saner replacement for debugfs_rename()

Existing primitive has several problems:
1) calling conventions are clumsy - it returns a dentry reference
that is either identical to its second argument or

saner replacement for debugfs_rename()

Existing primitive has several problems:
1) calling conventions are clumsy - it returns a dentry reference
that is either identical to its second argument or is an ERR_PTR(-E...);
in both cases no refcount changes happen. Inconvenient for users and
bug-prone; it would be better to have it return 0 on success and -E... on
failure.
2) it allows cross-directory moves; however, no such caller have
ever materialized and considering the way debugfs is used, it's unlikely
to happen in the future. What's more, any such caller would have fun
issues to deal with wrt interplay with recursive removal. It also makes
the calling conventions clumsier...
3) tautological rename fails; the callers have no race-free way
to deal with that.
4) new name must have been formed by the caller; quite a few
callers have it done by sprintf/kasprintf/etc., ending up with considerable
boilerplate.

Proposed replacement: int debugfs_change_name(dentry, fmt, ...). All callers
convert to that easily, and it's simpler internally.

IMO debugfs_rename() should go; if we ever get a real-world use case for
cross-directory moves in debugfs, we can always look into the right way
to handle that.

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

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debugfs: take debugfs_short_fops definition out of ifdef

Signed-off-by: Al Viro <[email protected]>
Reviewed-by: Christian Brauner <[email protected]>
Link: https://lore.kernel.org/r/20250112

debugfs: take debugfs_short_fops definition out of ifdef

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: 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: 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: 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: 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: add debugfs_lookup_and_remove()

There is a very common pattern of using
debugfs_remove(debufs_lookup(..)) which results in a dentry leak of the
dentry that was looked up. Instead of having

debugfs: add debugfs_lookup_and_remove()

There is a very common pattern of using
debugfs_remove(debufs_lookup(..)) which results in a dentry leak of the
dentry that was looked up. Instead of having to open-code the correct
pattern of calling dput() on the dentry, create
debugfs_lookup_and_remove() to handle this pattern automatically and
properly without any memory leaks.

Cc: stable <[email protected]>
Reported-by: Kuyo Chang <[email protected]>
Tested-by: Kuyo Chang <[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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debugfs: Implement debugfs_create_str()

Implement debugfs_create_str() to easily display names and such in
debugfs.

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Greg Kr

debugfs: Implement debugfs_create_str()

Implement debugfs_create_str() to easily display names and such in
debugfs.

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Tested-by: Valentin Schneider <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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debugfs: remove return value of debugfs_create_devm_seqfile()

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

debugfs: remove return value of debugfs_create_devm_seqfile()

No one checks the return value of debugfs_create_devm_seqfile(), 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: make sure we can remove u32_array files cleanly

debugfs_create_u32_array() allocates a small structure to wrap
the data and size information about the array. If users ever
try to remove the

debugfs: make sure we can remove u32_array files cleanly

debugfs_create_u32_array() allocates a small structure to wrap
the data and size information about the array. If users ever
try to remove the file this leads to a leak since nothing ever
frees this wrapper.

That said there are no upstream users of debugfs_create_u32_array()
that'd remove a u32 array file (we only have one u32 array user in
CMA), so there is no real bug here.

Make callers pass a wrapper they allocated. This way the lifetime
management of the wrapper is on the caller, and we can avoid the
potential leak in debugfs.

CC: Chucheng Luo <[email protected]>
Signed-off-by: Jakub Kicinski <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

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debugfs: remove return value of debugfs_create_u32()

No one checks the return value of debugfs_create_u32(), as it's not
needed, so make the return value void, so that no one tries to do so in
the f

debugfs: remove return value of debugfs_create_u32()

No one checks the return value of debugfs_create_u32(), as it's not
needed, so make the return value void, so that no one tries to do so in
the future.

Signed-off-by: Greg Kroah-Hartman <[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_file_size()

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

debugfs: remove return value of debugfs_create_file_size()

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

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

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debugfs: regset32: Add Runtime PM support

Hardware registers of devices under control of power management cannot
be accessed at all times. If such a device is suspended, register
accesses may lead

debugfs: regset32: Add Runtime PM support

Hardware registers of devices under control of power management cannot
be accessed at all times. If such a device is suspended, register
accesses may lead to undefined behavior, like reading bogus values, or
causing exceptions or system lock-ups.

Extend struct debugfs_regset32 with an optional field to let device
drivers specify the device the registers in the set belong to. This
allows debugfs_show_regset32() to make sure the device is resumed while
its registers are being read.

Signed-off-by: Geert Uytterhoeven <[email protected]>
Reviewed-by: Niklas Söderlund <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Acked-by: Rafael J. Wysocki <[email protected]>
Signed-off-by: Herbert Xu <[email protected]>

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debugfs: remove return value of debugfs_create_regset32()

No one checks the return value of debugfs_create_regset32(), as it's not
needed, so make the return value void, so that no one tries to do s

debugfs: remove return value of debugfs_create_regset32()

No one checks the return value of debugfs_create_regset32(), 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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simple_recursive_removal(): kernel-side rm -rf for ramfs-style filesystems

two requirements: no file creations in IS_DEADDIR and no cross-directory
renames whatsoever.

Signed-off-by: Al Viro <viro@

simple_recursive_removal(): kernel-side rm -rf for ramfs-style filesystems

two requirements: no file creations in IS_DEADDIR and no cross-directory
renames whatsoever.

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

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debugfs: Fix !DEBUG_FS debugfs_create_automount

If DEBUG_FS=n, compile fails with the following error:

kernel/trace/trace.c: In function 'tracing_init_dentry':
kernel/trace/trace.c:8658:9: error: p

debugfs: Fix !DEBUG_FS debugfs_create_automount

If DEBUG_FS=n, compile fails with the following error:

kernel/trace/trace.c: In function 'tracing_init_dentry':
kernel/trace/trace.c:8658:9: error: passing argument 3 of 'debugfs_create_automount' from incompatible pointer type [-Werror=incompatible-pointer-types]
8658 | trace_automount, NULL);
| ^~~~~~~~~~~~~~~
| |
| struct vfsmount * (*)(struct dentry *, void *)
In file included from kernel/trace/trace.c:24:
./include/linux/debugfs.h:206:25: note: expected 'struct vfsmount * (*)(void *)' but argument is of type 'struct vfsmount * (*)(struct dentry *, void *)'
206 | struct vfsmount *(*f)(void *),
| ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~

Signed-off-by: Kusanagi Kouichi <[email protected]>
Link: https://lore.kernel.org/r/20191121102021787.MLMY.25002.ppp.dion.ne.jp@dmta0003.auone-net.jp
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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debugfs: Add debugfs_create_xul() for hexadecimal unsigned long

The existing debugfs_create_ulong() function supports objects of
type "unsigned long", which are 32-bit or 64-bit depending on the
pla

debugfs: Add debugfs_create_xul() for hexadecimal unsigned long

The existing debugfs_create_ulong() function supports objects of
type "unsigned long", which are 32-bit or 64-bit depending on the
platform, in decimal form. To format objects in hexadecimal, various
debugfs_create_x*() functions exist, but all of them take fixed-size
types.

Add a debugfs helper for "unsigned long" objects in hexadecimal format.
This avoids the need for users to open-code the same, or introduce
bugs when casting the value pointer to "u32 *" or "u64 *" to call
debugfs_create_x{32,64}().

Signed-off-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: remove return value of debugfs_create_atomic_t()

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

debugfs: remove return value of debugfs_create_atomic_t()

No one checks the return value of debugfs_create_atomic_t(), 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_x8()

No one checks the return value of debugfs_create_x8(), as it's not
needed, so make the return value void, so that no one tries to do so in
the fut

debugfs: remove return value of debugfs_create_x8()

No one checks the return value of debugfs_create_x8(), 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_x64()

No one checks the return value of debugfs_create_x64(), as it's not
needed, so make the return value void, so that no one tries to do so in
the f

debugfs: remove return value of debugfs_create_x64()

No one checks the return value of debugfs_create_x64(), 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_x32()

No one checks the return value of debugfs_create_x32(), as it's not
needed, so make the return value void, so that no one tries to do so in
the f

debugfs: remove return value of debugfs_create_x32()

No one checks the return value of debugfs_create_x32(), 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_x16()

No one checks the return value of debugfs_create_x16(), as it's not
needed, so make the return value void, so that no one tries to do so in
the f

debugfs: remove return value of debugfs_create_x16()

No one checks the return value of debugfs_create_x16(), 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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