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drivers/serial/serial.c: In DMA mode, the use of uart_disablexinit() is insufficient to protect a critical section. enter/leave_critical_section() must be used in those cases if CONFIG_SERIAL_DMA=y

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This commit is contained in:
Xiang Xiao 2018-08-26 10:30:48 -06:00 committed by Gregory Nutt
parent 9e922873d4
commit ea62b13fd0
1 changed files with 28 additions and 10 deletions
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38
drivers/serial/serial.c
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@ -887,33 +887,45 @@ static ssize_t uart_read(FAR struct file *filep, FAR char *buffer, size_t buflen
else
{
#ifdef CONFIG_SERIAL_DMA
/* Disable all interrupts and test again...
* uart_disablerxint() is insufficient for the check in DMA mode.
*/
flags = enter_critical_section();
#else
/* Disable Rx interrupts and test again... */
uart_disablerxint(dev);
#endif
/* If the Rx ring buffer still empty? Bytes may have been addded
* between the last time that we checked and when we disabled Rx
/* If the Rx ring buffer still empty? Bytes may have been added
* between the last time that we checked and when we disabled
* interrupts.
*/
if (rxbuf->head == rxbuf->tail)
{
/* Yes.. the buffer is still empty. Wait for some characters
* to be received into the buffer with the RX interrupt re-
* enabled. All interrupts are disabled briefly to assure
* that the following operations are atomic.
/* Yes.. the buffer is still empty. We will need to wait for
* additional data to be received.
*/
flags = enter_critical_section();
#ifdef CONFIG_SERIAL_DMA
/* Notify DMA that there is free space in the RX buffer */
uart_dmarxfree(dev);
#endif
#else
/* Wait with the RX interrupt re-enabled. All interrupts are
* disabled briefly to assure that the following operations
* are atomic.
*/
flags = enter_critical_section();
/* Re-enable UART Rx interrupts */
uart_enablerxint(dev);
#endif
#ifdef CONFIG_SERIAL_REMOVABLE
/* Check again if the removable device is still connected
@ -928,7 +940,7 @@ static ssize_t uart_read(FAR struct file *filep, FAR char *buffer, size_t buflen
else
#endif
{
/* Now wait with the Rx interrupt re-enabled. NuttX will
/* Now wait with the Rx interrupt enabled. NuttX will
* automatically re-enable global interrupts when this
* thread goes to sleep.
*/
@ -979,7 +991,11 @@ static ssize_t uart_read(FAR struct file *filep, FAR char *buffer, size_t buflen
* the loop.
*/
#ifdef CONFIG_SERIAL_DMA
leave_critical_section(flags);
#else
uart_enablerxint(dev);
#endif
}
}
}
@ -992,9 +1008,11 @@ static ssize_t uart_read(FAR struct file *filep, FAR char *buffer, size_t buflen
leave_critical_section(flags);
#endif
#ifndef CONFIG_SERIAL_DMA
/* RX interrupt could be disabled by RX buffer overflow. Enable it now. */
uart_enablerxint(dev);
#endif
#ifdef CONFIG_SERIAL_IFLOWCONTROL
#ifdef CONFIG_SERIAL_IFLOWCONTROL_WATERMARKS