linux-kernel - Re: [PATCH v3 0/8] cleanup: Introduce ACQUIRE(), a guard() for conditional locks

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Message-ID: <1e52ede4-6256-432c-b5a2-45c3342eca84@intel.com>
Date: Wed, 16 Jul 2025 13:52:04 -0700
From: Dave Jiang <dave.jiang@...el.com>
To: Dan Williams <dan.j.williams@...el.com>, linux-cxl@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
 Alison Schofield <alison.schofield@...el.com>,
 David Lechner <dlechner@...libre.com>, Davidlohr Bueso <dave@...olabs.net>,
 "Fabio M. De Francesco" <fabio.m.de.francesco@...ux.intel.com>,
 Ingo Molnar <mingo@...nel.org>, Ira Weiny <ira.weiny@...el.com>,
 Jonathan Cameron <jonathan.cameron@...wei.com>,
 Linus Torvalds <torvalds@...ux-foundation.org>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>,
 Shiju Jose <shiju.jose@...wei.com>, Vishal Verma <vishal.l.verma@...el.com>
Subject: Re: [PATCH v3 0/8] cleanup: Introduce ACQUIRE(), a guard() for
 conditional locks



On 7/11/25 4:49 PM, Dan Williams wrote:
> Changes since v2 [1]:
> - Pick up Acks and Reviews
> - Whitespace fixups for cleanup.h changes (Jonathan)
> - Use consistent local variable style for ACQUIRE_ERR() (Jonathan)
>   - Not addressed: switch to less compact style ACQUIRE_ERR()
> - Not addressed: pickup checkpatch change for ACQUIRE_ERR() style in
>   this series (Alison)
> - Drop the cxl_decoder_detach() CLASS() and convert to a helper function (Jonathan)
> - Refactor attach_target() to make it easier to read (Jonathan)

Applied to cxl/next
b873adfddeeb337fa8e9f381fd35eb94f7887f2f


> 
> [1]: http://lore.kernel.org/20250619050416.782871-1-dan.j.williams@intel.com
> 
> For those new to this set, the motivation for this work is that the CXL
> subsystem adopted scope-based-cleanup helpers and achieved some decent
> cleanups. However, that work stalled with conditional locks. It stalled
> due to the pain points of scoped_cond_guard(). See patch1.
> 
> In the interim, approaches like rwsem_read_intr_acquire() attempted to
> workaround the pain points, but started a "parallel universe" of helpers
> that is not sustainable.
> 
>     0c6e6f1357cb cxl/edac: Add CXL memory device patrol scrub control feature
> 
> Peter fixed all of this up in a manner consistent with existing guards.
> Take that proposal and run with it to unblock further cleanups of "goto"
> in unwind paths in the CXL subsystem.
> 
> Potential follow-on work identified by this effort:
> 
> - __GUARD_IS_ERR() asm helper [2]
> - Checkpatch fixups for proposed ACQUIRE_ERR() style [3]
> 
> [2]: http://lore.kernel.org/20250514064624.GA24938@noisy.programming.kicks-ass.net
> [3]: http://lore.kernel.org/aGXDMZB6omShJpoj@aschofie-mobl2.lan
> 
> Dan Williams (7):
>   cxl/mbox: Convert poison list mutex to ACQUIRE()
>   cxl/decoder: Move decoder register programming to a helper
>   cxl/decoder: Drop pointless locking
>   cxl/region: Split commit_store() into __commit() and queue_reset()
>     helpers
>   cxl/region: Move ready-to-probe state check to a helper
>   cxl/region: Consolidate cxl_decoder_kill_region() and
>     cxl_region_detach()
>   cxl: Convert to ACQUIRE() for conditional rwsem locking
> 
> Peter Zijlstra (1):
>   cleanup: Introduce ACQUIRE() and ACQUIRE_ERR() for conditional locks
> 
>  drivers/cxl/core/cdat.c   |   6 +-
>  drivers/cxl/core/core.h   |  32 ++-
>  drivers/cxl/core/edac.c   |  44 ++--
>  drivers/cxl/core/hdm.c    | 118 +++++-----
>  drivers/cxl/core/mbox.c   |  13 +-
>  drivers/cxl/core/memdev.c |  50 ++--
>  drivers/cxl/core/port.c   |  27 +--
>  drivers/cxl/core/region.c | 473 ++++++++++++++++++++------------------
>  drivers/cxl/cxl.h         |  13 +-
>  drivers/cxl/cxlmem.h      |   4 +-
>  include/linux/cleanup.h   |  95 ++++++--
>  include/linux/mutex.h     |   2 +-
>  include/linux/rwsem.h     |   3 +-
>  13 files changed, 480 insertions(+), 400 deletions(-)
> 
> 
> base-commit: e04c78d86a9699d136910cfc0bdcf01087e3267e