HAL_ETH_Transmit_IT() and HAL_ETH_Transmit() do not set HAL_ETH_STATE_BUSY before modifying TX descriptors creating race-condition

[KarstenHohmeier]

HAL_ETH_Transmit_IT() and HAL_ETH_Transmit() both test gState but do not set it to HAL_ETH_STATE_BUSY before operating on the TX descriptors inside ETH_Prepare_Tx_Descriptors(). This creates a race-condition among themselves and among each other when used concurrently from multiple threads (e.g. preemption under FreeRTOS).

Also Test-and-Set of gState needs to be done atomically (see #70).

stm32h7xx_hal_driver/Src/stm32h7xx_hal_eth.c

Lines 1002 to 1009 in ceda3ce

	if (heth->gState == HAL_ETH_STATE_STARTED)
	{
	/* Save the packet pointer to release. */
	heth->TxDescList.CurrentPacketAddress = (uint32_t *)pTxConfig->pData;
	/* Config DMA Tx descriptor by Tx Packet info */
	if (ETH_Prepare_Tx_Descriptors(heth, pTxConfig, 1) != HAL_ETH_ERROR_NONE)
	{

Expected was at minimum a Test-and-Set like this:

stm32h7xx_hal_driver/Src/stm32h7xx_hal_eth.c

Lines 719 to 721 in ceda3ce

	if (heth->gState == HAL_ETH_STATE_READY)
	{
	heth->gState = HAL_ETH_STATE_BUSY;

[ASEHSTM]

ST Internal Reference: 191088