From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: linux-kernel@vger.kernel.org
Cc: tglx@linutronix.de, Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Anna-Maria Gleixner <anna-maria@linutronix.de>,
Richard Henderson <rth@twiddle.net>,
Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
Matt Turner <mattst88@gmail.com>,
linux-alpha@vger.kernel.org
Subject: [PATCH 1.5/5] alpha: atomic: provide asm for the fastpath for _atomic_dec_and_lock_irqsave
Date: Mon, 4 Jun 2018 12:27:57 +0200 [thread overview]
Message-ID: <20180604102757.h46feymcfdydl4nz@linutronix.de> (raw)
In-Reply-To: <20180604102559.2ynbassthjzva62l@linutronix.de>
I just looked at Alpha's atomic_dec_and_lock assembly and did something
that should work for atomic_dec_and_lock_irqsave. I think it works but I
would prefer for someone from the Alpha-Camp to ack this before it goes
in. It is not critical because the non-optimized version should work.
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: linux-alpha@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
arch/alpha/lib/dec_and_lock.c | 33 ++++++++++++++++++++++++++-------
1 file changed, 26 insertions(+), 7 deletions(-)
diff --git a/arch/alpha/lib/dec_and_lock.c b/arch/alpha/lib/dec_and_lock.c
index 069fef7372dc..d29ba1de4f68 100644
--- a/arch/alpha/lib/dec_and_lock.c
+++ b/arch/alpha/lib/dec_and_lock.c
@@ -32,6 +32,28 @@ _atomic_dec_and_lock: \n\
.previous \n\
.end _atomic_dec_and_lock");
+ asm (".text \n\
+ .global _atomic_dec_and_lock_irqsave \n\
+ .ent _atomic_dec_and_lock_irqsave \n\
+ .align 4 \n\
+_atomic_dec_and_lock_irqsave: \n\
+ .prologue 0 \n\
+1: ldl_l $1, 0($16) \n\
+ subl $1, 1, $1 \n\
+ beq $1, 2f \n\
+ stl_c $1, 0($16) \n\
+ beq $1, 4f \n\
+ mb \n\
+ clr $0 \n\
+ ret \n\
+2: br $29, 3f \n\
+3: ldgp $29, 0($29) \n\
+ br $atomic_dec_and_lock_irqsave1..ng \n\
+ .subsection 2 \n\
+4: br 1b \n\
+ .previous \n\
+ .end _atomic_dec_and_lock_irqsave");
+
static int __used atomic_dec_and_lock_1(atomic_t *atomic, spinlock_t *lock)
{
/* Slow path */
@@ -43,14 +65,11 @@ static int __used atomic_dec_and_lock_1(atomic_t *atomic, spinlock_t *lock)
}
EXPORT_SYMBOL(_atomic_dec_and_lock);
-int _atomic_dec_and_lock_irqsave(atomic_t *atomic, spinlock_t *lock,
- unsigned long *flags)
+static int __used atomic_dec_and_lock_irqsave1(atomic_t *atomic,
+ spinlock_t *lock,
+ unsigned long *flags)
{
- /* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */
- if (atomic_add_unless(atomic, -1, 1))
- return 0;
-
- /* Otherwise do it the slow way */
+ /* Slow way */
spin_lock_irqsave(lock, *flags);
if (atomic_dec_and_test(atomic))
return 1;
--
2.17.1
next prev parent reply other threads:[~2018-06-04 10:28 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-04 15:45 Introduce atomic_dec_and_lock_irqsave() Sebastian Andrzej Siewior
2018-05-04 15:45 ` [PATCH 1/5] spinlock: atomic_dec_and_lock: Add an irqsave variant Sebastian Andrzej Siewior
2018-06-04 10:25 ` [PATCH 1/5 v2] " Sebastian Andrzej Siewior
2018-06-04 10:27 ` Sebastian Andrzej Siewior [this message]
2018-06-04 11:48 ` [PATCH 1.5/5] alpha: atomic: provide asm for the fastpath for _atomic_dec_and_lock_irqsave Peter Zijlstra
2018-06-04 12:55 ` Sebastian Andrzej Siewior
2018-06-06 11:18 ` [PATCH 0.5/5] alpha: remove custom dec_and_lock() implementation Sebastian Andrzej Siewior
2018-06-06 11:21 ` Sebastian Andrzej Siewior
2018-06-06 11:59 ` Peter Zijlstra
2018-06-12 21:36 ` [tip:locking/urgent] alpha: Remove " tip-bot for Sebastian Andrzej Siewior
2018-05-04 15:45 ` [PATCH 2/5] mm/backing-dev: Use irqsave variant of atomic_dec_and_lock() Sebastian Andrzej Siewior
2018-05-04 15:45 ` [PATCH 3/5] kernel/user: " Sebastian Andrzej Siewior
2018-05-04 15:45 ` [PATCH 4/5] drivers/md/raid5: " Sebastian Andrzej Siewior
2018-05-04 15:45 ` [PATCH 5/5] drivers/md/raid5: Do not disable irq on release_inactive_stripe_list() call Sebastian Andrzej Siewior
2018-05-04 15:54 ` Introduce atomic_dec_and_lock_irqsave() Peter Zijlstra
2018-05-04 16:07 ` Sebastian Andrzej Siewior
2018-05-04 16:21 ` Peter Zijlstra
2018-05-04 16:26 ` Al Viro
2018-05-04 16:38 ` Peter Zijlstra
2018-05-23 13:02 ` Peter Zijlstra
2018-05-30 9:26 ` Sebastian Andrzej Siewior
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