xiaoxiang781216 commented on code in PR #10776:
URL: https://github.com/apache/nuttx/pull/10776#discussion_r1346359981
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sched/semaphore/spinlock.c:
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@@ -384,4 +388,138 @@ void spin_clrbit(FAR volatile cpu_set_t *set, unsigned
int cpu,
}
#endif
+#if defined(CONFIG_RW_SPINLOCK)
+
+/****************************************************************************
+ * Name: rw_read_spin_lock
+ *
+ * Description:
+ * If this CPU does not already hold the spinlock, then loop until the
+ * spinlock is successfully locked.
+ *
+ * This implementation is non-reentrant and set a bit of lock.
+ *
+ * The priority of reader is higher than writter if a reader hold the
+ * lock, a new reader can get its lock but writer can't get this lock.
+ *
+ * Input Parameters:
+ * lock - A reference to the spinlock object to lock.
+ *
+ * Returned Value:
+ * None. When the function returns, the spinlock was successfully locked
+ * by this CPU.
+ *
+ * Assumptions:
+ * Not running at the interrupt level.
+ *
+ ****************************************************************************/
+
+void rw_read_spin_lock(FAR volatile rw_spinlock_t *lock)
+{
+ while (atomic_load(lock) == -1)
+ {
+ SP_DSB();
+ SP_WFE();
+ }
+
+ atomic_fetch_add(lock, 1);
Review Comment:
race since another writer may hold lock after line 419 and before line 425
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