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From: Helge Deller <deller@gmx.de>
To: linux-parisc@vger.kernel.org,
	James Bottomley <James.Bottomley@hansenpartnership.com>,
	John David Anglin <dave.anglin@bell.net>
Subject: [PATCH] parisc: Improve interrupt handling in arch_spin_lock_flags()
Date: Sun, 5 Apr 2020 22:37:43 +0200	[thread overview]
Message-ID: <20200405203743.GA24551@ls3530.fritz.box> (raw)

Rewrite arch_spin_lock() and arch_spin_lock_flags() to not re-enable and
disable the PSW_SM_I interrupt flag too often.

Signed-off-by: Helge Deller <deller@gmx.de>

diff --git a/arch/parisc/include/asm/spinlock.h b/arch/parisc/include/asm/spinlock.h
index 197d2247e4db..51582eacb7ec 100644
--- a/arch/parisc/include/asm/spinlock.h
+++ b/arch/parisc/include/asm/spinlock.h
@@ -10,25 +10,34 @@
 static inline int arch_spin_is_locked(arch_spinlock_t *x)
 {
 	volatile unsigned int *a = __ldcw_align(x);
+	smp_mb();
 	return *a == 0;
 }

-#define arch_spin_lock(lock) arch_spin_lock_flags(lock, 0)
+static inline void arch_spin_lock(arch_spinlock_t *x)
+{
+	volatile unsigned int *a;
+
+	a = __ldcw_align(x);
+	while (__ldcw(a) == 0)
+		while (*a == 0)
+			cpu_relax();
+}

 static inline void arch_spin_lock_flags(arch_spinlock_t *x,
 					 unsigned long flags)
 {
 	volatile unsigned int *a;
+	unsigned long flags_dis;

 	a = __ldcw_align(x);
-	while (__ldcw(a) == 0)
+	while (__ldcw(a) == 0) {
+		local_save_flags(flags_dis);
+		local_irq_restore(flags);
 		while (*a == 0)
-			if (flags & PSW_SM_I) {
-				local_irq_enable();
-				cpu_relax();
-				local_irq_disable();
-			} else
-				cpu_relax();
+			cpu_relax();
+		local_irq_restore(flags_dis);
+	}
 }
 #define arch_spin_lock_flags arch_spin_lock_flags


                 reply	other threads:[~2020-04-05 20:37 UTC|newest]

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