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xuartlite: fix race condition and receive overrun in XUartLite_SendBuffer #384

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xuartlite: fix race condition and receive overrun in XUartLite_SendBuffer #384

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28 changes: 15 additions & 13 deletions XilinxProcessorIPLib/drivers/uartlite/src/xuartlite.c
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Original file line number Diff line number Diff line change
Expand Up @@ -461,11 +461,6 @@ unsigned int XUartLite_SendBuffer(XUartLite *InstancePtr)
u8 StatusRegister;
u8 IntrEnableStatus;

/*
* Read the status register to determine if the transmitter is full
*/
StatusRegister = XUartLite_GetSR(InstancePtr);

/*
* Enter a critical region by disabling all the UART interrupts to allow
* this call to stop a previous operation that may be interrupt driven
Expand All @@ -481,20 +476,27 @@ unsigned int XUartLite_SendBuffer(XUartLite *InstancePtr)
*/
IntrEnableStatus = StatusRegister;

/*
* Read the status register to determine if the transmitter is full
*/
StatusRegister = XUartLite_GetSR(InstancePtr);

/*
* Fill the FIFO from the the buffer that was specified
*/
if(!(StatusRegister & XUL_SR_TX_FIFO_EMPTY)) {
SentCount = 0;
} else if(InstancePtr->SendBuffer.RemainingBytes > 15) {
SentCount = 15;
} else {
SentCount = InstancePtr->SendBuffer.RemainingBytes;
}

while (((StatusRegister & XUL_SR_TX_FIFO_FULL) == 0) &&
(SentCount < InstancePtr->SendBuffer.RemainingBytes)) {
for(int i = 0; i < SentCount; i += 1) {
XUartLite_WriteReg(InstancePtr->RegBaseAddress,
XUL_TX_FIFO_OFFSET,
InstancePtr->SendBuffer.NextBytePtr[
SentCount]);

SentCount++;

StatusRegister = XUartLite_GetSR(InstancePtr);
i]);
}

/*
Expand All @@ -506,7 +508,7 @@ unsigned int XUartLite_SendBuffer(XUartLite *InstancePtr)
/*
* Increment associated counters
*/
InstancePtr->Stats.CharactersTransmitted += SentCount;
InstancePtr->Stats.CharactersTransmitted += SentCount;

/*
* Restore the interrupt enable register to it's previous value such
Expand Down