Chris Rankin wrote:
> --- Tejun Heo <[EMAIL PROTECTED]> wrote:
>> So, we can fix the problem Chris is seeing by breaking module unload (by
>> allowing it to unload too early). It doesn't sound too hot but module
>> unloading race is much less likely than sysfs node deletion/open race.
>
> Yikes! Just temporary breakage, I hope :-)!! The only modules I unload on a
> regular basis these
> days are things like "microcode", which the init scripts take care of as part
> of the boot-up
> process.
Okay, here's a half-assed fix. With this patch applied, if you try to
unload a module while you're opening it's dev attribute, kernel will
oops later when the file is accessed or closed later but it should fix
the bug winecfg triggers. I really dunno how to fix this the right way
in the stable kernel. Better ideas? Anyone?
--
tejun
---
drivers/base/core.c | 33 ++++++++-------------------------
include/linux/device.h | 1 -
2 files changed, 8 insertions(+), 26 deletions(-)
Index: tree0/drivers/base/core.c
===================================================================
--- tree0.orig/drivers/base/core.c
+++ tree0/drivers/base/core.c
@@ -287,6 +287,8 @@ static ssize_t show_dev(struct device *d
return print_dev_t(buf, dev->devt);
}
+static struct device_attribute devt_attr = __ATTR(dev, S_IRUGO, show_dev, NULL );
+
/*
* devices_subsys - structure to be registered with kobject core.
*/
@@ -490,24 +492,9 @@ int device_add(struct device *dev)
goto attrError;
if (MAJOR(dev->devt)) {
- struct device_attribute *attr;
- attr = kzalloc(sizeof(*attr), GFP_KERNEL);
- if (!attr) {
- error = -ENOMEM;
- goto ueventattrError;
- }
- attr->attr.name = "dev";
- attr->attr.mode = S_IRUGO;
- if (dev->driver)
- attr->attr.owner = dev->driver->owner;
- attr->show = show_dev;
- error = device_create_file(dev, attr);
- if (error) {
- kfree(attr);
+ error = device_create_file(dev, &devt_attr);
+ if (error)
goto ueventattrError;
- }
-
- dev->devt_attr = attr;
}
if (dev->class) {
@@ -568,10 +555,8 @@ int device_add(struct device *dev)
GroupError:
device_remove_attrs(dev);
AttrsError:
- if (dev->devt_attr) {
- device_remove_file(dev, dev->devt_attr);
- kfree(dev->devt_attr);
- }
+ if (MAJOR(dev->devt))
+ device_remove_file(dev, &devt_attr);
ueventattrError:
device_remove_file(dev, &dev->uevent_attr);
attrError:
@@ -650,10 +635,8 @@ void device_del(struct device * dev)
if (parent)
klist_del(&dev->knode_parent);
- if (dev->devt_attr) {
- device_remove_file(dev, dev->devt_attr);
- kfree(dev->devt_attr);
- }
+ if (MAJOR(dev->devt))
+ device_remove_file(dev, &devt_attr);
if (dev->class) {
sysfs_remove_link(&dev->kobj, "subsystem");
/* If this is not a "fake" compatible device, remove the
Index: tree0/include/linux/device.h
===================================================================
--- tree0.orig/include/linux/device.h
+++ tree0/include/linux/device.h
@@ -357,7 +357,6 @@ struct device {
char bus_id[BUS_ID_SIZE]; /* position on parent bus */
unsigned is_registered:1;
struct device_attribute uevent_attr;
- struct device_attribute *devt_attr;
struct semaphore sem; /* semaphore to synchronize calls to
* its driver.
