linux-kernel - Re: [PATCH 11/13] locking/qspinlock: Use queued_spin_trylock in pv_hybrid_queued_unfair

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Message-ID: <YsR1YxKr0ySn/2Wr@worktop.programming.kicks-ass.net>
Date:   Tue, 5 Jul 2022 19:31:15 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Nicholas Piggin <npiggin@...il.com>
Cc:     Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
        Waiman Long <longman@...hat.com>,
        Boqun Feng <boqun.feng@...il.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 11/13] locking/qspinlock: Use queued_spin_trylock in
 pv_hybrid_queued_unfair_trylock

On Tue, Jul 05, 2022 at 12:38:18AM +1000, Nicholas Piggin wrote:
> Rather than open-code it as necessitated by the old function-renaming
> code generation that rendered queued_spin_trylock unavailable to use
> here.
> 
> Signed-off-by: Nicholas Piggin <npiggin@...il.com>
> ---
>  kernel/locking/qspinlock.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
> index cef0ca7d94e1..9db168753124 100644
> --- a/kernel/locking/qspinlock.c
> +++ b/kernel/locking/qspinlock.c
> @@ -357,7 +357,7 @@ static inline bool pv_hybrid_queued_unfair_trylock(struct qspinlock *lock)
>  		int val = atomic_read(&lock->val);
>  
>  		if (!(val & _Q_LOCKED_PENDING_MASK) &&
> -		   (cmpxchg_acquire(&lock->locked, 0, _Q_LOCKED_VAL) == 0)) {
> +				queued_spin_trylock(lock)) {

Indenting went wild here; please use cino=(0:0 (if you're a vim user; I
seem to have misplaced the emacs equivalent).