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sysfs bin file handling will be merged into the regular file support.
This patch prepares the open path.
This patch updates sysfs_open_file() such that it can handle both
regular and bin files.
This is a preparation and the new bin file path isn't used yet.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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sysfs bin file handling will be merged into the regular file support.
This patch copies mmap support from bin so that fs/sysfs/file.c can
handle mmapping bin files.
The code is copied mostly verbatim with the following updates.
* ->mmapped and ->vm_ops are added to sysfs_open_file and bin_buffer
references are replaced with sysfs_open_file ones.
* Symbols are prefixed with sysfs_.
* sysfs_unmap_bin_file() grabs sysfs_open_dirent and traverses
->files. Invocation of this function is added to
sysfs_addrm_finish().
* sysfs_bin_mmap() is added to sysfs_bin_operations.
This is a preparation and the new mmap path isn't used yet.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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sysfs bin file handling will be merged into the regular file support.
This patch prepares the read path.
Copy fs/sysfs/bin.c::read() to fs/sysfs/file.c and make it use
sysfs_open_file instead of bin_buffer. The function is identical copy
except for the use of sysfs_open_file.
The new function is added to sysfs_bin_operations. This isn't used
yet but will eventually replace fs/sysfs/bin.c.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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sysfs bin file handling will be merged into the regular file support.
This patch prepares the write path.
bin file write is almost identical to regular file write except that
the write length is capped by the inode size and @off is passed to the
write method. This patch adds bin file handling to sysfs_write_file()
so that it can handle both regular and bin files.
A new file_operations struct sysfs_bin_operations is added, which
currently only hosts sysfs_write_file() and generic_file_llseek().
This isn't used yet but will eventually replace fs/sysfs/bin.c.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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sysfs read path implements its own buffering scheme between userland
and kernel callbacks, which essentially is a degenerate duplicate of
seq_file. This patch replaces the custom read buffering
implementation in sysfs with seq_file.
While the amount of code reduction is small, this reduces low level
hairiness and enables future development of a new versatile API based
on seq_file so that sysfs features can be shared with other
subsystems.
As write path was already converted to not use sysfs_open_file->page,
this patch makes ->page and ->count unused and removes them.
Userland behavior remains the same except for some extreme corner
cases - e.g. sysfs will now regenerate the content each time a file is
read after a non-contiguous seek whereas the original code would keep
using the same content. While this is a userland visible behavior
change, it is extremely unlikely to be noticeable and brings sysfs
behavior closer to that of procfs.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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There isn't much to be gained by keeping around kernel buffer while a
file is open especially as the read path planned to be converted to
use seq_file and won't use the buffer. This patch makes
sysfs_write_file() use per-write transient buffer instead of
sysfs_open_file->page.
This simplifies the write path, enables removing sysfs_open_file->page
once read path is updated and will help merging bin file write path
which already requires the use of a transient buffer due to a locking
order issue.
As the function comments of flush_write_buffer() and
sysfs_write_buffer() are being updated anyway, reformat them so that
they're more conventional.
v2: Use min_t() instead of min() in sysfs_write_file() to avoid build
warning on arm. Reported by build test robot.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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sysfs will be converted to use seq_file for read path, which will make
it difficult to pass around multiple pointers directly. This patch
adds sysfs_open_file->sd and ->file so that we can reach all the
necessary data structures from sysfs_open_file.
flush_write_buffer() is updated to drop @dentry which was used to
discover the sysfs_dirent as it's now available through
sysfs_open_file->sd.
This patch doesn't cause any behavior difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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sysfs read path will be converted to use seq_file which will handle
buffering making sysfs_buffer a misnomer. Rename sysfs_buffer to
sysfs_open_file, and sysfs_open_dirent->buffers to ->files.
This path is pure rename.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Add a separate mutex to protect sysfs_open_dirent->buffers list. This
will allow performing sleepable operations while traversing
sysfs_buffers, which will be renamed to sysfs_open_file.
Note that currently sysfs_open_dirent->buffers list isn't being used
for anything and this patch doesn't make any functional difference.
It will be used to merge regular and bin file supports.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Currently, sysfs_ops is fetched during sysfs_open_file() and cached in
sysfs_buffer->ops to be used while the file is open. This patch
removes the caching and makes each operation directly fetch sysfs_ops.
This patch doesn't introduce any behavior difference and is to prepare
for merging regular and bin file supports.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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->needs_read_fill is used to implement the following behaviors.
1. Ensure buffer filling on the first read.
2. Force buffer filling after a write.
3. Force buffer filling after a successful poll.
However, #2 and #3 don't really work as sysfs doesn't reset file
position. While the read buffer would be refilled, the next read
would continue from the position after the last read or write,
requiring an explicit seek to the start for it to be useful, which
makes ->needs_read_fill superflous as read buffer is always refilled
if f_pos == 0.
Update sysfs_read_file() to test buffer->page for #1 instead and
remove ->needs_read_fill. While this changes behavior in extreme
corner cases - e.g. re-reading a sysfs file after seeking to non-zero
position after a write or poll, it's highly unlikely to lead to actual
breakage. This change is to prepare for using seq_file in the read
path.
While at it, reformat a comment in fill_write_buffer().
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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sysfs_addrm_start/finish() enclose sysfs_dirent additions and
deletions and sysfs_addrm_cxt is used to record information necessary
to finish the operations. Currently, sysfs_addrm_start() takes
@parent_sd, records it in sysfs_addrm_cxt, and assumes that all
operations in the block are performed under that @parent_sd.
This assumption has been fine until now but we want to make some
operations behave recursively and, while having @parent_sd recorded in
sysfs_addrm_cxt doesn't necessarily prevents that, it becomes
confusing.
This patch removes sysfs_addrm_cxt->parent_sd and makes
sysfs_add_one() take an explicit @parent_sd parameter. Note that
sysfs_remove_one() doesn't need the extra argument as its parent is
always known from the target @sd.
While at it, add __acquires/releases() notations to
sysfs_addrm_start/finish() respectively.
This patch doesn't make any functional difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Some internal sysfs functions which take explicit namespace argument
are weird in that they place the optional @ns in front of @name which
is contrary to the established convention. This is confusing and
error-prone especially as @ns and @name may be interchanged without
causing compilation warning.
Swap the positions of @name and @ns in the following internal
functions.
sysfs_find_dirent()
sysfs_rename()
sysfs_hash_and_remove()
sysfs_name_hash()
sysfs_name_compare()
create_dir()
This patch doesn't introduce any functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The pre-existing sysfs interfaces which take explicit namespace
argument are weird in that they place the optional @ns in front of
@name which is contrary to the established convention. For example,
we end up forcing vast majority of sysfs_get_dirent() users to do
sysfs_get_dirent(parent, NULL, name), which is silly and error-prone
especially as @ns and @name may be interchanged without causing
compilation warning.
This renames sysfs_get_dirent() to sysfs_get_dirent_ns() and swap the
positions of @name and @ns, and sysfs_get_dirent() is now a wrapper
around sysfs_get_dirent_ns(). This makes confusions a lot less
likely.
There are other interfaces which take @ns before @name. They'll be
updated by following patches.
This patch doesn't introduce any functional changes.
v2: EXPORT_SYMBOL_GPL() wasn't updated leading to undefined symbol
error on module builds. Reported by build test robot. Fixed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kay Sievers <kay@vrfy.org>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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sysfs ns (namespace) implementation became more convoluted than
necessary while trying to hide ns information from visible interface.
The relatively recent attr ns support is a good example.
* attr ns tag is determined by sysfs_ops->namespace() callback while
dir tag is determined by kobj_type->namespace(). The placement is
arbitrary.
* Instead of performing operations with explicit ns tag, the namespace
callback is routed through sysfs_attr_ns(), sysfs_ops->namespace(),
class_attr_namespace(), class_attr->namespace(). It's not simpler
in any sense. The only thing this convolution does is traversing
the whole stack backwards.
The namespace callbacks are unncessary because the operations involved
are inherently synchronous. The information can be provided in in
straight-forward top-down direction and reversing that direction is
unnecessary and against basic design principles.
This backward interface is unnecessarily convoluted and hinders
properly separating out sysfs from driver model / kobject for proper
layering. This patch updates attr ns support such that
* sysfs_ops->namespace() and class_attr->namespace() are dropped.
* sysfs_{create|remove}_file_ns(), which take explicit @ns param, are
added and sysfs_{create|remove}_file() are now simple wrappers
around the ns aware functions.
* ns handling is dropped from sysfs_chmod_file(). Nobody uses it at
this point. sysfs_chmod_file_ns() can be added later if necessary.
* Explicit @ns is propagated through class_{create|remove}_file_ns()
and netdev_class_{create|remove}_file_ns().
* driver/net/bonding which is currently the only user of attr
namespace is updated to use netdev_class_{create|remove}_file_ns()
with @bh->net as the ns tag instead of using the namespace callback.
This patch should be an equivalent conversion without any functional
difference. It makes the code easier to follow, reduces lines of code
a bit and helps proper separation and layering.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kay Sievers <kay@vrfy.org>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This fixes the coding style warnings in fs/sysfs/file.c for broken
strings across lines.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This fixes the uaccess.h warnings in the sysfs.c files.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This fixes up the 80 column coding style issues in the sysfs .c files.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This fixes up all of the space-related coding style issues for the sysfs
code.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This removes all trailing whitespace errors in the sysfs code.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The export should happen after the function, not at the bottom of the
file, so fix that up.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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If sysfs_notify is called on a binary attribute, bad things can
happen, so prevent it.
Note, no in-kernel usage of this is currently present, but in the
future, it's good to be safe.
Changes in V2:
- Also ignore sysfs_notify on dirs, links
- Use WARN_ON rather than silently failing
- Compiled and tested (huge apologies about first submission)
Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Nothing outside of fs/sysfs/file.c references this function, so mark it static.
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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directories.
Recently an OOPS was observed from the usb serial io_ti driver when it tried to remove
sysfs directories. Upon investigation it turns out this driver was always buggy
and that a recent sysfs change had stopped guarding itself against removing attributes
from sysfs directories that had already been removed. :(
Historically we have been silent about attempting to files from nonexistent sysfs
directories and have politely returned error codes. That has resulted in people writing
broken code that ignores the error codes.
Issue a kernel WARNING and a stack backtrace to make it clear in no uncertain
terms that abusing sysfs is not ok, and the callers need to fix their code.
This change transforms the io_ti OOPS into a more comprehensible error message
and stack backtrace.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Reported-by: Wolfgang Frisch <wfpub@roembden.net>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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sysfs is a core piece of ifrastructure that many people use and
few people have all of the rules in their head on how to use
it correctly. Add warnings for people using tagged directories
improperly to that any misuses can be caught and diagnosed quickly.
A single inexpensive test in sysfs_find_dirent is almost sufficient
to catch all possible misuses. An additional warning is needed
in sysfs_add_dirent so that we actually fail when attempting to
add an untagged dirent in a tagged directory.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Looking up files in sysfs is hard to understand and analyize because we
currently allow placing untagged files in tagged directories. In the
implementation of that we have two subtly different meanings of NULL.
NULL meaning there is no tag on a directory entry and NULL meaning
we don't care which namespace the lookup is performed for. This
multiple uses of NULL have resulted in subtle bugs (since fixed)
in the code.
Currently it is only the bonding driver that needs to have an untagged
file in a tagged directory.
To untagle this mess I am adding support for tagged files to sysfs.
Modifying the bonding driver to implement bonding_masters as a tagged
file. Registering bonding_masters once for each network namespace.
Then I am removing support for untagged entries in tagged sysfs
directories.
Resulting in code that is much easier to reason about.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
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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 <ext-phil.2.carmody@nokia.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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d_path() returns an ERR_PTR and it doesn't return NULL.
Signed-off-by: Dan Carpenter <error27@gmail.com>
Cc: stable <stable@kernel.org>
Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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sysfs_chmod_file doesn't change the attribute it operates on, so this
attribute can be marked const.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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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 <ebiederm@xmission.com>
Signed-off-by: Benjamin Thery <benjamin.thery@bull.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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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 <ebiederm@xmission.com>
Acked-by: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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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 <ebiederm@xmission.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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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 <re.emese@gmail.com>
Acked-by: David Teigland <teigland@redhat.com>
Acked-by: Matt Domsch <Matt_Domsch@dell.com>
Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Acked-by: Hans J. Koch <hjk@linutronix.de>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Acked-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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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 <ak@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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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 <tj@kernel.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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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 <tj@kernel.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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sysfs_notify_dirent is a simple atomic operation that can be used to
alert user-space that new data can be read from a sysfs attribute.
Unfortunately it cannot currently be called from non-process context
because of its use of spin_lock which is sometimes taken with
interrupts enabled.
So change all lockers of sysfs_open_dirent_lock to disable interrupts,
thus making sysfs_notify_dirent safe to be called from non-process
context (as drivers/md does in md_safemode_timeout).
sysfs_get_open_dirent is (documented as being) only called from
process context, so it uses spin_lock_irq. Other places
use spin_lock_irqsave.
The usage for sysfs_notify_dirent in md_safemode_timeout was
introduced in 2.6.28, so this patch is suitable for that and more
recent kernels.
Reported-by: Joel Andres Granados <jgranado@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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We don't need a kernel thread per CPU for this application.
Acked-by: Alex Chiang <achiang@hp.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Currently, following test programs don't finished.
% ruby -e '
Thread.new { sleep }
File.read("/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies")
'
strace expose the reason.
...
open("/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies", O_RDONLY|O_LARGEFILE) = 3
ioctl(3, SNDCTL_TMR_TIMEBASE or TCGETS, 0xbf9fa6b8) = -1 ENOTTY (Inappropriate ioctl for device)
fstat64(3, {st_mode=S_IFREG|0444, st_size=4096, ...}) = 0
_llseek(3, 0, [0], SEEK_CUR) = 0
select(4, [3], NULL, NULL, NULL) = 1 (in [3])
read(3, "1400000 1300000 1200000 1100000 1"..., 4096) = 62
select(4, [3], NULL, NULL, NULL
Because Ruby (the scripting language) VM assume select system-call
against regular file don't block. it because SUSv3 says "Regular files
shall always poll TRUE for reading and writing". see
http://www.opengroup.org/onlinepubs/009695399/functions/poll.html it
seems valid assumption.
But sysfs_poll() don't keep this rule although sysfs file can read and
write always.
This patch restore proper poll behavior to sysfs.
/sys/block/md*/md/sync_action polling application and another sysfs
updating sensitive application still can use POLLERR and POLLPRI.
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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A sysfs attribute using sysfs_schedule_callback() to commit suicide
may end up calling device_unregister(), which will eventually call
a driver's ->remove function.
Drivers may call flush_scheduled_work() in their shutdown routines,
in which case lockdep will complain with something like the following:
=============================================
[ INFO: possible recursive locking detected ]
2.6.29-rc8-kk #1
---------------------------------------------
events/4/56 is trying to acquire lock:
(events){--..}, at: [<ffffffff80257fc0>] flush_workqueue+0x0/0xa0
but task is already holding lock:
(events){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230
other info that might help us debug this:
3 locks held by events/4/56:
#0: (events){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230
#1: (&ss->work){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230
#2: (pci_remove_rescan_mutex){--..}, at: [<ffffffff803c10d1>] remove_callback+0x21/0x40
stack backtrace:
Pid: 56, comm: events/4 Not tainted 2.6.29-rc8-kk #1
Call Trace:
[<ffffffff8026dfcd>] validate_chain+0xb7d/0x1260
[<ffffffff8026eade>] __lock_acquire+0x42e/0xa40
[<ffffffff8026f148>] lock_acquire+0x58/0x80
[<ffffffff80257fc0>] ? flush_workqueue+0x0/0xa0
[<ffffffff8025800d>] flush_workqueue+0x4d/0xa0
[<ffffffff80257fc0>] ? flush_workqueue+0x0/0xa0
[<ffffffff80258070>] flush_scheduled_work+0x10/0x20
[<ffffffffa0144065>] e1000_remove+0x55/0xfe [e1000e]
[<ffffffff8033ee30>] ? sysfs_schedule_callback_work+0x0/0x50
[<ffffffff803bfeb2>] pci_device_remove+0x32/0x70
[<ffffffff80441da9>] __device_release_driver+0x59/0x90
[<ffffffff80441edb>] device_release_driver+0x2b/0x40
[<ffffffff804419d6>] bus_remove_device+0xa6/0x120
[<ffffffff8043e46b>] device_del+0x12b/0x190
[<ffffffff8043e4f6>] device_unregister+0x26/0x70
[<ffffffff803ba969>] pci_stop_dev+0x49/0x60
[<ffffffff803baab0>] pci_remove_bus_device+0x40/0xc0
[<ffffffff803c10d9>] remove_callback+0x29/0x40
[<ffffffff8033ee4f>] sysfs_schedule_callback_work+0x1f/0x50
[<ffffffff8025769a>] run_workqueue+0x15a/0x230
[<ffffffff80257648>] ? run_workqueue+0x108/0x230
[<ffffffff8025846f>] worker_thread+0x9f/0x100
[<ffffffff8025bce0>] ? autoremove_wake_function+0x0/0x40
[<ffffffff802583d0>] ? worker_thread+0x0/0x100
[<ffffffff8025b89d>] kthread+0x4d/0x80
[<ffffffff8020d4ba>] child_rip+0xa/0x20
[<ffffffff8020cebc>] ? restore_args+0x0/0x30
[<ffffffff8025b850>] ? kthread+0x0/0x80
[<ffffffff8020d4b0>] ? child_rip+0x0/0x20
Although we know that the device_unregister path will never acquire
a lock that a driver might try to acquire in its ->remove, in general
we should never attempt to flush a workqueue from within the same
workqueue, and lockdep rightly complains.
So as long as sysfs attributes cannot commit suicide directly and we
are stuck with this callback mechanism, put the sysfs callbacks on
their own workqueue instead of the global one.
This has the side benefit that if a suicidal sysfs attribute kicks
off a long chain of ->remove callbacks, we no longer induce a long
delay on the global queue.
This also fixes a missing module_put in the error path introduced
by sysfs-only-allow-one-scheduled-removal-callback-per-kobj.patch.
We never destroy the workqueue, but I'm not sure that's a
problem.
Reported-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Tested-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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The only way for a sysfs attribute to remove itself (without
deadlock) is to use the sysfs_schedule_callback() interface.
Vegard Nossum discovered that a poorly written sysfs ->store
callback can repeatedly schedule remove callbacks on the same
device over and over, e.g.
$ while true ; do echo 1 > /sys/devices/.../remove ; done
If the 'remove' attribute uses the sysfs_schedule_callback API
and also does not protect itself from concurrent accesses, its
callback handler will be called multiple times, and will
eventually attempt to perform operations on a freed kobject,
leading to many problems.
Instead of requiring all callers of sysfs_schedule_callback to
implement their own synchronization, provide the protection in
the infrastructure.
Now, sysfs_schedule_callback will only allow one scheduled
callback per kobject. On subsequent calls with the same kobject,
return -EAGAIN.
This is a short term fix. The long term fix is to allow sysfs
attributes to remove themselves directly, without any of this
callback hokey pokey.
[cornelia.huck@de.ibm.com: s390 ccwgroup bits]
Reported-by: vegard.nossum@gmail.com
Signed-off-by: Alex Chiang <achiang@hp.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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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: Trent Piepho <tpiepho@freescale.com>
CC: Neil Brown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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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: Neil Brown <neilb@suse.de>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Use WARN() instead of a printk+WARN_ON() pair; this way the message becomes
part of the warning section for better reporting/collection. Also, with this,
one fo the if() sections collapses entirely into the WARN().
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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sysfs_chmod_file() calls notify_change() to change the permission bits
on a sysfs file. Replace with explicit call to sysfs_setattr() and
fsnotify_change().
This is equivalent, except that security_inode_setattr() is not
called. This function is called by drivers, so the security checks do
not make any sense.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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__FUNCTION__ is gcc-specific, use __func__
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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