debugfs: Fix the missing initializations in __debugfs_file_get()

both method table pointers in debugfs_fsdata need to be initialized,
obviously, and calculating the bitmap of present methods would a

debugfs: Fix the missing initializations in __debugfs_file_get()

both method table pointers in debugfs_fsdata need to be initialized,
obviously, and calculating the bitmap of present methods would also
go better if we start with initialized state.

Fixes: 41a0ecc0997c ("debugfs: get rid of dynamically allocation proxy_ops")
Signed-off-by: Al Viro <[email protected]>
Link: https://lore.kernel.org/r/20250129191937.GR1977892@ZenIV
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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debugfs: allow to store an additional opaque pointer at file creation

Set by debugfs_create_file_aux(name, mode, parent, data, aux, fops).
Plain debugfs_create_file() has it set to NULL.
Accessed by

debugfs: allow to store an additional opaque pointer at file creation

Set by debugfs_create_file_aux(name, mode, parent, data, aux, fops).
Plain debugfs_create_file() has it set to NULL.
Accessed by debugfs_get_aux(file).

Convenience macros for numeric opaque data - debugfs_create_file_aux_num
and debugfs_get_aux_num, resp.

Signed-off-by: Al Viro <[email protected]>
Reviewed-by: Christian Brauner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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debugfs: don't mess with bits in ->d_fsdata

The reason we need that crap is the dual use ->d_fsdata has there -
it's both holding a debugfs_fsdata reference after the first
debugfs_file_get() (actua

debugfs: don't mess with bits in ->d_fsdata

The reason we need that crap is the dual use ->d_fsdata has there -
it's both holding a debugfs_fsdata reference after the first
debugfs_file_get() (actually, after the call of proxy ->open())
*and* it serves as a place to stash a reference to real file_operations
from object creation to the first open. Oh, and it's triple use,
actually - that stashed reference might be to debugfs_short_fops.

Bugger that for a game of solidiers - just put the operations
reference into debugfs-private augmentation of inode. And split
debugfs_full_file_operations into full and short cases, so that
debugfs_get_file() could tell one from another.

Voila - ->d_fsdata holds NULL until the first (successful) debugfs_get_file()
and a reference to struct debugfs_fsdata afterwards.

Signed-off-by: Al Viro <[email protected]>
Reviewed-by: Christian Brauner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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debugfs: get rid of dynamically allocation proxy_ops

All it takes is having full_proxy_open() collect the information
about available methods and store it in debugfs_fsdata.

Wrappers are called onl

debugfs: get rid of dynamically allocation proxy_ops

All it takes is having full_proxy_open() collect the information
about available methods and store it in debugfs_fsdata.

Wrappers are called only after full_proxy_open() has succeeded
calling debugfs_get_file(), so they are guaranteed to have
->d_fsdata already pointing to debugfs_fsdata.

As the result, they can check if method is absent and bugger off
early, without any atomic operations, etc. - same effect as what
we'd have from NULL method. Which makes the entire proxy_fops
contents unconditional, making it completely pointless - we can
just put those methods (unconditionally) into
debugfs_full_proxy_file_operations and forget about dynamic
allocation, replace_fops, etc.

Signed-off-by: Al Viro <[email protected]>
Reviewed-by: Christian Brauner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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fs: debugfs: fix open proxy for unsafe files

In the previous commit referenced below, I had to split
the short fops handling into different proxy fops. This
necessitated knowing out-of-band whether

fs: debugfs: fix open proxy for unsafe files

In the previous commit referenced below, I had to split
the short fops handling into different proxy fops. This
necessitated knowing out-of-band whether or not the ops
are short or full, when attempting to convert from fops
to allocated fsdata.

Unfortunately, I only converted full_proxy_open() which
is used for the new full_proxy_open_regular() and
full_proxy_open_short(), but forgot about the call in
open_proxy_open(), used for debugfs_create_file_unsafe().

Fix that, it never has short fops.

Fixes: f8f25893a477 ("fs: debugfs: differentiate short fops with proxy ops")
Reported-by: Suresh Kumar Kurmi <[email protected]>
Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/oe-lkp/[email protected]
Reported-by: Venkat Rao Bagalkote <[email protected]>
Signed-off-by: Johannes Berg <[email protected]>
Link: https://lore.kernel.org/r/20250110085826.cd74f3b7a36b.I430c79c82ec3f954c2ff9665753bf6ac9e63eef8@changeid
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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fs: debugfs: differentiate short fops with proxy ops

Geert reported that my previous short fops debugfs changes
broke m68k, because it only has mandatory alignement of two,
so we can't stash the "is

fs: debugfs: differentiate short fops with proxy ops

Geert reported that my previous short fops debugfs changes
broke m68k, because it only has mandatory alignement of two,
so we can't stash the "is it short" information into the
pointer (as we already did with the "is it real" bit.)

Instead, exploit the fact that debugfs_file_get() called on
an already open file will already find that the fsdata is
no longer the real fops but rather the allocated data that
already distinguishes full/short ops, so only open() needs
to be able to distinguish. We can achieve that by using two
different open functions.

Unfortunately this requires another set of full file ops,
increasing the size by 536 bytes (x86-64), but that's still
a reasonable trade-off given that only converting some of
the wireless stack gained over 28k. This brings the total
cost of this to around 1k, for wins of 28k (all x86-64).

Reported-and-tested-by: Geert Uytterhoeven <[email protected]>
Link: https://lore.kernel.org/CAMuHMdWu_9-L2Te101w8hU7H_2yobJFPXSwwUmGHSJfaPWDKiQ@mail.gmail.com
Fixes: 8dc6d81c6b2a ("debugfs: add small file operations for most files")
Signed-off-by: Johannes Berg <[email protected]>
Tested-by: Geert Uytterhoeven <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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debugfs: add small file operations for most files

As struct file_operations is really big, but (most) debugfs
files only use simple_open, read, write and perhaps seek, and
don't need anything else,

debugfs: add small file operations for most files

As struct file_operations is really big, but (most) debugfs
files only use simple_open, read, write and perhaps seek, and
don't need anything else, this wastes a lot of space for NULL
pointers.

Add a struct debugfs_short_fops and some bookkeeping code in
debugfs so that users can use that with debugfs_create_file()
using _Generic to figure out which function to use.

Converting mac80211 to use it where possible saves quite a
bit of space:

1010127 205064 1220 1216411 128f9b net/mac80211/mac80211.ko (before)
981199 205064 1220 1187483 121e9b net/mac80211/mac80211.ko (after)
-------
-28928 = ~28KiB

With a marginal space cost in debugfs:

8701 550 16 9267 2433 fs/debugfs/inode.o (before)
25233 325 32 25590 63f6 fs/debugfs/file.o (before)
8914 558 16 9488 2510 fs/debugfs/inode.o (after)
25380 325 32 25737 6489 fs/debugfs/file.o (after)
---------------
+360 +8

(All on x86-64)

A simple spatch suggests there are more than 300 instances,
not even counting the ones hidden in macros like in mac80211,
that could be trivially converted, for additional savings of
about 240 bytes for each.

Reviewed-by: Greg Kroah-Hartman <[email protected]>
Link: https://patch.msgid.link/20241022151838.26f9925fb959.Ia80b55e934bbfc45ce0df42a3233d34b35508046@changeid
Signed-off-by: Johannes Berg <[email protected]>

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[tree-wide] finally take no_llseek out

no_llseek had been defined to NULL two years ago, in commit 868941b14441
("fs: remove no_llseek")

To quote that commit,

At -rc1 we'll need do a mechanical

[tree-wide] finally take no_llseek out

no_llseek had been defined to NULL two years ago, in commit 868941b14441
("fs: remove no_llseek")

To quote that commit,

At -rc1 we'll need do a mechanical removal of no_llseek -

git grep -l -w no_llseek | grep -v porting.rst | while read i; do
sed -i '/\<no_llseek\>/d' $i
done

would do it.

Unfortunately, that hadn't been done. Linus, could you do that now, so
that we could finally put that thing to rest? All instances are of the
form
.llseek = no_llseek,
so it's obviously safe.

Signed-off-by: Al Viro <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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debugfs: initialize cancellations earlier

Tetsuo Handa pointed out that in the (now reverted)
lockdep commit I initialized the data too late. The
same is true for the cancellation data, it must be
i

debugfs: initialize cancellations earlier

Tetsuo Handa pointed out that in the (now reverted)
lockdep commit I initialized the data too late. The
same is true for the cancellation data, it must be
initialized before the cmpxchg(), otherwise it may
be done twice and possibly even overwriting data in
there already when there's a race. Fix that, which
also requires destroying the mutex in case we lost
the race.

Fixes: 8c88a474357e ("debugfs: add API to allow debugfs operations cancellation")
Reported-by: Tetsuo Handa <[email protected]>
Signed-off-by: Johannes Berg <[email protected]>
Link: https://lore.kernel.org/r/20231221150444.1e47a0377f80.If7e8ba721ba2956f12c6e8405e7d61e154aa7ae7@changeid
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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Revert "debugfs: annotate debugfs handlers vs. removal with lockdep"

This reverts commit f4acfcd4deb1 ("debugfs: annotate debugfs handlers
vs. removal with lockdep"), it appears to have false positi

Revert "debugfs: annotate debugfs handlers vs. removal with lockdep"

This reverts commit f4acfcd4deb1 ("debugfs: annotate debugfs handlers
vs. removal with lockdep"), it appears to have false positives and
really shouldn't have been in the -rc series with the fixes anyway.

Signed-off-by: Johannes Berg <[email protected]>
Link: https://lore.kernel.org/r/20231202114936.fd55431ab160.I911aa53abeeca138126f690d383a89b13eb05667@changeid
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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debugfs: add API to allow debugfs operations cancellation

In some cases there might be longer-running hardware accesses
in debugfs files, or attempts to acquire locks, and we want
to still be able t

debugfs: add API to allow debugfs operations cancellation

In some cases there might be longer-running hardware accesses
in debugfs files, or attempts to acquire locks, and we want
to still be able to quickly remove the files.

Introduce a cancellations API to use inside the debugfs handler
functions to be able to cancel such operations on a per-file
basis.

Acked-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Johannes Berg <[email protected]>

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debugfs: annotate debugfs handlers vs. removal with lockdep

When you take a lock in a debugfs handler but also try
to remove the debugfs file under that lock, things can
deadlock since the removal h

debugfs: annotate debugfs handlers vs. removal with lockdep

When you take a lock in a debugfs handler but also try
to remove the debugfs file under that lock, things can
deadlock since the removal has to wait for all users
to finish.

Add lockdep annotations in debugfs_file_get()/_put()
to catch such issues.

Acked-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Johannes Berg <[email protected]>

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debugfs: fix automount d_fsdata usage

debugfs_create_automount() stores a function pointer in d_fsdata,
but since commit 7c8d469877b1 ("debugfs: add support for more
elaborate ->d_fsdata") debugfs_r

debugfs: fix automount d_fsdata usage

debugfs_create_automount() stores a function pointer in d_fsdata,
but since commit 7c8d469877b1 ("debugfs: add support for more
elaborate ->d_fsdata") debugfs_release_dentry() will free it, now
conditionally on DEBUGFS_FSDATA_IS_REAL_FOPS_BIT, but that's not
set for the function pointer in automount. As a result, removing
an automount dentry would attempt to free the function pointer.
Luckily, the only user of this (tracing) never removes it.

Nevertheless, it's safer if we just handle the fsdata in one way,
namely either DEBUGFS_FSDATA_IS_REAL_FOPS_BIT or allocated. Thus,
change the automount to allocate it, and use the real_fops in the
data to indicate whether or not automount is filled, rather than
adding a type tag. At least for now this isn't actually needed,
but the next changes will require it.

Also check in debugfs_file_get() that it gets only called
on regular files, just to make things clearer.

Acked-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Johannes Berg <[email protected]>

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fs: debugfs: Add write functionality to debugfs blobs

Currently, debugfs_create_blob() creates read-only debugfs binary blob
files.

In some cases, however, userspace tools need to write variable le

fs: debugfs: Add write functionality to debugfs blobs

Currently, debugfs_create_blob() creates read-only debugfs binary blob
files.

In some cases, however, userspace tools need to write variable length
data structures into predetermined memory addresses. An example is when
injecting Vendor-defined error types through the einj module. In such
cases, the functionality to write to these blob files in debugfs would
be desired since the mapping aspect can be handled within the modules
with userspace tools only needing to write into the blob files.

Implement a write callback to enable writing to these blob files, created
in debugfs, by owners only.

Signed-off-by: Avadhut Naik <[email protected]>
Reviewed-by: Alexey Kardashevskiy <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Reviewed-by: Tony Luck <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>

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debugfs: Fix __rcu type comparison warning

Sparse reports the following:

fs/debugfs/file.c:942:9: sparse: sparse: incompatible types in comparison expression (different address spaces):
fs/debugfs/

debugfs: Fix __rcu type comparison warning

Sparse reports the following:

fs/debugfs/file.c:942:9: sparse: sparse: incompatible types in comparison expression (different address spaces):
fs/debugfs/file.c:942:9: sparse: char [noderef] __rcu *
fs/debugfs/file.c:942:9: sparse: char *

rcu_assign_pointer() expects that it's assigning to pointers annotated
with __rcu. We can't annotate the generic struct file::private_data, so
cast it instead.

Fixes: 86b5488121db ("debugfs: Add write support to debugfs_create_str()")
Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
Signed-off-by: Mike Tipton <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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debugfs: Add write support to debugfs_create_str()

Currently, debugfs_create_str() only supports reading strings from
debugfs. Add support for writing them as well.

Based on original implementation

debugfs: Add write support to debugfs_create_str()

Currently, debugfs_create_str() only supports reading strings from
debugfs. Add support for writing them as well.

Based on original implementation by Peter Zijlstra [0]. Write support
was present in the initial patch version, but dropped in v2 due to lack
of users. We have a user now, so reintroduce it.

[0] https://lore.kernel.org/all/YF3Hv5zXb%[email protected]/

Signed-off-by: Mike Tipton <[email protected]>
Acked-by: Greg Kroah-Hartman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Georgi Djakov <[email protected]>

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debugfs: Correct the 'debugfs_create_str' docs

The documentation of the 'debugfs_create_str' says that the function
returns a pointer to a dentry created, or an ERR_PTR in case of error.
Actually, t

debugfs: Correct the 'debugfs_create_str' docs

The documentation of the 'debugfs_create_str' says that the function
returns a pointer to a dentry created, or an ERR_PTR in case of error.
Actually, this is not true: this function doesn't return anything at all.
Correct the documentation correspondingly.

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

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debugfs: Export debugfs_create_str symbol

Needed by SCMI Raw mode support when compiled as a loadable module.

Cc: Greg Kroah-Hartman <[email protected]>
Cc: "Rafael J. Wysocki" <rafael@ker

debugfs: Export debugfs_create_str symbol

Needed by SCMI Raw mode support when compiled as a loadable module.

Cc: Greg Kroah-Hartman <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Signed-off-by: Cristian Marussi <[email protected]>
Tested-by: Florian Fainelli <[email protected]>
Tested-by: Vincent Guittot <[email protected]>
Acked-by: Greg Kroah-Hartman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Sudeep Holla <[email protected]>

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debugfs: fix error when writing negative value to atomic_t debugfs file

The simple attribute files do not accept a negative value since the commit
488dac0c9237 ("libfs: fix error cast of negative va

debugfs: fix error when writing negative value to atomic_t debugfs file

The simple attribute files do not accept a negative value since the commit
488dac0c9237 ("libfs: fix error cast of negative value in
simple_attr_write()"), so we have to use a 64-bit value to write a
negative value for a debugfs file created by debugfs_create_atomic_t().

This restores the previous behaviour by introducing
DEFINE_DEBUGFS_ATTRIBUTE_SIGNED for a signed value.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 488dac0c9237 ("libfs: fix error cast of negative value in simple_attr_write()")
Signed-off-by: Akinobu Mita <[email protected]>
Reported-by: Zhao Gongyi <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Rafael J. Wysocki <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Wei Yongjun <[email protected]>
Cc: Yicong Yang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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debugfs: use DEFINE_SHOW_ATTRIBUTE to define debugfs_regset32_fops

Use DEFINE_SHOW_ATTRIBUTE helper macro to simplify the code.

Signed-off-by: ChenXiaoSong <[email protected]>
Link: https://

debugfs: use DEFINE_SHOW_ATTRIBUTE to define debugfs_regset32_fops

Use DEFINE_SHOW_ATTRIBUTE helper macro to simplify the code.

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

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debugfs: lockdown: Allow reading debugfs files that are not world readable

When the kernel is locked down the kernel allows reading only debugfs
files with mode 444. Mode 400 is also valid but is no

debugfs: lockdown: Allow reading debugfs files that are not world readable

When the kernel is locked down the kernel allows reading only debugfs
files with mode 444. Mode 400 is also valid but is not allowed.

Make the 444 into a mask.

Fixes: 5496197f9b08 ("debugfs: Restrict debugfs when the kernel is locked down")
Signed-off-by: Michal Suchanek <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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debugfs: Return error during {full/open}_proxy_open() on rmmod

If a kernel module gets unloaded then it printed report about a leak before
commit 275678e7a9be ("debugfs: Check module state before wa

debugfs: Return error during {full/open}_proxy_open() on rmmod

If a kernel module gets unloaded then it printed report about a leak before
commit 275678e7a9be ("debugfs: Check module state before warning in
{full/open}_proxy_open()"). An additional check was added in this commit to
avoid this printing. But it was forgotten that the function must return an
error in this case because it was not actually opened.

As result, the systems started to crash or to hang when a module was
unloaded while something was trying to open a file.

Fixes: 275678e7a9be ("debugfs: Check module state before warning in {full/open}_proxy_open()")
Cc: Taehee Yoo <[email protected]>
Reported-by: Mário Lopes <[email protected]>
Signed-off-by: Sven Eckelmann <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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debugfs: Fix debugfs_read_file_str()

Read the entire size of the buffer, including the trailing new line
character.
Discovered while reading the sched domain names of CPU0:

before:

cat /sys/kernel

debugfs: Fix debugfs_read_file_str()

Read the entire size of the buffer, including the trailing new line
character.
Discovered while reading the sched domain names of CPU0:

before:

cat /sys/kernel/debug/sched/domains/cpu0/domain*/name
SMTMCDIE

after:

cat /sys/kernel/debug/sched/domains/cpu0/domain*/name
SMT
MC
DIE

Fixes: 9af0440ec86eb ("debugfs: Implement debugfs_create_str()")
Reviewed-by: Steven Rostedt (VMware) <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Dietmar Eggemann <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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debugfs: remove return value of debugfs_create_ulong()

No one checks the return value of debugfs_create_ulong(), as it's not
needed, so make the return value void, so that no one tries to do so in
t

debugfs: remove return value of debugfs_create_ulong()

No one checks the return value of debugfs_create_ulong(), as it's not
needed, so make the return value void, so that no one tries to do so in
the future.

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

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debugfs: remove return value of debugfs_create_bool()

No one checks the return value of debugfs_create_bool(), as it's not
needed, so make the return value void, so that no one tries to do so in
the

debugfs: remove return value of debugfs_create_bool()

No one checks the return value of debugfs_create_bool(), as it's not
needed, so make the return value void, so that no one tries to do so in
the future.

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

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