xiaoxiang781216 commented on code in PR #16466:
URL: https://github.com/apache/nuttx/pull/16466#discussion_r2124313387
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drivers/serial/serial.c:
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@@ -248,9 +249,26 @@ static int uart_putxmitchar(FAR uart_dev_t *dev, int ch,
bool oktoblock)
nexthead = 0;
}
- /* Check if the TX buffer is full */
+ /* Check if the TX buffer is full
+ *
+ * This method is currently called from uart_readv and uart_writev.
+ * The latter calls it after a call to uart_disabletxint, meaning
+ * transmit interrupt cannot happen. The former, however, runs
+ * with interrupt handling enabled. Interrupt handler can therefore
+ * execute in the middle of loading xmit.tail. If the load isn't
+ * atomic (8bit MCUs), it must run with interrupts disabled because
+ * the interrupt handler changes xmit.tail.
+ */
+
+#ifdef CONFIG_ARCH_LD_16BIT_NOT_ATOMIC
+ flags = enter_critical_section();
+ tail = dev->xmit.tail;
Review Comment:
let's use atomic_xxx api instead the critical section
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