From foo@baz Tue Apr 9 12:12:43 2002
To: Greg KH <gregkh@suse.de>
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 <mochel@digitalimplant.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
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(-)
--- gregkh-2.6.orig/drivers/base/bus.c 2005-05-12 16:48:53.000000000 -0700
+++ gregkh-2.6/drivers/base/bus.c 2005-05-12 16:49:43.000000000 -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");
@@ -394,6 +401,7 @@
drv->remove(dev);
dev->driver = NULL;
}
+ up(&dev->sem);
}
--- gregkh-2.6.orig/drivers/base/core.c 2005-05-12 16:48:53.000000000 -0700
+++ gregkh-2.6/drivers/base/core.c 2005-05-12 16:49:43.000000000 -0700
@@ -212,6 +212,7 @@
INIT_LIST_HEAD(&dev->driver_list);
INIT_LIST_HEAD(&dev->bus_list);
INIT_LIST_HEAD(&dev->dma_pools);
+ init_MUTEX(&dev->sem);
}
/**
--- gregkh-2.6.orig/drivers/base/power/resume.c 2005-05-12 16:38:56.000000000 -0700
+++ gregkh-2.6/drivers/base/power/resume.c 2005-05-12 16:49:43.000000000 -0700
@@ -22,6 +22,9 @@
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 @@
}
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;
}
--- gregkh-2.6.orig/drivers/base/power/suspend.c 2005-05-12 16:38:56.000000000 -0700
+++ gregkh-2.6/drivers/base/power/suspend.c 2005-05-12 16:49:43.000000000 -0700
@@ -39,6 +39,7 @@
{
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 @@
dev_dbg(dev, "suspending\n");
error = dev->bus->suspend(dev, state);
}
-
+ up(&dev->sem);
return error;
}
--- gregkh-2.6.orig/include/linux/device.h 2005-05-12 16:49:17.000000000 -0700
+++ gregkh-2.6/include/linux/device.h 2005-05-12 16:49:43.000000000 -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 */