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Linus Torvalds b8d5109f50 lockref: remove unused 'lockref_get_or_lock()' function 
Looking at the conditional lock acquire functions in the kernel due to
the new sparse support (see commit 4a557a5d1a "sparse: introduce
conditional lock acquire function attribute"), it became obvious that
the lockref code has a couple of them, but they don't match the usual
naming convention for the other ones, and their return value logic is
also reversed.

In the other very similar places, the naming pattern is '*_and_lock()'
(eg 'atomic_put_and_lock()' and 'refcount_dec_and_lock()'), and the
function returns true when the lock is taken.

The lockref code is superficially very similar to the refcount code,
only with the special "atomic wrt the embedded lock" semantics.  But
instead of the '*_and_lock()' naming it uses '*_or_lock()'.

And instead of returning true in case it took the lock, it returns true
if it *didn't* take the lock.

Now, arguably the reflock code is quite logical: it really is a "either
decrement _or_ lock" kind of situation - and the return value is about
whether the operation succeeded without any special care needed.

So despite the similarities, the differences do make some sense, and
maybe it's not worth trying to unify the different conditional locking
primitives in this area.

But while looking at this all, it did become obvious that the
'lockref_get_or_lock()' function hasn't actually had any users for
almost a decade.

The only user it ever had was the shortlived 'd_rcu_to_refcount()'
function, and it got removed and replaced with 'lockref_get_not_dead()'
back in 2013 in commits 0d98439ea3 ("vfs: use lockred 'dead' flag to
mark unrecoverably dead dentries") and e5c832d555 ("vfs: fix dentry
RCU to refcounting possibly sleeping dput()")

In fact, that single use was removed less than a week after the whole
function was introduced in commit b3abd80250 ("lockref: add
'lockref_get_or_lock() helper") so this function has been around for a
decade, but only had a user for six days.

Let's just put this mis-designed and unused function out of its misery.

We can think about the naming and semantic oddities of the remaining
'lockref_put_or_lock()' later, but at least that function has users.

And while the naming is different and the return value doesn't match,
that function matches the whole '{atomic,refcount}_dec_and_test()'
pattern much better (ie the magic happens when the count goes down to
zero, not when it is incremented from zero).

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-07-03 14:40:28 -07:00
arch parisc architecture fixes for kernel v5.19-rc5: 2022-07-02 10:23:36 -07:00
block block: remove WARN_ON() from bd_link_disk_holder 2022-06-23 07:48:05 -06:00
certs Certs changes 2022-06-21 12:13:53 -05:00
crypto Certs changes 2022-06-21 12:13:53 -05:00
Documentation A NULL pointer dereference fix for vc4, and 3 patches to improve the 2022-07-01 09:27:55 +10:00
drivers libnvdimm fixes for v5.19-rc5 2022-07-01 16:58:19 -07:00
fs Fixes for 5.19-rc5: 2022-07-03 09:42:17 -07:00
include lockref: remove unused 'lockref_get_or_lock()' function 2022-07-03 14:40:28 -07:00
init gcc-12: disable '-Warray-bounds' universally for now 2022-06-09 10:11:12 -07:00
ipc These changes update the ipc sysctls so that they are fundamentally 2022-06-03 15:54:57 -07:00
kernel tick/nohz: unexport __init-annotated tick_nohz_full_setup() 2022-06-27 10:43:12 -07:00
lib lockref: remove unused 'lockref_get_or_lock()' function 2022-07-03 14:40:28 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm Minor things, mainly - mailmap updates, MAINTAINERS updates, etc. 2022-06-26 14:00:55 -07:00
net Notable regression fixes: 2022-07-02 11:20:56 -07:00
samples fprobe, samples: Add use_trace option and show hit/missed counter 2022-06-17 21:53:29 +02:00
scripts kbuild: Ignore __this_module in gen_autoksyms.sh 2022-06-26 06:15:05 +09:00
security selinux: free contexts previously transferred in selinux_add_opt() 2022-06-15 21:20:45 -04:00
sound sound fixes for 5.19-rc4 2022-06-23 08:44:00 -05:00
tools perf tools fixes for v5.19: 3rd batch 2022-07-02 09:28:36 -07:00
usr Not a lot of material this cycle. Many singleton patches against various 2022-05-27 11:22:03 -07:00
virt KVM: x86: disable preemption around the call to kvm_arch_vcpu_{un|}blocking 2022-06-09 10:52:20 -04:00
.clang-format clang-format: Fix space after for_each macros 2022-05-20 19:27:16 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: split the second line of *.mod into *.usyms 2022-05-08 03:16:59 +09:00
.mailmap mailmap: add entry for Christian Marangi 2022-06-16 19:11:32 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: replace a Microchip AT91 maintainer 2022-02-09 11:30:01 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Two small fixes 2022-07-01 10:01:32 -07:00
Makefile Linux 5.19-rc4 2022-06-26 14:22:10 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.