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sysfs: move sysfs file poll implementation to sysfs_open_dirent

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Sysfs file poll implementation is scattered over sysfs and kobject.
Event numbering is done in sysfs_dirent but wait itself is done on
kobject.  This not only unecessarily bloats both kobject and
sysfs_dirent but is also buggy - if a sysfs_dirent is removed while
there still are pollers, the associaton betwen the kobject and
sysfs_dirent breaks and kobject may be freed with the pollers still
sleeping on it.

This patch moves whole poll implementation into sysfs_open_dirent.
Each time a sysfs_open_dirent is created, event number restarts from 1
and pollers sleep on sysfs_open_dirent.  As event sequence number is
meaningless without any open file and pollers should have open file
and thus sysfs_open_dirent, this ephemeral event counting works and is
a saner implementation.

This patch fixes the dnagling sleepers bug and reduces the sizes of
kobject and sysfs_dirent by one pointer.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Tejun Heo
2007-09-20 16:05:12 +09:00
committed by Greg Kroah-Hartman
parent 85a4ffad3d
commit a4e8b91254
5 changed files with 19 additions and 10 deletions
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include/linux/kobject.h
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@@ -66,7 +66,6 @@ struct kobject {
struct kset * kset;
struct kobj_type * ktype;
struct sysfs_dirent * sd;
wait_queue_head_t poll;
};
extern int kobject_set_name(struct kobject *, const char *, ...)