sysfs: Skip empty folders creation

Most sysfs attributes are statically defined, the goal with this design
being to be able to move all the filesystem description into read-only
memory. Anyway, it m

sysfs: Skip empty folders creation

Most sysfs attributes are statically defined, the goal with this design
being to be able to move all the filesystem description into read-only
memory. Anyway, it may be relevant in some cases to populate attributes
at run time. This leads to situation where an attribute may or may not be
present depending on conditions which are not known at compile
time, up to the point where no attribute at all gets added in a folder
which then becomes "sometimes" empty. Problem is, providing an attribute
group with a name and without .[bin_]attrs members will be loudly
refused by the core, leading in most cases to a device registration
failure.

The simple way to support such situation right now is to dynamically
allocate an empty attribute array, which is:
* a (small) waste of space
* a waste of time
* disturbing, to say the least, as an empty sysfs folder will be created
anyway.

Another (even worse) possibility would be to dynamically overwrite a
member of the attribute_group list, hopefully the last, which is also
supposed to remain in the read-only section.

In order to avoid these hackish situations, while still giving a little
bit of flexibility, we might just check the validity of the .[bin_]attrs
list and, if empty, just skip the attribute group creation instead of
failing. This way, developers will not be tempted to workaround the
core with useless allocations or strange writes on supposedly read-only
structures.

The content of the WARN() message is kept but turned into a debug
message in order to help developers understanding why their sysfs
folders might now silently fail to be created.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Message-ID: <20230614063018.2419043-3-miquel.raynal@bootlin.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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sysfs: Improve readability by following the kernel coding style

The purpose of the if/else block is to select the right sysfs directory
entry to be used for the files creation. At a first look when

sysfs: Improve readability by following the kernel coding style

The purpose of the if/else block is to select the right sysfs directory
entry to be used for the files creation. At a first look when you have
the file in front of you, it really seems like the "create_files()"
lines right after the block are badly indented and the "else" does not
guard. In practice the code is correct but lacks curly brackets to show
where the big if/else block actually ends. Add these brackets to comply
with the current kernel coding style and to ease the understanding of
the whole logic.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Message-ID: <20230614063018.2419043-2-miquel.raynal@bootlin.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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sysfs: split out binary attribute handling from sysfs_add_file_mode_ns

Split adding binary attributes into a separate handler instead of
overloading sysfs_add_file_mode_ns.

Acked-by: Christian Brau

sysfs: split out binary attribute handling from sysfs_add_file_mode_ns

Split adding binary attributes into a separate handler instead of
overloading sysfs_add_file_mode_ns.

Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210913054121.616001-5-hch@lst.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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sysfs: Use local reference in compat_only_sysfs_link_entry_to_kobj()

As we have just obtained target_kobj->sd into a local variable, and
incremented the object's reference count, it is better to use

sysfs: Use local reference in compat_only_sysfs_link_entry_to_kobj()

As we have just obtained target_kobj->sd into a local variable, and
incremented the object's reference count, it is better to use the local
variable instead of the original reference.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/20210714151559.2532572-1-geert@linux-m68k.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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sysfs: remove redundant __compat_only_sysfs_link_entry_to_kobj fn

Commit 9255782f7061 ("sysfs: Wrap __compat_only_sysfs_link_entry_to_kobj
function to change the symlink name") made this function a

sysfs: remove redundant __compat_only_sysfs_link_entry_to_kobj fn

Commit 9255782f7061 ("sysfs: Wrap __compat_only_sysfs_link_entry_to_kobj
function to change the symlink name") made this function a wrapper
around a new non-underscored function, which is a bit odd. The normal
naming convention is the other way around: the underscored function is
the wrappee, and the non-underscored function is the wrapper.

There's only one single user (well, two call-sites in that user) of the
more limited double underscore version of this function, so just remove
the oddly named wrapper entirely and just add the extra NULL argument to
the user.

I considered just doing that in the merge, but that tends to make
history really hard to read.

Link: https://lore.kernel.org/lkml/CAHk-=wgkkmNV5tMzQDmPAQuNJBuMcry--Jb+h8H1o4RA3kF7QQ@mail.gmail.com/
Cc: Sourabh Jain <sourabhjain@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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sysfs: add sysfs_group{s}_change_owner()

Add helpers to change the owner of sysfs groups.
This function will be used to correctly account for kobject ownership
changes, e.g. when moving network devi

sysfs: add sysfs_group{s}_change_owner()

Add helpers to change the owner of sysfs groups.
This function will be used to correctly account for kobject ownership
changes, e.g. when moving network devices between network namespaces.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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sysfs: Wrap __compat_only_sysfs_link_entry_to_kobj function to change the symlink name

The __compat_only_sysfs_link_entry_to_kobj function creates a symlink
to a kobject but doesn't provide an optio

sysfs: Wrap __compat_only_sysfs_link_entry_to_kobj function to change the symlink name

The __compat_only_sysfs_link_entry_to_kobj function creates a symlink
to a kobject but doesn't provide an option to change the symlink file
name.

This patch adds a wrapper function compat_only_sysfs_link_entry_to_kobj
that extends the __compat_only_sysfs_link_entry_to_kobj functionality
which allows function caller to customize the symlink name.

Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
[mpe: Fix compile error when CONFIG_SYSFS=n]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191211160910.21656-3-sourabhjain@linux.ibm.com

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treewide: remove redundant IS_ERR() before error code check

'PTR_ERR(p) == -E*' is a stronger condition than IS_ERR(p).
Hence, IS_ERR(p) is unneeded.

The semantic patch that generates this commit i

treewide: remove redundant IS_ERR() before error code check

'PTR_ERR(p) == -E*' is a stronger condition than IS_ERR(p).
Hence, IS_ERR(p) is unneeded.

The semantic patch that generates this commit is as follows:

// <smpl>
@@
expression ptr;
constant error_code;
@@
-IS_ERR(ptr) && (PTR_ERR(ptr) == - error_code)
+PTR_ERR(ptr) == - error_code
// </smpl>

Link: http://lkml.kernel.org/r/20200106045833.1725-1-masahiroy@kernel.org
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Acked-by: Stephen Boyd <sboyd@kernel.org> [drivers/clk/clk.c]
Acked-by: Bartosz Golaszewski <bgolaszewski@baylibre.com> [GPIO]
Acked-by: Wolfram Sang <wsa@the-dreams.de> [drivers/i2c]
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> [acpi/scan.c]
Acked-by: Rob Herring <robh@kernel.org>
Cc: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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sysfs: Add sysfs_update_groups function

Adding sysfs_update_groups function to update
multiple groups.

sysfs_update_groups - given a directory kobject, create a bunch of attribute groups
@kobj:

sysfs: Add sysfs_update_groups function

Adding sysfs_update_groups function to update
multiple groups.

sysfs_update_groups - given a directory kobject, create a bunch of attribute groups
@kobj: The kobject to update the group on
@groups: The attribute groups to update, NULL terminated

This function update a bunch of attribute groups. If an error occurs when
updating a group, all previously updated groups will be removed together
with already existing (not updated) attributes.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190512155518.21468-2-jolsa@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

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sysfs: convert BUG_ON to WARN_ON

It's rude to crash the system just because the developer did something
wrong, as it prevents them from usually even seeing what went wrong.

So convert the few BUG_O

sysfs: convert BUG_ON to WARN_ON

It's rude to crash the system just because the developer did something
wrong, as it prevents them from usually even seeing what went wrong.

So convert the few BUG_ON() calls that have snuck into the sysfs code
over the years to WARN_ON() to make it more "friendly". All of these
are able to be recovered from, so it makes no sense to crash.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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sysfs: Fix internal_create_group() for named group updates

There are a couple of problems with named group updates in the code
today:

* sysfs_update_group() will always fail for a named group, beca

sysfs: Fix internal_create_group() for named group updates

There are a couple of problems with named group updates in the code
today:

* sysfs_update_group() will always fail for a named group, because
internal_create_group() will try to create a new sysfs directory
unconditionally, which will ofcourse fail with -EEXIST.

* We can leak the kernfs_node for grp->name if some one tries to:
- rename a group (change grp->name), or
- update a named group, to an unnamed group

It appears that the whole purpose of sysfs_update_group() was to
allow changing the permissions or visibility of attributes and not
the names. So make it clear in the comments, and allow it to update
an existing named group.

Signed-off-by: Rajat Jain <rajatja@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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sysfs, kobject: allow creating kobject belonging to arbitrary users

Normally kobjects and their sysfs representation belong to global root,
however it is not necessarily the case for objects in sepa

sysfs, kobject: allow creating kobject belonging to arbitrary users

Normally kobjects and their sysfs representation belong to global root,
however it is not necessarily the case for objects in separate namespaces.
For example, objects in separate network namespace logically belong to the
container's root and not global root.

This change lays groundwork for allowing network namespace objects
ownership to be transferred to container's root user by defining
get_ownership() callback in ktype structure and using it in sysfs code to
retrieve desired uid/gid when creating sysfs objects for given kobject.

Co-Developed-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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sysfs: use SPDX identifiers

Move the license "mark" of the sysfs files to be in SPDX form, instead
of the custom text that it currently is in. This is in a quest to get
rid of the 700+ different wa

sysfs: use SPDX identifiers

Move the license "mark" of the sysfs files to be in SPDX form, instead
of the custom text that it currently is in. This is in a quest to get
rid of the 700+ different ways we say "GPLv2" in the kernel tree.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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sysfs: Use PTR_ERR_OR_ZERO()

Fix ptr_ret.cocci warnings:
fs/sysfs/group.c:409:8-14: WARNING: PTR_ERR_OR_ZERO can be used

Use PTR_ERR_OR_ZERO rather than if(IS_ERR(...)) + PTR_ERR

Generated by: scr

sysfs: Use PTR_ERR_OR_ZERO()

Fix ptr_ret.cocci warnings:
fs/sysfs/group.c:409:8-14: WARNING: PTR_ERR_OR_ZERO can be used

Use PTR_ERR_OR_ZERO rather than if(IS_ERR(...)) + PTR_ERR

Generated by: scripts/coccinelle/api/ptr_ret.cocci

Signed-off-by: Vasyl Gomonovych <gomonovych@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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sysfs print name of undiscoverable attribute group

Print the name of an undiscoverable attribute group and not the
pointer's address.

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-o

sysfs print name of undiscoverable attribute group

Print the name of an undiscoverable attribute group and not the
pointer's address.

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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sysfs: added __compat_only_sysfs_link_entry_to_kobj()

Added a new function __compat_only_sysfs_link_group_to_kobj() that adds
a symlink from attribute or group to a kobject. This needed for
maintain

sysfs: added __compat_only_sysfs_link_entry_to_kobj()

Added a new function __compat_only_sysfs_link_group_to_kobj() that adds
a symlink from attribute or group to a kobject. This needed for
maintaining backwards compatibility with PPI attributes in the TPM
driver.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>

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sysfs: Support is_visible() on binary attributes

According to the sysfs header file:

"The returned value will replace static permissions defined in
struct attribute or struct bin_attribute

sysfs: Support is_visible() on binary attributes

According to the sysfs header file:

"The returned value will replace static permissions defined in
struct attribute or struct bin_attribute."

but this isn't the case, as is_visible is only called on struct attribute
only. This patch introduces a new is_bin_visible() function to implement
the same functionality for binary attributes, and updates documentation
accordingly.

Note that to keep functionality and code similar to that of normal
attributes, the mode is now checked as well to ensure it contains only
read/write permissions or SYSFS_PREALLOC.

Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Emilio López <emilio.lopez@collabora.co.uk>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Olof Johansson <olof@lixom.net>

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sysfs: disambiguate between "error code" and "failure" in comments

The sentence "Returns 0 on success or error" might be misinterpreted as
"the function will always returns 0", make it less ambiguou

sysfs: disambiguate between "error code" and "failure" in comments

The sentence "Returns 0 on success or error" might be misinterpreted as
"the function will always returns 0", make it less ambiguous.

Also, use the word "failure" as the contrary of "success".

Signed-off-by: Antonio Ospite <ao2@ao2.it>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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sysfs: Only accept read/write permissions for file attributes

For sysfs file attributes, only read and write permissions make sense.
Mask provided attribute permissions accordingly and send a warnin

sysfs: Only accept read/write permissions for file attributes

For sysfs file attributes, only read and write permissions make sense.
Mask provided attribute permissions accordingly and send a warning
to the console if invalid permission bits are set.

This patch is originally from Guenter [1] and includes the fixup
explained in the thread, that is printing permissions in octal format
and limiting the scope of attributes to SYSFS_PREALLOC | 0664.

[1] https://lkml.org/lkml/2015/1/19/599

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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sysfs: Use only return value from is_visible for the file mode

Up to now, is_visible can only be used to either remove visibility
of a file entirely or to add permissions, but not to reduce permissi

sysfs: Use only return value from is_visible for the file mode

Up to now, is_visible can only be used to either remove visibility
of a file entirely or to add permissions, but not to reduce permissions.
This makes it impossible, for example, to use DEVICE_ATTR_RW to define
file attributes and reduce permissions to read-only.

This behavior is undesirable and unnecessarily complicates code which
needs to reduce permissions; instead of just returning the desired
permissions, it has to ensure that the permissions in the attribute
variable declaration only reflect the minimal permissions ever needed.

Change semantics of is_visible to only use the permissions returned
from it instead of oring the returned value with the hard-coded
permissions.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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sysfs: fix warning when creating a sysfs group without attributes

When attempting to create a gropu without attrs, the warning prints the
name of the group. However, the check for name being a NULL

sysfs: fix warning when creating a sysfs group without attributes

When attempting to create a gropu without attrs, the warning prints the
name of the group. However, the check for name being a NULL pointer is
wrong: it uses the pointer to the name when it's NULL. Fix it to use
the name if present, otherwise just put an empty string.

Cc: Bruno Prémont <bonbons@linux-vserver.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Javi Merino <javi.merino@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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sysfs: fix attribute_group bin file path on removal

Cody Schafer already fixed binary file creation for attribute groups, see [1].
This patch makes the appropriate changes for binary file removal
of

sysfs: fix attribute_group bin file path on removal

Cody Schafer already fixed binary file creation for attribute groups, see [1].
This patch makes the appropriate changes for binary file removal
of attribute groups.
[1]: http://lkml.org/lkml/2014/2/27/832

Signed-off-by: Robert ABEL <rabel@cit-ec.uni-bielefeld.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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sysfs: create bin_attributes under the requested group

bin_attributes created/updated in create_files() (such as those listed
via (struct device).attribute_groups) were not placed under the
specifie

sysfs: create bin_attributes under the requested group

bin_attributes created/updated in create_files() (such as those listed
via (struct device).attribute_groups) were not placed under the
specified group, and instead appeared in the base kobj directory.

Fix this by making bin_attributes use creating code similar to normal
attributes.

A quick grep shows that no one is using bin_attrs in a named attribute
group yet, so we can do this without breaking anything in usespace.

Note that I do not add is_visible() support to
bin_attributes, though that could be done as well.

This is a copy of the patch already merged in Greg's tree.

Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

show more ...

sysfs: create bin_attributes under the requested group

bin_attributes created/updated in create_files() (such as those listed
via (struct device).attribute_groups) were not placed under the
specifie

sysfs: create bin_attributes under the requested group

bin_attributes created/updated in create_files() (such as those listed
via (struct device).attribute_groups) were not placed under the
specified group, and instead appeared in the base kobj directory.

Fix this by making bin_attributes use creating code similar to normal
attributes.

A quick grep shows that no one is using bin_attrs in a named attribute
group yet, so we can do this without breaking anything in usespace.

Note that I do not add is_visible() support to
bin_attributes, though that could be done as well.

Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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kernfs: add @mode to kernfs_create_dir[_ns]()

sysfs assumed 0755 for all newly created directories and kernfs
inherited it. This assumption is unnecessarily restrictive and
inconsistent with kernfs

kernfs: add @mode to kernfs_create_dir[_ns]()

sysfs assumed 0755 for all newly created directories and kernfs
inherited it. This assumption is unnecessarily restrictive and
inconsistent with kernfs_create_file[_ns](). This patch adds @mode
parameter to kernfs_create_dir[_ns]() and update uses in sysfs
accordingly. Among others, this will be useful for implementations of
the planned ->mkdir() method.

This patch doesn't introduce any behavior differences.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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