linux.git/fs/sysfs/file.c, branch v2.6.24

sysfs: fix off-by-one error in fill_read_buffer()

2007-11-28T21:53:53+00:00

I found that there is a off-by-one problem in the following code.

Version:	2.6.24-rc2
File:		fs/sysfs/file.c:118-122
Function:	fill_read_buffer
--------------------------------------------------------------------
	count = ops->show(kobj, attr_sd->s_attr.attr, buffer->page);

	sysfs_put_active_two(attr_sd);

	BUG_ON(count > (ssize_t)PAGE_SIZE);
--------------------------------------------------------------------

Because according to the specification of the sysfs and the implement of
the show methods, the show methods return the number of bytes which would
be generated for the given input, excluding the trailing null.So if the
return value of the show methods equals PAGE_SIZE - 1, the buffer is full
in fact.  And if the return value equals PAGE_SIZE, the resulting string
was already truncated,or buffer overflow occurred.

This patch fixes an off-by-one error in fill_read_buffer.

Signed-off-by: Miao Xie 
Signed-off-by: Andrew Morton 
Acked-by: Tejun Heo 
Signed-off-by: Greg Kroah-Hartman

sysfs: trivial: fix sysfs_create_file kerneldoc spelling mistake

2007-10-20T01:14:32+00:00

Spelling error in sysfs_create_file kerneldoc.

Signed-off-by: Chris Malley 
Signed-off-by: Adrian Bunk

sysfs: add copyrights

2007-10-12T21:51:12+00:00

Sysfs has gone through considerable amount of reimplementation.  Add
copyrights.  Any objections?  :-)

Signed-off-by: Tejun Heo 
Signed-off-by: Greg Kroah-Hartman

sysfs: move sysfs file poll implementation to sysfs_open_dirent

2007-10-12T21:51:11+00:00

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 
Acked-by: Cornelia Huck 
Signed-off-by: Greg Kroah-Hartman

sysfs: implement sysfs_open_dirent

2007-10-12T21:51:11+00:00

Implement sysfs_open_dirent which represents an open file (attribute)
sysfs_dirent.  A file sysfs_dirent with one or more open files have
one sysfs_dirent and all sysfs_buffers (one for each open instance)
are linked to it.

sysfs_open_dirent doesn't actually do anything yet but will be used to
off-load things which are specific for open file sysfs_dirent from it.

Signed-off-by: Tejun Heo 
Acked-by: Cornelia Huck 
Signed-off-by: Greg Kroah-Hartman

sysfs: make s_elem an anonymous union

2007-10-12T21:51:10+00:00

Make s_elem an anonymous union.  Prefixing with s_elem makes things
needlessly longer without any advantage.

Signed-off-by: Tejun Heo 
Acked-by: Cornelia Huck 
Signed-off-by: Greg Kroah-Hartman

sysfs: kill unnecessary NULL pointer check in sysfs_release()

2007-10-12T21:51:10+00:00

In sysfs_release(), sysfs_buffer pointed to by filp->private_data is
guaranteed to exist.  Kill the unnecessary NULL check.  This also
makes the code more consistent with the counterpart in fs/sysfs/bin.c.

Signed-off-by: Tejun Heo 
Acked-by: Cornelia Huck 
Signed-off-by: Greg Kroah-Hartman

sysfs: kill unnecessary sysfs_get() in open paths

2007-10-12T21:51:10+00:00

There's no reason to get an extra reference to sysfs_dirent for an
open file.  Open file has a reference to the dentry which in turn has
a reference to sysfs_dirent.  This is fairly obvious as otherwise open
itself won't be able to access the sysfs_dirent.  Kill the extra
sysfs_get() and matching sysfs_put().

Signed-off-by: Tejun Heo 
Acked-by: Cornelia Huck 
Signed-off-by: Greg Kroah-Hartman

sysfs: kill sysfs_update_file()

2007-10-12T21:51:09+00:00

sysfs_update_file() depends on inode->i_mtime but sysfs iondes are now
reclaimable making the reported modification time unreliable.  There's
only one user (pci hotplug) of this notification mechanism and it
reportedly isn't utilized from userland.

Kill sysfs_update_file().

Signed-off-by: Tejun Heo 
Acked-by: Cornelia Huck 
Signed-off-by: Greg Kroah-Hartman

sysfs: fix sysfs_chmod_file() such that it updates sd->s_mode too

2007-10-12T21:51:09+00:00

sysfs_chmod_file() looked and updated only inode of the target file.
Dentry and inode are reclaimable and the update mode data will go away
when the inode is reclaimed.  This patch makes sysfs_chmod_file()
update sd->s_mode too such that the change is permanent.

Signed-off-by: Tejun Heo 
Acked-by: Cornelia Huck 
Signed-off-by: Greg Kroah-Hartman