Commit af70316a authored by mochel@digitalimplant.org's avatar mochel@digitalimplant.org Committed by Greg Kroah-Hartman

[PATCH] Add a semaphore to struct device to synchronize calls to its driver.

This adds a per-device semaphore that is taken before every call from the core to a
driver method. This prevents e.g. simultaneous calls to the ->suspend() or ->resume()
and ->probe() or ->release(), potentially saving a whole lot of headaches.

It also moves us a step closer to removing the bus rwsem, since it protects the fields
in struct device that are modified by the core.
Signed-off-by: default avatarPatrick Mochel <mochel@digitalimplant.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent eb51b650
...@@ -283,18 +283,22 @@ void device_bind_driver(struct device * dev) ...@@ -283,18 +283,22 @@ void device_bind_driver(struct device * dev)
*/ */
int driver_probe_device(struct device_driver * drv, struct device * dev) int driver_probe_device(struct device_driver * drv, struct device * dev)
{ {
int error = 0;
if (drv->bus->match && !drv->bus->match(dev, drv)) if (drv->bus->match && !drv->bus->match(dev, drv))
return -ENODEV; return -ENODEV;
down(&dev->sem);
dev->driver = drv; dev->driver = drv;
if (drv->probe) { if (drv->probe) {
int error = drv->probe(dev); error = drv->probe(dev);
if (error) { if (error) {
dev->driver = NULL; dev->driver = NULL;
up(&dev->sem);
return error; return error;
} }
} }
up(&dev->sem);
device_bind_driver(dev); device_bind_driver(dev);
return 0; return 0;
} }
...@@ -385,7 +389,10 @@ void driver_attach(struct device_driver * drv) ...@@ -385,7 +389,10 @@ void driver_attach(struct device_driver * drv)
void device_release_driver(struct device * dev) void device_release_driver(struct device * dev)
{ {
struct device_driver * drv = dev->driver; struct device_driver * drv;
down(&dev->sem);
drv = dev->driver;
if (drv) { if (drv) {
sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj)); sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj));
sysfs_remove_link(&dev->kobj, "driver"); sysfs_remove_link(&dev->kobj, "driver");
...@@ -394,6 +401,7 @@ void device_release_driver(struct device * dev) ...@@ -394,6 +401,7 @@ void device_release_driver(struct device * dev)
drv->remove(dev); drv->remove(dev);
dev->driver = NULL; dev->driver = NULL;
} }
up(&dev->sem);
} }
......
...@@ -212,6 +212,7 @@ void device_initialize(struct device *dev) ...@@ -212,6 +212,7 @@ void device_initialize(struct device *dev)
INIT_LIST_HEAD(&dev->driver_list); INIT_LIST_HEAD(&dev->driver_list);
INIT_LIST_HEAD(&dev->bus_list); INIT_LIST_HEAD(&dev->bus_list);
INIT_LIST_HEAD(&dev->dma_pools); INIT_LIST_HEAD(&dev->dma_pools);
init_MUTEX(&dev->sem);
} }
/** /**
......
...@@ -22,6 +22,9 @@ extern int sysdev_resume(void); ...@@ -22,6 +22,9 @@ extern int sysdev_resume(void);
int resume_device(struct device * dev) int resume_device(struct device * dev)
{ {
int error = 0;
down(&dev->sem);
if (dev->power.pm_parent if (dev->power.pm_parent
&& dev->power.pm_parent->power.power_state) { && dev->power.pm_parent->power.power_state) {
dev_err(dev, "PM: resume from %d, parent %s still %d\n", dev_err(dev, "PM: resume from %d, parent %s still %d\n",
...@@ -31,9 +34,10 @@ int resume_device(struct device * dev) ...@@ -31,9 +34,10 @@ int resume_device(struct device * dev)
} }
if (dev->bus && dev->bus->resume) { if (dev->bus && dev->bus->resume) {
dev_dbg(dev,"resuming\n"); dev_dbg(dev,"resuming\n");
return dev->bus->resume(dev); error = dev->bus->resume(dev);
} }
return 0; up(&dev->sem);
return error;
} }
......
...@@ -39,6 +39,7 @@ int suspend_device(struct device * dev, pm_message_t state) ...@@ -39,6 +39,7 @@ int suspend_device(struct device * dev, pm_message_t state)
{ {
int error = 0; int error = 0;
down(&dev->sem);
if (dev->power.power_state) { if (dev->power.power_state) {
dev_dbg(dev, "PM: suspend %d-->%d\n", dev_dbg(dev, "PM: suspend %d-->%d\n",
dev->power.power_state, state); dev->power.power_state, state);
...@@ -58,7 +59,7 @@ int suspend_device(struct device * dev, pm_message_t state) ...@@ -58,7 +59,7 @@ int suspend_device(struct device * dev, pm_message_t state)
dev_dbg(dev, "suspending\n"); dev_dbg(dev, "suspending\n");
error = dev->bus->suspend(dev, state); error = dev->bus->suspend(dev, state);
} }
up(&dev->sem);
return error; return error;
} }
......
...@@ -264,6 +264,10 @@ struct device { ...@@ -264,6 +264,10 @@ struct device {
struct kobject kobj; struct kobject kobj;
char bus_id[BUS_ID_SIZE]; /* position on parent bus */ char bus_id[BUS_ID_SIZE]; /* position on parent bus */
struct semaphore sem; /* semaphore to synchronize calls to
* its driver.
*/
struct bus_type * bus; /* type of bus device is on */ struct bus_type * bus; /* type of bus device is on */
struct device_driver *driver; /* which driver has allocated this struct device_driver *driver; /* which driver has allocated this
device */ device */
......
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