linux.git/fs/debugfs/file.c, branch v6.13

fs: debugfs: fix open proxy for unsafe files

2025-01-10T08:41:53+00:00

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 
Reported-by: kernel test robot 
Closes: https://lore.kernel.org/oe-lkp/202501101055.bb8bf3e7-lkp@intel.com
Reported-by: Venkat Rao Bagalkote 
Signed-off-by: Johannes Berg 
Link: https://lore.kernel.org/r/20250110085826.cd74f3b7a36b.I430c79c82ec3f954c2ff9665753bf6ac9e63eef8@changeid
Signed-off-by: Greg Kroah-Hartman

fs: debugfs: differentiate short fops with proxy ops

2025-01-07T15:20:08+00:00

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 
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 
Tested-by: Geert Uytterhoeven 
Link: https://lore.kernel.org/r/20241129121536.30989-2-johannes@sipsolutions.net
Signed-off-by: Greg Kroah-Hartman

debugfs: add small file operations for most files

2024-10-23T14:47:01+00:00

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 
Link: https://patch.msgid.link/20241022151838.26f9925fb959.Ia80b55e934bbfc45ce0df42a3233d34b35508046@changeid
Signed-off-by: Johannes Berg

[tree-wide] finally take no_llseek out

2024-09-27T15:18:43+00:00

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 '/\/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 
Signed-off-by: Linus Torvalds

Merge branches 'acpi-pm', 'acpi-video', 'acpi-apei' and 'acpi-extlog'

2024-01-04T12:19:40+00:00

Merge an ACPI power management change, ACPI backlight driver changes, APEI
updates and ACPI extlog driver changes for 6.8-rc1:

 - Modify the ACPI LPIT table handling code to avoid u32 multiplication
   overflows in state residency computations (Nikita Kiryushin).

 - Drop an unused helper function from the ACPI backlight (video) driver
   and add a clarifying comment to it (Hans de Goede).

 - Update the ACPI backlight driver to avoid using uninitialized memory
   in some cases (Nikita Kiryushin).

 - Add ACPI backlight quirk for the Colorful X15 AT 23 laptop (Yuluo
   Qiu).

 - Add support for vendor-defined error types to the ACPI APEI error
   injection code (Avadhut Naik).

 - Adjust APEI to properly set MF_ACTION_REQUIRED on synchronous memory
   failure events, so they are handled differently from the asynchronous
   ones (Shuai Xue).

 - Fix NULL pointer dereference check in the ACPI extlog driver (Prarit
   Bhargava).

 - Adjust the ACPI extlog driver to clear the Extended Error Log status
   when RAS_CEC handled the error (Tony Luck).

* acpi-pm:
  ACPI: LPIT: Avoid u32 multiplication overflow

* acpi-video:
  ACPI: video: Add quirk for the Colorful X15 AT 23 Laptop
  ACPI: video: check for error while searching for backlight device parent
  ACPI: video: Drop should_check_lcd_flag()
  ACPI: video: Add comment about acpi_video_backlight_use_native() usage

* acpi-apei:
  ACPI: APEI: set memory failure flags as MF_ACTION_REQUIRED on synchronous events
  ACPI: APEI: EINJ: Add support for vendor defined error types
  platform/chrome: cros_ec_debugfs: Fix permissions for panicinfo
  fs: debugfs: Add write functionality to debugfs blobs
  ACPI: APEI: EINJ: Refactor available_error_type_show()

* acpi-extlog:
  ACPI: extlog: Clear Extended Error Log status when RAS_CEC handled the error
  ACPI: extlog: fix NULL pointer dereference check

debugfs: initialize cancellations earlier

2023-12-22T06:33:02+00:00

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 
Signed-off-by: Johannes Berg 
Link: https://lore.kernel.org/r/20231221150444.1e47a0377f80.If7e8ba721ba2956f12c6e8405e7d61e154aa7ae7@changeid
Signed-off-by: Greg Kroah-Hartman

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

2023-12-04T06:43:16+00:00

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 
Link: https://lore.kernel.org/r/20231202114936.fd55431ab160.I911aa53abeeca138126f690d383a89b13eb05667@changeid
Signed-off-by: Greg Kroah-Hartman

Merge tag 'wireless-2023-11-29' of git://git.kernel.org/pub/scm/linux/kernel/git/wireless/wireless

2023-11-30T03:43:34+00:00

Johannes Berg says:

====================
wireless fixes:
 - debugfs had a deadlock (removal vs. use of files),
   fixes going through wireless ACKed by Greg
 - support for HT STAs on 320 MHz channels, even if it's
   not clear that should ever happen (that's 6 GHz), best
   not to WARN()
 - fix for the previous CQM fix that broke most cases
 - various wiphy locking fixes
 - various small driver fixes

* tag 'wireless-2023-11-29' of git://git.kernel.org/pub/scm/linux/kernel/git/wireless/wireless:
  wifi: mac80211: use wiphy locked debugfs for sdata/link
  wifi: mac80211: use wiphy locked debugfs helpers for agg_status
  wifi: cfg80211: add locked debugfs wrappers
  debugfs: add API to allow debugfs operations cancellation
  debugfs: annotate debugfs handlers vs. removal with lockdep
  debugfs: fix automount d_fsdata usage
  wifi: mac80211: handle 320 MHz in ieee80211_ht_cap_ie_to_sta_ht_cap
  wifi: avoid offset calculation on NULL pointer
  wifi: cfg80211: hold wiphy mutex for send_interface
  wifi: cfg80211: lock wiphy mutex for rfkill poll
  wifi: cfg80211: fix CQM for non-range use
  wifi: mac80211: do not pass AP_VLAN vif pointer to drivers during flush
  wifi: iwlwifi: mvm: fix an error code in iwl_mvm_mld_add_sta()
  wifi: mt76: mt7925: fix typo in mt7925_init_he_caps
  wifi: mt76: mt7921: fix 6GHz disabled by the missing default CLC config
====================

Link: https://lore.kernel.org/r/20231129150809.31083-3-johannes@sipsolutions.net
Signed-off-by: Jakub Kicinski

debugfs: add API to allow debugfs operations cancellation

2023-11-27T10:24:55+00:00

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 
Signed-off-by: Johannes Berg

debugfs: annotate debugfs handlers vs. removal with lockdep

2023-11-27T10:24:50+00:00

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 
Signed-off-by: Johannes Berg