linux-kernel - Re: [PATCH locking/atomic 18/19] locking/atomic: Refrain from generating duplicate fallback kernel-doc

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Message-ID: <fc518edb-410b-4ea3-b628-26ef7d61000d@paulmck-laptop>
Date:   Thu, 11 May 2023 13:29:04 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org, akiyks@...il.com,
        linux-doc@...r.kernel.org, kernel-team@...a.com,
        Will Deacon <will@...nel.org>,
        Boqun Feng <boqun.feng@...il.com>,
        Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH locking/atomic 18/19] locking/atomic: Refrain from
 generating duplicate fallback kernel-doc

On Thu, May 11, 2023 at 10:18:37PM +0200, Peter Zijlstra wrote:
> On Wed, May 10, 2023 at 11:17:16AM -0700, Paul E. McKenney wrote:
> > The gen-atomics.sh script currently generates 42 duplicate definitions:
> > 
> > 	arch_atomic64_add_negative
> > 	arch_atomic64_add_negative_acquire
> > 	arch_atomic64_add_negative_release
> > 	arch_atomic64_dec_return
> > 	arch_atomic64_dec_return_acquire
> > 	arch_atomic64_dec_return_release
> > 	arch_atomic64_fetch_andnot
> > 	arch_atomic64_fetch_andnot_acquire
> > 	arch_atomic64_fetch_andnot_release
> > 	arch_atomic64_fetch_dec
> > 	arch_atomic64_fetch_dec_acquire
> > 	arch_atomic64_fetch_dec_release
> > 	arch_atomic64_fetch_inc
> > 	arch_atomic64_fetch_inc_acquire
> > 	arch_atomic64_fetch_inc_release
> > 	arch_atomic64_inc_return
> > 	arch_atomic64_inc_return_acquire
> > 	arch_atomic64_inc_return_release
> > 	arch_atomic64_try_cmpxchg
> > 	arch_atomic64_try_cmpxchg_acquire
> > 	arch_atomic64_try_cmpxchg_release
> > 	arch_atomic_add_negative
> > 	arch_atomic_add_negative_acquire
> > 	arch_atomic_add_negative_release
> > 	arch_atomic_dec_return
> > 	arch_atomic_dec_return_acquire
> > 	arch_atomic_dec_return_release
> > 	arch_atomic_fetch_andnot
> > 	arch_atomic_fetch_andnot_acquire
> > 	arch_atomic_fetch_andnot_release
> > 	arch_atomic_fetch_dec
> > 	arch_atomic_fetch_dec_acquire
> > 	arch_atomic_fetch_dec_release
> > 	arch_atomic_fetch_inc
> > 	arch_atomic_fetch_inc_acquire
> > 	arch_atomic_fetch_inc_release
> > 	arch_atomic_inc_return
> > 	arch_atomic_inc_return_acquire
> > 	arch_atomic_inc_return_release
> > 	arch_atomic_try_cmpxchg
> > 	arch_atomic_try_cmpxchg_acquire
> > 	arch_atomic_try_cmpxchg_release
> > 
> > These duplicates are presumably to handle different architectures
> > generating hand-coded definitions for different subsets of the atomic
> > operations.  However, generating duplicate kernel-doc headers is
> > undesirable.
> > 
> > Therefore, generate only the first kernel-doc definition in a group
> > of duplicates.  A comment indicates the name of the function and the
> > fallback script that generated it.
> 
> So my canonical solution to fixing kernel-doc related problems is this
> trivial regex:
> 
> 	s/\/\*\*/\/\*/
> 
> works every time.

Can't say that I am a fan of that approach.

> And is *much* simpler than this:
> 
> >  scripts/atomic/chkdup.sh                     |  27 ++
> >  scripts/atomic/fallbacks/acquire             |   3 +
> >  scripts/atomic/fallbacks/add_negative        |   5 +
> >  scripts/atomic/fallbacks/add_unless          |   5 +
> >  scripts/atomic/fallbacks/andnot              |   5 +
> >  scripts/atomic/fallbacks/dec                 |   5 +
> >  scripts/atomic/fallbacks/dec_and_test        |   5 +
> >  scripts/atomic/fallbacks/dec_if_positive     |   5 +
> >  scripts/atomic/fallbacks/dec_unless_positive |   5 +
> >  scripts/atomic/fallbacks/fence               |   3 +
> >  scripts/atomic/fallbacks/fetch_add_unless    |   5 +
> >  scripts/atomic/fallbacks/inc                 |   5 +
> >  scripts/atomic/fallbacks/inc_and_test        |   5 +
> >  scripts/atomic/fallbacks/inc_not_zero        |   5 +
> >  scripts/atomic/fallbacks/inc_unless_negative |   5 +
> >  scripts/atomic/fallbacks/read_acquire        |   5 +
> >  scripts/atomic/fallbacks/release             |   3 +
> >  scripts/atomic/fallbacks/set_release         |   5 +
> >  scripts/atomic/fallbacks/sub_and_test        |   5 +
> >  scripts/atomic/fallbacks/try_cmpxchg         |   5 +
> >  scripts/atomic/gen-atomics.sh                |   4 +

This is not a huge addition, now is it?

							Thanx, Paul