linux-kernel - [PATCH 0/2] local_lock: Move this_cpu_ptr() notation from internal to main header

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Message-ID: <20250514110750.852919-1-bigeasy@linutronix.de>
Date: Wed, 14 May 2025 13:07:48 +0200
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: linux-kernel@...r.kernel.org,
	linux-rt-devel@...ts.linux.dev
Cc: tglx@...utronix.de,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Will Deacon <will@...nel.org>,
	Waiman Long <longman@...hat.com>,
	Boqun Feng <boqun.feng@...il.com>,
	Alexei Starovoitov <alexei.starovoitov@...il.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH 0/2] local_lock: Move this_cpu_ptr() notation from internal to main header

While looking at what needs extra locks for PREEMPT_RT in order to rid
of the lock in local_bh_disable() I stumbled uppon two users which need
to lock the structure but the pointer is no longer per_cpu.

Patch #1 moves this_cpu_ptr() from the internal header to the main on in
         order to free the name space and have the __ prefix function to
	 do the same but without the this_cpu_ptr(). So
	   local_lock_nested_bh()   -> on per-CPU memory
	   __local_lock_nested_bh() -> on local memory.

         This change has been made to all local_lock*() functions.

Patch #2 is an example why it is needed. In a nutshell the per-CPU
         memory is allocated via alloc_percpu() and then the memory is
	 passed to queue_work_on(). The worker then retrieves the
	 structure via container_of(). No more per-CPU memory.

I attached #2 as an example and would route via crypto once #1 is
accepted. The user user I identified is nf_set_pipapo which is doing
something similar. This makes two users in total.

Sebastian Andrzej Siewior (2):
  local_lock: Move this_cpu_ptr() notation from internal to main header.
  cryptd: Use nested-BH locking for cryptd_cpu_queue

 crypto/cryptd.c                     |  6 ++++++
 include/linux/local_lock.h          | 20 +++++++++----------
 include/linux/local_lock_internal.h | 30 ++++++++++++++---------------
 3 files changed, 31 insertions(+), 25 deletions(-)

-- 
2.49.0