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

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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>
This commit is contained in:
mochel@digitalimplant.org
2005-03-21 10:41:04 -08:00
committed by Greg Kroah-Hartman
parent eb51b65005
commit af70316af1
5 changed files with 24 additions and 6 deletions
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8
drivers/base/power/resume.c
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@@ -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;
}