On Monday January 14, [EMAIL PROTECTED] wrote:
>
> Thanks. I'll see what I can some up with.
How about this, against current -mm
On both the read and write path for an rdev attribute, we
call mddev_lock, first checking that mddev is not NULL.
Once we get the lock, we check again.
If rdev->mddev is not NULL, we know it will stay that way as it only
gets cleared under the same lock.
While in the rdev show/store routines, we know that the mddev cannot
get freed, do to the kobject relationships.
rdev_size_store is awkward because it has to drop the lock. So we
take a copy of rdev->mddev before the drop, and we are safe...
Comments?
NeilBrown
Signed-off-by: Neil Brown <[EMAIL PROTECTED]>
### Diffstat output
./drivers/md/md.c | 35 ++++++++++++++++++++++++++---------
1 file changed, 26 insertions(+), 9 deletions(-)
diff .prev/drivers/md/md.c ./drivers/md/md.c
--- .prev/drivers/md/md.c 2008-01-14 12:26:15.000000000 +1100
+++ ./drivers/md/md.c 2008-01-14 17:05:53.000000000 +1100
@@ -1998,9 +1998,11 @@ rdev_size_store(mdk_rdev_t *rdev, const
char *e;
unsigned long long size = simple_strtoull(buf, &e, 10);
unsigned long long oldsize = rdev->size;
+ mddev_t *my_mddev = rdev->mddev;
+
if (e==buf || (*e && *e != '\n'))
return -EINVAL;
- if (rdev->mddev->pers)
+ if (my_mddev->pers)
return -EBUSY;
rdev->size = size;
if (size > oldsize && rdev->mddev->external) {
@@ -2013,7 +2015,7 @@ rdev_size_store(mdk_rdev_t *rdev, const
int overlap = 0;
struct list_head *tmp, *tmp2;
- mddev_unlock(rdev->mddev);
+ mddev_unlock(my_mddev);
for_each_mddev(mddev, tmp) {
mdk_rdev_t *rdev2;
@@ -2033,7 +2035,7 @@ rdev_size_store(mdk_rdev_t *rdev, const
break;
}
}
- mddev_lock(rdev->mddev);
+ mddev_lock(my_mddev);
if (overlap) {
/* Someone else could have slipped in a size
* change here, but doing so is just silly.
@@ -2045,8 +2047,8 @@ rdev_size_store(mdk_rdev_t *rdev, const
return -EBUSY;
}
}
- if (size < rdev->mddev->size || rdev->mddev->size == 0)
- rdev->mddev->size = size;
+ if (size < my_mddev->size || my_mddev->size == 0)
+ my_mddev->size = size;
return len;
}
@@ -2067,10 +2069,21 @@ rdev_attr_show(struct kobject *kobj, str
{
struct rdev_sysfs_entry *entry = container_of(attr, struct
rdev_sysfs_entry, attr);
mdk_rdev_t *rdev = container_of(kobj, mdk_rdev_t, kobj);
+ mddev_t *mddev = rdev->mddev;
+ ssize_t rv;
if (!entry->show)
return -EIO;
- return entry->show(rdev, page);
+
+ rv = mddev ? mddev_lock(mddev) : -EBUSY;
+ if (!rv) {
+ if (rdev->mddev == NULL)
+ rv = -EBUSY;
+ else
+ rv = entry->show(rdev, page);
+ mddev_unlock(mddev);
+ }
+ return rv;
}
static ssize_t
@@ -2079,15 +2092,19 @@ rdev_attr_store(struct kobject *kobj, st
{
struct rdev_sysfs_entry *entry = container_of(attr, struct
rdev_sysfs_entry, attr);
mdk_rdev_t *rdev = container_of(kobj, mdk_rdev_t, kobj);
- int rv;
+ ssize_t rv;
+ mddev_t *mddev = rdev->mddev;
if (!entry->store)
return -EIO;
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
- rv = mddev_lock(rdev->mddev);
+ rv = mddev ? mddev_lock(mddev): -EBUSY;
if (!rv) {
- rv = entry->store(rdev, page, length);
+ if (rdev->mddev == NULL)
+ rv = -EBUSY;
+ else
+ rv = entry->store(rdev, page, length);
mddev_unlock(rdev->mddev);
}
return rv;
--
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