Pull locking updates from Ingo Molnar:

 - Jump label fixes, including a perf events fix that originally
   manifested as jump label failures, but was a serialization bug at the
   usage site

 - Mark down_write*() helpers as __always_inline, to improve WCHAN
   debuggability

 - Misc cleanups and fixes

* tag 'locking-core-2024-07-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/rwsem: Add __always_inline annotation to __down_write_common() and inlined callers
  jump_label: Simplify and clarify static_key_fast_inc_cpus_locked()
  jump_label: Clarify condition in static_key_fast_inc_not_disabled()
  jump_label: Fix concurrency issues in static_key_slow_dec()
  perf/x86: Serialize set_attr_rdpmc()
  cleanup: Standardize the header guard define's name

Add a helper that returns the file descriptor and ensures that the old
variable contains a negative value. This makes it easy to rely on
CLASS(get_unused_fd).

Link: https://lore.kernel.org/r/20240627-work-pidfs-v1-1-7e9ab6cc3bb1@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

At some point during early development, the <linux/cleanup.h> header
must have been named <linux/guard.h>, as evidenced by the header
guard name:

  #ifndef __LINUX_GUARDS_H
  #define __LINUX_GUARDS_H

It ended up being <linux/cleanup.h>, but the old guard name for
a file name that was never upstream never changed.

Do that now - and while at it, also use the canonical _LINUX prefix,
instead of the less common __LINUX prefix.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/171664113181.10875.8784434350512348496.tip-bot2@tip-bot2

Adds:

 - DEFINE_GUARD_COND() / DEFINE_LOCK_GUARD_1_COND() to extend existing
   guards with conditional lock primitives, eg. mutex_trylock(),
   mutex_lock_interruptible().

   nb. both primitives allow NULL 'locks', which cause the lock to
       fail (obviously).

 - extends scoped_guard() to not take the body when the the
   conditional guard 'fails'. eg.

     scoped_guard (mutex_intr, &task->signal_cred_guard_mutex) {
	...
     }

   will only execute the body when the mutex is held.

 - provides scoped_cond_guard(name, fail, args...); which extends
   scoped_guard() to do fail when the lock-acquire fails.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20231102110706.460851167%40infradead.org

recent discussion brought about the realization that it makes sense for
no_free_ptr() to have __must_check semantics in order to avoid leaking
the resource.

Additionally, add a few comments to clarify why/how things work.

All credit to Linus on how to combine __must_check and the
stmt-expression.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20230816103102.GF980931@hirez.programming.kicks-ass.net

Use __attribute__((__cleanup__(func))) to build:

 - simple auto-release pointers using __free()

 - 'classes' with constructor and destructor semantics for
   scope-based resource management.

 - lock guards based on the above classes.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230612093537.614161713%40infradead.org