pussuw commented on code in PR #16486:
URL: https://github.com/apache/nuttx/pull/16486#discussion_r2128565957
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include/nuttx/spinlock.h:
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@@ -499,6 +543,85 @@ irqstate_t spin_lock_irqsave(FAR volatile spinlock_t *lock)
# define spin_lock_irqsave(l) ((void)(l), up_irq_save())
#endif
+/****************************************************************************
+ * Name: spin_lock_irqsave_nopreempt
+ *
+ * Description:
+ * If SMP is enabled:
+ * Disable local interrupts, sched_lock and take the lock spinlock and
+ * return the interrupt state.
+ *
+ * NOTE: This API is very simple to protect data (e.g. H/W register
+ * or internal data structure) in SMP mode. But do not use this API
+ * with kernel APIs which suspend a caller thread. (e.g. nxsem_wait)
+ *
+ * If SMP is not enabled:
+ * This function is equivalent to up_irq_save() + sched_lock().
+ *
+ * Input Parameters:
+ * lock - Caller specific spinlock. not NULL.
+ *
+ * Returned Value:
+ * An opaque, architecture-specific value that represents the state of
+ * the interrupts prior to the call to spin_lock_irqsave(lock);
+ *
+ ****************************************************************************/
+
+static inline_function
+irqstate_t spin_lock_irqsave_nopreempt(FAR volatile spinlock_t *lock)
+{
+ irqstate_t flags;
+ flags = spin_lock_irqsave(lock);
+ sched_lock();
+ return flags;
+}
+
+/****************************************************************************
+ * Name: rspin_lock_irqsave_noprempt
+ *
+ * Description:
+ * Nest supported spinlock, can support UINT8_MAX max depth.
+ * As we should not disable irq for long time, sched also locked.
+ * Similar feature with enter_critical_section, but isolate by instance.
+ *
+ * If SPINLOCK is enabled:
+ * Will take spinlock each cpu first call.
+ *
+ * If SPINLOCK is not enabled:
+ * Equivalent to up_irq_save() + sched_lock().
+ * Will only sched_lock once when first called.
+ *
+ * Input Parameters:
+ * lock - Caller specific rspinlock_s. not NULL.
+ *
+ * Returned Value:
+ * An opaque, architecture-specific value that represents the state of
+ * the interrupts prior to the call to spin_lock_irqsave(lock);
+ *
+ ****************************************************************************/
+
+static inline_function
+irqstate_t rspin_lock_irqsave_noprempt(FAR struct rspinlock_s *lock)
+{
+ /* For race condition, we may get cpuid in stack and then thread
+ * moved to other cpu. So we have to get cpuid with irq disabled.
+ */
+
+ irqstate_t flags = up_irq_save();
+ int cpu = this_cpu();
+
+ if (lock->holder != cpu)
+ {
+ spin_lock(&lock->lock);
Review Comment:
Do all platforms implement SMP barrier in spin_lock ? If not, you need to
add SMP barrier or use atomic_xxx to access / modify lock->holder and
lock->count.
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