Thread (11 messages) 11 messages, 3 authors, 2019-08-01

Re: [PATCH 1/3] powerpc/spinlocks: Refactor SHARED_PROCESSOR

From: Andrew Donnellan <hidden>
Date: 2019-08-01 03:23:05

On 28/7/19 10:54 pm, Christopher M. Riedl wrote:
Determining if a processor is in shared processor mode is not a constant
so don't hide it behind a #define.

Signed-off-by: Christopher M. Riedl <redacted>
This seems aesthetically more right.

Reviewed-by: Andrew Donnellan <redacted>
quoted hunk ↗ jump to hunk
---
  arch/powerpc/include/asm/spinlock.h | 21 +++++++++++++++------
  1 file changed, 15 insertions(+), 6 deletions(-)
diff --git a/arch/powerpc/include/asm/spinlock.h b/arch/powerpc/include/asm/spinlock.h
index a47f827bc5f1..8631b0b4e109 100644
--- a/arch/powerpc/include/asm/spinlock.h
+++ b/arch/powerpc/include/asm/spinlock.h
@@ -101,15 +101,24 @@ static inline int arch_spin_trylock(arch_spinlock_t *lock)
  
  #if defined(CONFIG_PPC_SPLPAR)
  /* We only yield to the hypervisor if we are in shared processor mode */
-#define SHARED_PROCESSOR (lppaca_shared_proc(local_paca->lppaca_ptr))
  extern void __spin_yield(arch_spinlock_t *lock);
  extern void __rw_yield(arch_rwlock_t *lock);
  #else /* SPLPAR */
  #define __spin_yield(x)	barrier()
  #define __rw_yield(x)	barrier()
-#define SHARED_PROCESSOR	0
  #endif
  
+static inline bool is_shared_processor(void)
+{
+/* Only server processors have an lppaca struct */
+#ifdef CONFIG_PPC_BOOK3S
+	return (IS_ENABLED(CONFIG_PPC_SPLPAR) &&
+		lppaca_shared_proc(local_paca->lppaca_ptr));
+#else
+	return false;
+#endif
+}
+
  static inline void arch_spin_lock(arch_spinlock_t *lock)
  {
  	while (1) {
@@ -117,7 +126,7 @@ static inline void arch_spin_lock(arch_spinlock_t *lock)
  			break;
  		do {
  			HMT_low();
-			if (SHARED_PROCESSOR)
+			if (is_shared_processor())
  				__spin_yield(lock);
  		} while (unlikely(lock->slock != 0));
  		HMT_medium();
@@ -136,7 +145,7 @@ void arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags)
  		local_irq_restore(flags);
  		do {
  			HMT_low();
-			if (SHARED_PROCESSOR)
+			if (is_shared_processor())
  				__spin_yield(lock);
  		} while (unlikely(lock->slock != 0));
  		HMT_medium();
@@ -226,7 +235,7 @@ static inline void arch_read_lock(arch_rwlock_t *rw)
  			break;
  		do {
  			HMT_low();
-			if (SHARED_PROCESSOR)
+			if (is_shared_processor())
  				__rw_yield(rw);
  		} while (unlikely(rw->lock < 0));
  		HMT_medium();
@@ -240,7 +249,7 @@ static inline void arch_write_lock(arch_rwlock_t *rw)
  			break;
  		do {
  			HMT_low();
-			if (SHARED_PROCESSOR)
+			if (is_shared_processor())
  				__rw_yield(rw);
  		} while (unlikely(rw->lock != 0));
  		HMT_medium();
-- 
Andrew Donnellan              OzLabs, ADL Canberra
ajd@linux.ibm.com             IBM Australia Limited
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