Acknowledge that the logical sysfs rwsem has one instance per
sysfs attribute with different locking depencencies for different
attributes.

There is a sysfs idiom where writing to one sysfs file causes the
addition or removal of other sysfs files.   Lumping all of the
sysfs attributes together in one lock class causes lockdep to
generate lots of false positives.

This introduces the requirement that non-static sysfs attributes
need to be initialized with sysfs_attr_init or sysfs_bin_attr_init.
Strictly speaking this requirement only exists when lockdep is
enabled, and when lockdep is enabled we get a bit fat warning
if this requirement is not met.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Acked-by: NWANG Cong <xiyou.wangcong@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

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: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Many struct bin_attribute descriptors are purely read-only
structures, and there's no need to change them. Therefore
make the promise not to, which will let those descriptors
be put in a ro section.
Signed-off-by: NPhil Carmody <ext-phil.2.carmody@nokia.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Tejun's commit 7b595756 made sysfs
attribute->owner unnecessary.  But the field was left in the structure to
ease the merge.  It's been over a year since that change and it is now
time to start killing attribute->owner along with its users - one arch at
a time!

This patch is attempt #1 to get rid of attribute->owner only for
CONFIG_X86_64 or CONFIG_X86_32 .  We will deal with other arches later on
as and when possible - avr32 will be the next since that is something I
can test.  Compile (make allyesconfig / make allmodconfig / custom config)
and boot tested.

akpm: the idea is that we put the declaration of sttribute.owner inside
`#ifndef CONFIG_X86'.  But that proved to be too ambitious for now because
new usages kept on turning up in subsystem trees.

[akpm: remove the ifdef for now]
Signed-off-by: NParag Warudkar <parag.lkml@gmail.com>
Cc: Greg KH <greg@kroah.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Tejun Heo <htejun@gmail.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: Roland Dreier <rolandd@cisco.com>
Cc: David Brownell <david-b@pacbell.net>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It finally dawned on me what the clean fix to sysfs_rename_dir
calling kobject_set_name is.  Move the work into kobject_rename
where it belongs.  The callers serialize us anyway so this is
safe.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

When looking at kobject_rename I found two bugs with
that exist when sysfs support is disabled in the kernel.

kobject_rename does not change the name on the kobject when
sysfs support is not compiled in.

kobject_rename without locking attempts to check the
validity of a rename operation, which the kobject layer
simply does not have the infrastructure to do.

This patch documents the previously unstated requirement of
kobject_rename that is the responsibility of the caller to
provide mutual exclusion and to be certain that the new_name
for the kobject is valid.

This patch modifies sysfs_rename_dir in !CONFIG_SYSFS case
to call kobject_set_name to actually change the kobject_name.

This patch removes the bogus and misleading check in kobject_rename
that attempts to see if a rename is valid.  The check is bogus
because we do not have the proper locking.  The check is misleading
because it looks like we can and do perform checking at the kobject
level that we don't.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Because they can be, and because code like this produces a warning if
they're not:

struct device_attribute dev_attr;

sysfs_notify(&kobj, NULL, dev_attr.attr.name);
Signed-off-by: NTrent Piepho <tpiepho@freescale.com>
CC: Neil Brown <neilb@suse.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Support sysfs_notify from atomic context with new sysfs_notify_dirent

sysfs_notify currently takes sysfs_mutex.
This means that it cannot be called in atomic context.
sysfs_mutex  is sometimes held over a malloc (sysfs_rename_dir)
so it can block on low memory.

In md I want to be able to notify on a sysfs attribute from
atomic context, and I don't want to block on low memory because I
could be in the writeout path for freeing memory.

So:
 - export the "sysfs_dirent" structure along with sysfs_get, sysfs_put
   and sysfs_get_dirent so I can get the sysfs_dirent that I want to
   notify on and hold it in an md structure.
 - split sysfs_notify_dirent out of sysfs_notify so the sysfs_dirent
   can be notified on with no blocking (just a spinlock).
Signed-off-by: NNeil Brown <neilb@suse.de>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Print the name of the last-accessed sysfs file when we oops, to help track
down oopses which occur in sysfs store/read handlers.  Because these oopses
tend to not leave any trace of the offending code in the stack traces.

Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

driver core: Suppress sysfs warnings for device_rename().

Renaming network devices to an already existing name is not
something we want sysfs to print a scary warning for, since the
callers can deal with this correctly. So let's introduce
sysfs_create_link_nowarn() which gets rid of the common warning.
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

x86.git testing found the following build failure on v2.6.26-rc1:

  In file included from include/linux/kobject.h:22,
                   from include/linux/module.h:17,
                   from include/linux/crypto.h:22,
                   from arch/x86/kernel/asm-offsets_32.c:8,
                   from arch/x86/kernel/asm-offsets.c:3:
  include/linux/sysfs.h:201: error: redefinition of 'sysfs_update_group'
  include/linux/sysfs.h:195: error: previous definition of 'sysfs_update_group' was here
  make[1]: *** [arch/x86/kernel/asm-offsets.s] Error 1
  make: *** [prepare0] Error 2

with the following config:

    http://redhat.com/~mingo/misc/config-Sun_May__4_07_09_30_CEST_2008.bad

the reason for the build failure is the duplicate definition of the
sysfs_update_group() inline function in include/linux/sysfs.h.

The duplication was a merge error: it was added via -mm by commit
v2.6.25-7262-g2850699c, "sysfs: sysfs_update_group stub for
CONFIG_SYSFS=n" a day before v2.6.26-rc1, but a day before that the same
commit was already merged upstream via the sysfs tree, with commit
v2.6.25-7211-g1cbfb7a5.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

scsi_transport_spi uses sysfs_update_group() when CONFIG_SYSFS=n, so provide a
stub for it.

next-20080423/drivers/scsi/scsi_transport_spi.c:1467: error: implicit declaration of function 'sysfs_update_group'
make[3]: *** [drivers/scsi/scsi_transport_spi.o] Error 1
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Cc: Greg KH <greg@kroah.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

scsi_transport_spi uses sysfs_update_group() when CONFIG_SYSFS=n,
so provide a stub for it.

next-20080423/drivers/scsi/scsi_transport_spi.c:1467: error: implicit declaration of function 'sysfs_update_group'
make[3]: *** [drivers/scsi/scsi_transport_spi.o] Error 1
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

We have a problem in scsi_transport_spi in that we need to customise
not only the visibility of the attributes, but also their mode.  Fix
this by making the is_visible() callback return a mode, with 0
indicating is not visible.

Also add a sysfs_update_group() API to allow us to change either the
visibility or mode of the files at any time on the fly.
Acked-by: NKay Sievers <kay.sievers@vrfy.org>
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>

Convert sysfs_remove_bin_file() to have a return type of 'void' for
!CONFIG_SYSFS configurations.  Also removes unnecessary colons from empty
void functions.
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Reviewed-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This patch allows the various users of attribute_groups to selectively
allow the appearance of group attributes.  The primary consumer of
this will be the transport classes in which we currently have
elaborate attribute selection algorithms to do this same thing.
Acked-by: NGreg KH <greg@kroah.com>
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>

Sysfs has gone through considerable amount of reimplementation.  Add
copyrights.  Any objections?  :-)
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

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: NTejun Heo <htejun@gmail.com>
Acked-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

sysfs is about to go through major overhaul making this a pretty good
opportunity to clean up (out-of-tree changes and pending patches will
need regeneration anyway).  Clean up headers.

* Kill space between * and symbolname.

* Move SYSFS_* type constants and flags into fs/sysfs/sysfs.h.
  They're internal to sysfs.

* Reformat function prototypes and add argument symbol names.

* Make dummy function definition order match that of function
  prototypes.

* Add some comments.

* Reorganize fs/sysfs/sysfs.h according to which file the declared
  variable or feature lives in.

This patch does not introduce any behavior change.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Acked-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

While shadow directories appear to be a good idea, the current scheme
of controlling their creation and destruction outside of sysfs appears
to be a locking and maintenance nightmare in the face of sysfs
directories dynamically coming and going.  Which can now occur for
directories containing network devices when CONFIG_SYSFS_DEPRECATED is
not set.

This patch removes everything from the initial shadow directory support
that allowed the shadow directory creation to be controlled at a higher
level.  So except for a few bits of sysfs_rename_dir everything from
commit b592fcfe is now gone.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Well, first of all, I don't want to change so many files either.

What I do:
Adding a new parameter "struct bin_attribute *" in the
.read/.write methods for the sysfs binary attributes.

In fact, only the four lines change in fs/sysfs/bin.c and
include/linux/sysfs.h do the real work.
But I have to update all the files that use binary attributes
to make them compatible with the new .read and .write methods.
I'm not sure if I missed any. :(

Why I do this:
For a sysfs attribute, we can get a pointer pointing to the
struct attribute in the .show/.store method,
while we can't do this for the binary attributes.
I don't know why this is different, but this does make it not
so handy to use the binary attributes as the regular ones.
So I think this patch is reasonable. :)

Who benefits from it:
The patch that exposes ACPI tables in sysfs
requires such an improvement.
All the table binary attributes share the same .read method.
Parameter "struct bin_attribute *" is used to get
the table signature and instance number which are used to
distinguish different ACPI table binary attributes.

Without this parameter, we need to offer different .read methods
for different ACPI table binary attributes.
This is impossible as there are various ACPI tables on different
platforms, and we don't know what they are until they are loaded.
Signed-off-by: NZhang Rui <rui.zhang@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This patch makes dentries and inodes for sysfs directories
reclaimable.

* sysfs_notify() is modified to walk sysfs_dirent tree instead of
  dentry tree.

* sysfs_update_file() and sysfs_chmod_file() use sysfs_get_dentry() to
  grab the victim dentry.

* sysfs_rename_dir() and sysfs_move_dir() grab all dentries using
  sysfs_get_dentry() on startup.

* Dentries for all shadowed directories are pinned in memory to serve
  as lookup start point.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

As kobj sysfs dentries and inodes are gonna be made reclaimable,
dentry can't be used as naming token for sysfs file/directory, replace
kobj->dentry with kobj->sd.  The only external interface change is
shadow directory handling.  All other changes are contained in kobj
and sysfs.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Implement SYSFS_FLAG_REMOVED flag which currently is used only to
improve sanity check in sysfs_deactivate().  The flag will be used to
make directory entries reclamiable.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Rename sysfs_dirent->s_type to s_flags, pack type into lower eight
bits and reserve the rest for flags.  sysfs_type() can used to access
the type.  All existing sd->s_type accesses are converted to use
sysfs_type().  While at it, type test is changed to equality test
instead of bit-and test where appropriate.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

sysfs is now completely out of driver/module lifetime game.  After
deletion, a sysfs node doesn't access anything outside sysfs proper,
so there's no reason to hold onto the attribute owners.  Note that
often the wrong modules were accounted for as owners leading to
accessing removed modules.

This patch kills now unnecessary attribute->owner.  Note that with
this change, userland holding a sysfs node does not prevent the
backing module from being unloaded.

For more info regarding lifetime rule cleanup, please read the
following message.

  http://article.gmane.org/gmane.linux.kernel/510293

(tweaked by Greg to not delete the field just yet, to make it easier to
merge things properly.)
Signed-off-by: NTejun Heo <htejun@gmail.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Add s_name to sysfs_dirent.  This is to further reduce dependency to
the associated dentry.  Name is copied for directories and symlinks
but not for attributes.

Where possible, name dereferences are converted to use sd->s_name.
sysfs_symlink->link_name and sysfs_get_name() are unused now and
removed.

This change allows symlink to be implemented using sysfs_dirent tree
proper, which is the last remaining dentry-dependent sysfs walk.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This patch (as896b) fixes an oversight in the design of
device_schedule_callback().  It is necessary to acquire a reference to the
module owning the callback routine, to prevent the module from being
unloaded before the callback can run.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Cc: Satyam Sharma <satyam.sharma@gmail.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Since d9a9cdfb <linux/sysfs.h> is using
ENOSYS without including <linux/errno.h> if CONFIG_SYSFS is disabled.

Fixed by including <linux/errno.h>.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch (as868) adds a helper routine for device drivers that need
to set up a callback to perform some action in a different process's
context.  This is intended for use by attribute methods that want to
unregister themselves or their parent device.  Attribute method calls
are mutually exclusive with unregistration, so such actions cannot be
taken directly.

Two attribute methods are converted to use the new helper routine: one
for SCSI device deletion and one for System/390 ccwgroup devices.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Oliver Neukum <oneukum@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

B0rkage introduced by dfa87c82.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch (as860) adds two new sysfs routines:
sysfs_add_file_to_group() and sysfs_remove_file_from_group().
A later patch adds code that uses the new routines.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Cc: Maneesh Soni <maneesh@in.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

struct sysfs_dirent is private to the fs/sysfs/ subtree.  It is
not even referenced as an opaque structure outside of that subtree.

The following patch moves the declaration from include/linux/sysfs.h to
fs/sysfs/sysfs.h, making it clearer that nothing else in the kernel
dereferences it.

I have been running this patch for years.  Please integrate and forward
upstream if there are no objections.

From: "Adam J. Richter" <adam@yggdrasil.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

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/*. 

What I want is a separate /sys/class/net directory in sysfs for each
network namespace, and I want to name each of them /sys/class/net.

I looked and the VFS actually allows that.  All that is needed is
for /sys/class/net to implement a follow link method to redirect
lookups to the real directory you want. 

Implementing a follow link method that is sensitive to the current
network namespace turns out to be 3 lines of code so it looks like a
clean approach.  Modifying sysfs so it doesn't get in my was is a bit
trickier. 

I am calling the concept of multiple directories all at the same path
in the filesystem shadow directories.  With the directory entry really
at that location the shadow master. 

The following patch modifies sysfs so it can handle a directory
structure slightly different from the kobject tree so I can implement
the shadow directories for handling /sys/class/net/.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Cc: Maneesh Soni <maneesh@in.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Sysfs.h uses definitions (e.g. struct list_head s_sibling) from list.h
but does not include it.
Signed-off-by: NFrank Haverkamp <haver@vnet.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Provide a function device_move() to move a device to a new parent device. Add
auxilliary functions kobject_move() and sysfs_move_dir().
kobject_move() generates a new uevent of type KOBJ_MOVE, containing the
previous path (DEVPATH_OLD) in addition to the usual values. For this, a new
interface kobject_uevent_env() is created that allows to add further
environmental data to the uevent at the kobject layer.
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Acked-by: NKay Sievers <kay.sievers@vrfy.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Don't be crufty.  Mark it __must_check too.

Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

We're getting a lot of crashes in the sysfs/kobject/device/bus/class code and
they're very hard to diagnose.

I'm suspecting that in some cases this is because drivers aren't checking
return values and aren't handling errors correctly.  So the code blithely
blunders on and crashes later in very obscure ways.

There's just no reason to ignore errors which can and do occur.  So the patch
sprinkles __must_check all over these APIs.

Causes 1,513 new warnings.  Heh.
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Make sysfs_remove_bin_file() void.  If it detects an error,
printk the file name and call dump_stack().

sysfs_hash_and_remove() now returns an error code indicating
its success or failure so that sysfs_remove_bin_file() can
know success/failure.

Convert the only driver that checked the return value of
sysfs_remove_bin_file().
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

It works like this:
  Open the file
  Read all the contents.
  Call poll requesting POLLERR or POLLPRI (so select/exceptfds works)
  When poll returns,
     close the file and go to top of loop.
   or lseek to start of file and go back to the 'read'.

Events are signaled by an object manager calling
   sysfs_notify(kobj, dir, attr);

If the dir is non-NULL, it is used to find a subdirectory which
contains the attribute (presumably created by sysfs_create_group).

This has a cost of one int  per attribute, one wait_queuehead per kobject,
one int per open file.

The name "sysfs_notify" may be confused with the inotify
functionality.  Maybe it would be nice to support inotify for sysfs
attributes as well?

This patch also uses sysfs_notify to allow /sys/block/md*/md/sync_action
to be pollable
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>