kernfs: Use RCU to access kernfs_node::parent.

kernfs_rename_lock is used to obtain stable kernfs_node::{name|parent}
pointer. This is a preparation to access kernfs_node::parent under RCU
and ensur

kernfs: Use RCU to access kernfs_node::parent.

kernfs_rename_lock is used to obtain stable kernfs_node::{name|parent}
pointer. This is a preparation to access kernfs_node::parent under RCU
and ensure that the pointer remains stable under the RCU lifetime
guarantees.

For a complete path, as it is done in kernfs_path_from_node(), the
kernfs_rename_lock is still required in order to obtain a stable parent
relationship while computing the relevant node depth. This must not
change while the nodes are inspected in order to build the path.
If the kernfs user never moves the nodes (changes the parent) then the
kernfs_rename_lock is not required and the RCU guarantees are
sufficient. This "restriction" can be set with
KERNFS_ROOT_INVARIANT_PARENT. Otherwise the lock is required.

Rename kernfs_node::parent to kernfs_node::__parent to denote the RCU
access and use RCU accessor while accessing the node.
Make cgroup use KERNFS_ROOT_INVARIANT_PARENT since the parent here can
not change.

Acked-by: Tejun Heo <[email protected]>
Cc: Yonghong Song <[email protected]>
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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sysfs: constify bin_attribute argument of sysfs_bin_attr_simple_read()

Most users use this function through the BIN_ATTR_SIMPLE* macros,
they can handle the switch transparently.
Also adapt the two

sysfs: constify bin_attribute argument of sysfs_bin_attr_simple_read()

Most users use this function through the BIN_ATTR_SIMPLE* macros,
they can handle the switch transparently.
Also adapt the two non-macro users in the same change.

Signed-off-by: Thomas Weißschuh <[email protected]>
Acked-by: Madhavan Srinivasan <[email protected]>
Reviewed-by: Mahesh Salgaonkar <[email protected]>
Tested-by: Aditya Gupta <[email protected]>
Link: https://lore.kernel.org/r/20241228-sysfs-const-bin_attr-simple-v2-1-7c6f3f1767a3@weissschuh.net
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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sysfs: bin_attribute: add const read/write callback variants

To make it possible to put struct bin_attribute into read-only memory,
the sysfs core has to stop passing mutable pointers to the read()

sysfs: bin_attribute: add const read/write callback variants

To make it possible to put struct bin_attribute into read-only memory,
the sysfs core has to stop passing mutable pointers to the read() and
write() callbacks.
As there are numerous implementors of these callbacks throughout the
tree it's not possible to change all of them at once.
To enable a step-by-step transition, add new variants of the read() and
write() callbacks which differ only in the constness of the struct
bin_attribute argument.

As most binary attributes are defined through macros, extend these
macros to transparently handle both variants of callbacks to minimize
the churn during the transition.
As soon as all handlers are switch to the const variant, the non-const
one can be removed together with the transition machinery.

Signed-off-by: Thomas Weißschuh <[email protected]>
Acked-by: Krzysztof Wilczyński <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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sysfs: explicitly pass size to sysfs_add_bin_file_mode_ns()

Upcoming changes to the sysfs core require the size of the created file
to be overridable by the caller.
Add a parameter to enable this.
F

sysfs: explicitly pass size to sysfs_add_bin_file_mode_ns()

Upcoming changes to the sysfs core require the size of the created file
to be overridable by the caller.
Add a parameter to enable this.
For now keep using attr->size in all cases.

Signed-off-by: Thomas Weißschuh <[email protected]>
Acked-by: Krzysztof Wilczyński <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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sysfs: Add sysfs_bin_attr_simple_read() helper

When drivers expose a bin_attribute in sysfs which is backed by a buffer
in memory, a common pattern is to set the @private and @size members in
struct

sysfs: Add sysfs_bin_attr_simple_read() helper

When drivers expose a bin_attribute in sysfs which is backed by a buffer
in memory, a common pattern is to set the @private and @size members in
struct bin_attribute to the buffer's location and size.

The ->read() callback then merely consists of a single memcpy() call.
It's not even necessary to perform bounds checks as these are already
handled by sysfs_kf_bin_read().

However each driver is so far providing its own ->read() implementation.
The pattern is sufficiently frequent to merit a public helper, so add
sysfs_bin_attr_simple_read() as well as BIN_ATTR_SIMPLE_RO() and
BIN_ATTR_SIMPLE_ADMIN_RO() macros to ease declaration of such
bin_attributes and reduce LoC and .text section size.

Signed-off-by: Lukas Wunner <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Acked-by: Rafael J. Wysocki <[email protected]>
Acked-by: Ard Biesheuvel <[email protected]>
Link: https://lore.kernel.org/r/5ed62b197a442ec6db53d8746d9d806dd0576e2d.1712410202.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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fs: sysfs: Fix reference leak in sysfs_break_active_protection()

The sysfs_break_active_protection() routine has an obvious reference
leak in its error path. If the call to kernfs_find_and_get() fa

fs: sysfs: Fix reference leak in sysfs_break_active_protection()

The sysfs_break_active_protection() routine has an obvious reference
leak in its error path. If the call to kernfs_find_and_get() fails then
kn will be NULL, so the companion sysfs_unbreak_active_protection()
routine won't get called (and would only cause an access violation by
trying to dereference kn->parent if it was called). As a result, the
reference to kobj acquired at the start of the function will never be
released.

Fix the leak by adding an explicit kobject_put() call when kn is NULL.

Signed-off-by: Alan Stern <[email protected]>
Fixes: 2afc9166f79b ("scsi: sysfs: Introduce sysfs_{un,}break_active_protection()")
Cc: Bart Van Assche <[email protected]>
Cc: [email protected]
Reviewed-by: Bart Van Assche <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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kernfs: sysfs: support custom llseek method for sysfs entries

As of now, seeking in sysfs files is handled by generic_file_llseek().
There are situations where one may want to customize seeking logi

kernfs: sysfs: support custom llseek method for sysfs entries

As of now, seeking in sysfs files is handled by generic_file_llseek().
There are situations where one may want to customize seeking logic:

- Many sysfs entries are fixed files while generic_file_llseek() accepts
past-the-end positions. Not only being useless by itself, this
also means a bug in userspace code will trigger not at lseek(), but at
some later point making debugging harder.
- generic_file_llseek() relies on f_mapping->host to get the file size
which might not be correct for all sysfs entries.
See commit 636b21b50152 ("PCI: Revoke mappings like devmem") as an example.

Implement llseek method to override this behavior at sysfs attribute
level. The method is optional, and if it is absent,
generic_file_llseek() is called to preserve backwards compatibility.

Signed-off-by: Valentine Sinitsyn <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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kobject: kobj_type: remove default_attrs

Now that all in-kernel users of default_attrs for the kobj_type are gone
and converted to properly use the default_groups pointer instead, it can
be safely r

kobject: kobj_type: remove default_attrs

Now that all in-kernel users of default_attrs for the kobj_type are gone
and converted to properly use the default_groups pointer instead, it can
be safely removed.

There is one standard way to create sysfs files in a kobj_type, and not
two like before, causing confusion as to which should be used.

Cc: "Rafael J. Wysocki" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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sysfs: simplify sysfs_kf_seq_show

Contrary to the comment ->show is never called from lseek for sysfs,
given that sysfs does not use seq_lseek. So remove the NULL ->show
case and just WARN and retu

sysfs: simplify sysfs_kf_seq_show

Contrary to the comment ->show is never called from lseek for sysfs,
given that sysfs does not use seq_lseek. So remove the NULL ->show
case and just WARN and return an error if some future code path ends
up here.

Acked-by: Tejun Heo <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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sysfs: refactor sysfs_add_file_mode_ns

Regroup the code so that preallocated attributes and normal attributes are
handled in clearly separate blocks.

Acked-by: Christian Brauner <christian.brauner@

sysfs: refactor sysfs_add_file_mode_ns

Regroup the code so that preallocated attributes and normal attributes are
handled in clearly separate blocks.

Acked-by: Christian Brauner <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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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 <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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sysfs: Rename struct bin_attribute member to f_mapping

There are two users of iomem_get_mapping(), the struct file and struct
bin_attribute. The former has a member called "f_mapping" and the
latte

sysfs: Rename struct bin_attribute member to f_mapping

There are two users of iomem_get_mapping(), the struct file and struct
bin_attribute. The former has a member called "f_mapping" and the
latter has a member called "mapping", and both are poniters to struct
address_space.

Rename struct bin_attribute member to "f_mapping" to keep both meaning
and the usage consistent with other users of iomem_get_mapping().

Acked-by: Bjorn Helgaas <[email protected]>
Signed-off-by: Krzysztof Wilczyński <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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sysfs: Invoke iomem_get_mapping() from the sysfs open callback

Defer invocation of the iomem_get_mapping() to the sysfs open callback
so that it can be executed as needed when the binary sysfs objec

sysfs: Invoke iomem_get_mapping() from the sysfs open callback

Defer invocation of the iomem_get_mapping() to the sysfs open callback
so that it can be executed as needed when the binary sysfs object has
been accessed.

To do that, convert the "mapping" member of the struct bin_attribute
from a pointer to the struct address_space into a function pointer with
a signature that requires the same return type, and then updates the
sysfs_kf_bin_open() to invoke provided function should the function
pointer be valid.

Also, convert every invocation of iomem_get_mapping() into a function
pointer assignment, therefore allowing for the iomem_get_mapping()
invocation to be deferred to when the sysfs open callback runs.

Thus, this change removes the need for the fs_initcalls to complete
before any other sub-system that uses the iomem_get_mapping() would be
able to invoke it safely without leading to a failure and an Oops
related to an invalid iomem_get_mapping() access.

Suggested-by: Dan Williams <[email protected]>
Reviewed-by: Dan Williams <[email protected]>
Acked-by: Bjorn Helgaas <[email protected]>
Signed-off-by: Dan Williams <[email protected]>
Signed-off-by: Krzysztof Wilczyński <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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sysfs: Support zapping of binary attr mmaps

We want to be able to revoke pci mmaps so that the same access rules
applies as for /dev/kmem. Revoke support for devmem was added in
3234ac664a87 ("/dev/

sysfs: Support zapping of binary attr mmaps

We want to be able to revoke pci mmaps so that the same access rules
applies as for /dev/kmem. Revoke support for devmem was added in
3234ac664a87 ("/dev/mem: Revoke mappings when a driver claims the
region").

The simplest way to achieve this is by having the same filp->f_mapping
for all mappings, so that unmap_mapping_range can find them all, no
matter through which file they've been created. Since this must be set
at open time we need sysfs support for this.

Add an optional mapping parameter bin_attr, which is only consulted
when there's also an mmap callback, since without mmap support
allowing to adjust the ->f_mapping makes no sense.

Reviewed-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Daniel Vetter <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: Jérôme Glisse <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: Bjorn Helgaas <[email protected]>
Cc: [email protected]
Cc: Greg Kroah-Hartman <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Sourabh Jain <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Mauro Carvalho Chehab <[email protected]>
Cc: Nayna Jain <[email protected]>
Signed-off-by: Daniel Vetter <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

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sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output

Output defects can exist in sysfs content using sprintf and snprintf.

sprintf does not know the PAGE_SIZE maximum of the temporary buf

sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output

Output defects can exist in sysfs content using sprintf and snprintf.

sprintf does not know the PAGE_SIZE maximum of the temporary buffer
used for outputting sysfs content and it's possible to overrun the
PAGE_SIZE buffer length.

Add a generic sysfs_emit function that knows that the size of the
temporary buffer and ensures that no overrun is done.

Add a generic sysfs_emit_at function that can be used in multiple
call situations that also ensures that no overrun is done.

Validate the output buffer argument to be page aligned.
Validate the offset len argument to be within the PAGE_SIZE buf.

Signed-off-by: Joe Perches <[email protected]>
Link: https://lore.kernel.org/r/884235202216d464d61ee975f7465332c86f76b2.1600285923.git.joe@perches.com
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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sysfs: export sysfs_remove_file_self()

Function is going to be used in transport over RDMA module in subsequent
patches, so export it to GPL modules.

Link: https://lore.kernel.org/r/20200511135131.

sysfs: export sysfs_remove_file_self()

Function is going to be used in transport over RDMA module in subsequent
patches, so export it to GPL modules.

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Roman Pen <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Cc: [email protected]
[jwang: extend the commit message]
Signed-off-by: Jack Wang <[email protected]>
Reviewed-by: Bart Van Assche <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>

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docs: filesystems: fix renamed references

Some filesystem references got broken by a previous patch
series I submitted. Address those.

Signed-off-by: Mauro Carvalho Chehab <[email protected]

docs: filesystems: fix renamed references

Some filesystem references got broken by a previous patch
series I submitted. Address those.

Signed-off-by: Mauro Carvalho Chehab <[email protected]>
Acked-by: David Sterba <[email protected]> # fs/affs/Kconfig
Link: https://lore.kernel.org/r/57318c53008dbda7f6f4a5a9e5787f4d37e8565a.1586881715.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <[email protected]>

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sysfs: add sysfs_change_owner()

Add a helper to change the owner of sysfs objects.
This function will be used to correctly account for kobject ownership
changes, e.g. when moving network devices bet

sysfs: add sysfs_change_owner()

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

This mirrors how a kobject is added through driver core which in its guts is
done via kobject_add_internal() which in summary creates the main directory via
create_dir(), populates that directory with the groups associated with the
ktype of the kobject (if any) and populates the directory with the basic
attributes associated with the ktype of the kobject (if any). These are the
basic steps that are associated with adding a kobject in sysfs.
Any additional properties are added by the specific subsystem itself (not by
driver core) after it has registered the device. So for the example of network
devices, a network device will e.g. register a queue subdirectory under the
basic sysfs directory for the network device and than further subdirectories
within that queues subdirectory. But that is all specific to network devices
and they call the corresponding sysfs functions to do that directly when they
create those queue objects. So anything that a subsystem adds outside of what
driver core does must also be changed by it (That's already true for removal of
files it created outside of driver core.) and it's the same for ownership
changes.

Reviewed-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Christian Brauner <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

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sysfs: add sysfs_link_change_owner()

Add a helper to change the owner of a sysfs link.
This function will be used to correctly account for kobject ownership
changes, e.g. when moving network devices

sysfs: add sysfs_link_change_owner()

Add a helper to change the owner of a sysfs link.
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 <[email protected]>
Signed-off-by: Christian Brauner <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

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sysfs: add sysfs_file_change_owner()

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

sysfs: add sysfs_file_change_owner()

Add helpers to change the owner of a sysfs files.
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 <[email protected]>
Signed-off-by: Christian Brauner <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

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sysfs: remove unused include of kernfs-internal.h

This include is not needed (fs/sysfs/file.c builds just fine without
it). Remove it.

Cc: Tejun Heo <[email protected]>
Signed-off-by: Ondrej Mosnacek <

sysfs: remove unused include of kernfs-internal.h

This include is not needed (fs/sysfs/file.c builds just fine without
it). Remove it.

Cc: Tejun Heo <[email protected]>
Signed-off-by: Ondrej Mosnacek <[email protected]>
Reviewed-by: Rafael J. Wysocki <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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sysfs: fix blank line coding style warning

Fixed a coding style issue.

Signed-off-by: Stephen Martin <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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 <[email protected]>
Reviewed-by: Rafael J. Wysocki <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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sysfs: constify sysfs create/remove files harder

Let the passed in array be const (and thus placed in rodata) instead of
a mutable array of const pointers.

Cc: Greg Kroah-Hartman <gregkh@linuxfound

sysfs: constify sysfs create/remove files harder

Let the passed in array be const (and thus placed in rodata) instead of
a mutable array of const pointers.

Cc: Greg Kroah-Hartman <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Reviewed-by: Rafael J. Wysocki <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Jani Nikula <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

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scsi: sysfs: Introduce sysfs_{un,}break_active_protection()

Introduce these two functions and export them such that the next patch
can add calls to these functions from the SCSI core.

Signed-off-by

scsi: sysfs: Introduce sysfs_{un,}break_active_protection()

Introduce these two functions and export them such that the next patch
can add calls to these functions from the SCSI core.

Signed-off-by: Bart Van Assche <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Acked-by: Greg Kroah-Hartman <[email protected]>
Cc: <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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