Messages in this thread Patch in this message | | | Subject | [PATCH] Add a semaphore to struct device to synchronize calls to its driver. | Date | Mon, 20 Jun 2005 15:59:24 -0700 | From | Greg KH <> |
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[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: Patrick Mochel <mochel@digitalimplant.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- commit af70316af182f4716cc5eec7e0d27fc731d164bd tree 22fa4732c8270db8fd3f681355cd83e4b8088847 parent eb51b65005737b777e0709683b061d5f82aefd97 author mochel@digitalimplant.org <mochel@digitalimplant.org> Mon, 21 Mar 2005 10:41:04 -0800 committer Greg Kroah-Hartman <gregkh@suse.de> Mon, 20 Jun 2005 15:15:12 -0700
drivers/base/bus.c | 14 +++++++++++--- drivers/base/core.c | 1 + drivers/base/power/resume.c | 8 ++++++-- drivers/base/power/suspend.c | 3 ++- include/linux/device.h | 4 ++++ 5 files changed, 24 insertions(+), 6 deletions(-)
diff --git a/drivers/base/bus.c b/drivers/base/bus.c --- a/drivers/base/bus.c +++ b/drivers/base/bus.c @@ -283,18 +283,22 @@ void device_bind_driver(struct device * */ 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 driver_attach(struct device_driver 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"); @@ -394,6 +401,7 @@ void device_release_driver(struct device drv->remove(dev); dev->driver = NULL; } + up(&dev->sem); } diff --git a/drivers/base/core.c b/drivers/base/core.c --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -212,6 +212,7 @@ void device_initialize(struct device *de INIT_LIST_HEAD(&dev->driver_list); INIT_LIST_HEAD(&dev->bus_list); INIT_LIST_HEAD(&dev->dma_pools); + init_MUTEX(&dev->sem); } /** diff --git a/drivers/base/power/resume.c b/drivers/base/power/resume.c --- a/drivers/base/power/resume.c +++ b/drivers/base/power/resume.c @@ -22,6 +22,9 @@ extern int sysdev_resume(void); int resume_device(struct device * dev) { + int error = 0; + + down(&dev->sem); if (dev->power.pm_parent && dev->power.pm_parent->power.power_state) { dev_err(dev, "PM: resume from %d, parent %s still %d\n", @@ -31,9 +34,10 @@ int resume_device(struct device * dev) } if (dev->bus && dev->bus->resume) { dev_dbg(dev,"resuming\n"); - return dev->bus->resume(dev); + error = dev->bus->resume(dev); } - return 0; + up(&dev->sem); + return error; } diff --git a/drivers/base/power/suspend.c b/drivers/base/power/suspend.c --- a/drivers/base/power/suspend.c +++ b/drivers/base/power/suspend.c @@ -39,6 +39,7 @@ int suspend_device(struct device * dev, { int error = 0; + down(&dev->sem); if (dev->power.power_state) { dev_dbg(dev, "PM: suspend %d-->%d\n", dev->power.power_state, state); @@ -58,7 +59,7 @@ int suspend_device(struct device * dev, dev_dbg(dev, "suspending\n"); error = dev->bus->suspend(dev, state); } - + up(&dev->sem); return error; } diff --git a/include/linux/device.h b/include/linux/device.h --- a/include/linux/device.h +++ b/include/linux/device.h @@ -264,6 +264,10 @@ struct device { 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 */ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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