kernel_samsung_smdk4412/fs/sysfs/file.c, branch replicant-6.0

sysfs: remove "last sysfs file:" line from the oops messages

2011-05-13T23:05:51+00:00

On some arches (x86, sh, arm, unicore, powerpc) the oops message would
print out the last sysfs file accessed.

This was very useful in finding a number of sysfs and driver core bugs
in the 2.5 and early 2.6 development days, but it has been a number of
years since this file has actually helped in debugging anything that
couldn't also be trivially determined from the stack traceback.

So it's time to delete the line.  This is good as we need all the space
we can get for oops messages at times on consoles.

Acked-by: Phil Carmody 
Acked-by: Ingo Molnar 
Cc: Andrew Morton 
Cc: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

sysfs: checking for NULL instead of ERR_PTR

2010-09-04T00:26:28+00:00

d_path() returns an ERR_PTR and it doesn't return NULL.

Signed-off-by: Dan Carpenter 
Cc: stable 
Reviewed-by: "Eric W. Biederman" 
Signed-off-by: Greg Kroah-Hartman

sysfs: sysfs_chmod_file's attr can be const

2010-08-05T20:53:34+00:00

sysfs_chmod_file doesn't change the attribute it operates on, so this
attribute can be marked const.

Signed-off-by: Jean Delvare 
Signed-off-by: Greg Kroah-Hartman

sysfs: Implement sysfs tagged directory support.

2010-05-21T16:37:31+00:00

The problem.  When implementing a network namespace I need to be able
to have multiple network devices with the same name.  Currently this
is a problem for /sys/class/net/*, /sys/devices/virtual/net/*, and
potentially a few other directories of the form /sys/ ... /net/*.

What this patch does is to add an additional tag field to the
sysfs dirent structure.  For directories that should show different
contents depending on the context such as /sys/class/net/, and
/sys/devices/virtual/net/ this tag field is used to specify the
context in which those directories should be visible.  Effectively
this is the same as creating multiple distinct directories with
the same name but internally to sysfs the result is nicer.

I am calling the concept of a single directory that looks like multiple
directories all at the same path in the filesystem tagged directories.

For the networking namespace the set of directories whose contents I need
to filter with tags can depend on the presence or absence of hotplug
hardware or which modules are currently loaded.  Which means I need
a simple race free way to setup those directories as tagged.

To achieve a reace free design all tagged directories are created
and managed by sysfs itself.

Users of this interface:
- define a type in the sysfs_tag_type enumeration.
- call sysfs_register_ns_types with the type and it's operations
- sysfs_exit_ns when an individual tag is no longer valid

- Implement mount_ns() which returns the ns of the calling process
  so we can attach it to a sysfs superblock.
- Implement ktype.namespace() which returns the ns of a syfs kobject.

Everything else is left up to sysfs and the driver layer.

For the network namespace mount_ns and namespace() are essentially
one line functions, and look to remain that.

Tags are currently represented a const void * pointers as that is
both generic, prevides enough information for equality comparisons,
and is trivial to create for current users, as it is just the
existing namespace pointer.

The work needed in sysfs is more extensive.  At each directory
or symlink creating I need to check if the directory it is being
created in is a tagged directory and if so generate the appropriate
tag to place on the sysfs_dirent.  Likewise at each symlink or
directory removal I need to check if the sysfs directory it is
being removed from is a tagged directory and if so figure out
which tag goes along with the name I am deleting.

Currently only directories which hold kobjects, and
symlinks are supported.  There is not enough information
in the current file attribute interfaces to give us anything
to discriminate on which makes it useless, and there are
no potential users which makes it an uninteresting problem
to solve.

Signed-off-by: Eric W. Biederman 
Signed-off-by: Benjamin Thery 
Signed-off-by: Greg Kroah-Hartman

sysfs: Only take active references on attributes.

2010-03-08T01:04:51+00:00

If we exclude directories and symlinks from the set of sysfs
dirents where we need active references we are left with
sysfs attributes (binary or not).

- Tweak sysfs_deactivate to only do something on attributes
- Move lockdep initialization into sysfs_file_add_mode to
  limit it to just attributes.

Signed-off-by: Eric W. Biederman 
Acked-by: WANG Cong 
Cc: Tejun Heo 
Signed-off-by: Greg Kroah-Hartman

sysfs: Remove sysfs_get/put_active_two

2010-03-08T01:04:51+00:00

It turns out that holding an active reference on a directory is
pointless.  The purpose of the active references are to allows us to
block when removing sysfs entries that have custom methods so we don't
remove modules while running modular code and to keep those custom
methods from accessing data structures after the files have been
removed.  Further sysfs_remove_dir remove all elements in the
directory before removing the directory itself, so there is no chance
we will remove a directory with active children.

Signed-off-by: Eric W. Biederman 
Cc: Tejun Heo 
Signed-off-by: Greg Kroah-Hartman

Driver core: Constify struct sysfs_ops in struct kobj_type

2010-03-08T01:04:49+00:00

Constify struct sysfs_ops.

This is part of the ops structure constification
effort started by Arjan van de Ven et al.

Benefits of this constification:

 * prevents modification of data that is shared
   (referenced) by many other structure instances
   at runtime

 * detects/prevents accidental (but not intentional)
   modification attempts on archs that enforce
   read-only kernel data at runtime

 * potentially better optimized code as the compiler
   can assume that the const data cannot be changed

 * the compiler/linker move const data into .rodata
   and therefore exclude them from false sharing

Signed-off-by: Emese Revfy 
Acked-by: David Teigland 
Acked-by: Matt Domsch 
Acked-by: Maciej Sosnowski 
Acked-by: Hans J. Koch 
Acked-by: Pekka Enberg 
Acked-by: Jens Axboe 
Acked-by: Stephen Hemminger 
Signed-off-by: Greg Kroah-Hartman

sysfs: Add sysfs_add/remove_files utility functions

2010-03-08T01:04:47+00:00

Adding/Removing a whole array of attributes is very common. Add a standard
utility function to do this with a simple function call, instead of
requiring drivers to open code this.

Signed-off-by: Andi Kleen 
Signed-off-by: Greg Kroah-Hartman

sysfs: In sysfs_chmod_file lazily propagate the mode change.

2009-12-11T19:24:54+00:00

Now that sysfs_getattr and sysfs_permission refresh the vfs
inode there is no need to immediatly push the mode change
into the vfs cache.  Reducing the amount of work needed and
simplifying the locking.

Acked-by: Tejun Heo 
Acked-by: Serge Hallyn 
Signed-off-by: Eric W. Biederman 
Signed-off-by: Greg Kroah-Hartman

sysfs: Simplify sysfs_chmod_file semantics

2009-12-11T19:24:53+00:00

Currently every caller of sysfs_chmod_file happens at either
file creation time to set a non-default mode or in response
to a specific user requested space change in policy.  Making
timestamps of when the chmod happens and notification of
a file changing mode uninteresting.

Remove the unnecessary time stamp and filesystem change
notification, and removes the last of the explicit inotify
and donitfy support from sysfs.

Acked-by: Tejun Heo 
Acked-by: Serge Hallyn 
Signed-off-by: Eric W. Biederman 
Signed-off-by: Greg Kroah-Hartman