,9 +673,9 @@ int i2c_master_recv(struct i2c_client *client, char *buf ,int count)
DEB2(printk(KERN_DEBUG "i2c-core.o: master_recv: reading %d bytes on %s.\n",
count,client->adapter->name));
I2C_LOCK(adap);
down(&adap->bus);
ret = adap->algo->master_xfer(adap,&msg,1);
I2C_UNLOCK(adap);
up(&adap->bus);
DEB2(printk(KERN_DEBUG "i2c-core.o: master_recv: return:%d (count:%d, addr:0x%02x)\n",
ret, count, client->addr));
......@@ -1299,10 +1290,10 @@ s32 i2c_smbus_xfer(struct i2c_adapter * adapter, u16 addr, unsigned short flags,
}
if (adapter->algo->smbus_xfer) {
I2C_LOCK(adapter);
down(&adapter->bus);
res = adapter->algo->smbus_xfer(adapter,addr,flags,read_write,
command,size,data);
I2C_UNLOCK(adapter);
up(&adapter->bus);
} else
res = i2c_smbus_xfer_emulated(adapter,addr,flags,read_write,
command,size,data);
......
include/linux/i2c.h
View file @ 2ec18910
......@@ -220,11 +220,11 @@ struct i2c_adapter {
/* and can be set via the i2c_ioctl call */
/* data fields that are valid for all devices */
struct semaphore lock;
struct semaphore bus;
struct semaphore list;
unsigned int flags;/* flags specifying div. data */
struct i2c_client *clients[I2C_CLIENT_MAX];
int client_count;
int timeout;
int retries;
......
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