From foo@baz Tue Apr 9 12:12:43 2002 To: Greg KH Date: 21 Mar 2005 10:41:04 -08:00 From: mochel@digitalimplant.org Subject: [driver core] 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: Patrick Mochel Signed-off-by: Greg Kroah-Hartman Index: linux-2.6.12-rc2/drivers/base/bus.c =================================================================== --- linux-2.6.12-rc2.orig/drivers/base/bus.c 2005-04-05 14:30:57.000000000 -0700 +++ linux-2.6.12-rc2/drivers/base/bus.c 2005-04-05 14:33:43.000000000 -0700 @@ -283,18 +283,22 @@ */ int driver_probe_device(struct device_driver * drv, struct device * dev) { + int error = 0; + if (drv->bus->match && !drv->bus->match(dev, drv)) return -ENODEV; + down(&dev->sem); dev->driver = drv; if (drv->probe) { - int error = drv->probe(dev); + error = drv->probe(dev); if (error) { dev->driver = NULL; + up(&dev->sem); return error; } } - + up(&dev->sem); device_bind_driver(dev); return 0; } @@ -385,7 +389,10 @@ 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) { sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj)); sysfs_remove_link(&dev->kobj, "driver"); @@ -395,6 +402,7 @@ drv->remove(dev); dev->driver = NULL; } + up(&dev->sem); } Index: linux-2.6.12-rc2/drivers/base/core.c =================================================================== --- linux-2.6.12-rc2.orig/drivers/base/core.c 2005-04-05 14:33:40.000000000 -0700 +++ linux-2.6.12-rc2/drivers/base/core.c 2005-04-05 14:33:43.000000000 -0700 @@ -215,6 +215,7 @@ INIT_LIST_HEAD(&dev->driver_list); INIT_LIST_HEAD(&dev->bus_list); INIT_LIST_HEAD(&dev->dma_pools); + init_MUTEX(&dev->sem); } /** Index: linux-2.6.12-rc2/drivers/base/power/resume.c =================================================================== --- linux-2.6.12-rc2.orig/drivers/base/power/resume.c 2005-04-05 14:30:57.000000000 -0700 +++ linux-2.6.12-rc2/drivers/base/power/resume.c 2005-04-05 14:33:43.000000000 -0700 @@ -22,9 +22,13 @@ int resume_device(struct device * dev) { + int error = 0; + + down(&dev->sem); if (dev->bus && dev->bus->resume) - return dev->bus->resume(dev); - return 0; + error = dev->bus->resume(dev); + up(&dev->sem); + return error; } Index: linux-2.6.12-rc2/drivers/base/power/suspend.c =================================================================== --- linux-2.6.12-rc2.orig/drivers/base/power/suspend.c 2005-04-05 14:30:57.000000000 -0700 +++ linux-2.6.12-rc2/drivers/base/power/suspend.c 2005-04-05 14:33:43.000000000 -0700 @@ -41,11 +41,11 @@ dev_dbg(dev, "suspending\n"); + down(&dev->sem); dev->power.prev_state = dev->power.power_state; - if (dev->bus && dev->bus->suspend && !dev->power.power_state) error = dev->bus->suspend(dev, state); - + up(&dev->sem); return error; } Index: linux-2.6.12-rc2/include/linux/device.h =================================================================== --- linux-2.6.12-rc2.orig/include/linux/device.h 2005-04-05 14:33:38.000000000 -0700 +++ linux-2.6.12-rc2/include/linux/device.h 2005-04-05 14:33:43.000000000 -0700 @@ -264,6 +264,10 @@ struct kobject kobj; 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 device_driver *driver; /* which driver has allocated this device */