linux-kernel - [PATCH 5.7 369/393] Revert "parisc: Improve interrupt handling in arch_spin_lock

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Date:   Mon, 17 Aug 2020 17:16:59 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Helge Deller <deller@....de>
Subject: [PATCH 5.7 369/393] Revert "parisc: Improve interrupt handling in arch_spin_lock_flags()"

From: Helge Deller <deller@....de>

commit 3d05b8aebc5f10ee3ab129b61100196855dd7249 upstream.

This reverts commit 2772f0efd5bbd5413db3d22e363b779ca0fa5310.
It turns out that we want to implement the spinlock code differently.

Signed-off-by: Helge Deller <deller@....de>
Cc: <stable@...r.kernel.org> # v5.7+
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/parisc/include/asm/spinlock.h |   25 ++++++++-----------------
 1 file changed, 8 insertions(+), 17 deletions(-)

--- a/arch/parisc/include/asm/spinlock.h
+++ b/arch/parisc/include/asm/spinlock.h
@@ -10,34 +10,25 @@
 static inline int arch_spin_is_locked(arch_spinlock_t *x)
 {
 	volatile unsigned int *a = __ldcw_align(x);
-	smp_mb();
 	return *a == 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();
-}
+#define arch_spin_lock(lock) arch_spin_lock_flags(lock, 0)
 
 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) {
-		local_save_flags(flags_dis);
-		local_irq_restore(flags);
+	while (__ldcw(a) == 0)
 		while (*a == 0)
-			cpu_relax();
-		local_irq_restore(flags_dis);
-	}
+			if (flags & PSW_SM_I) {
+				local_irq_enable();
+				cpu_relax();
+				local_irq_disable();
+			} else
+				cpu_relax();
 }
 #define arch_spin_lock_flags arch_spin_lock_flags