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firmware: protect uart_tx_queue against ISR

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cardem:
- dispatch_usb_command_cardem() appends to uart_tx_queue from the main loop
- tx_byte_tpdu() dequeues from the USART IRQ handler @ NVIC prio 0

card_handle_reset() has the same issue, drains queue and
frees uart_tx_msg from main loop while the ISR may own them.

All of this needs protection against the irq.

Needs a fixed llist_add_tail_irqsafe(), which called __enable_irq() instead of
restoring the saved PRIMASK for some unknown reason?!?!?!?

Change-Id: I7d9cdcc56263b27dfd4649dfb1da1d67761ee923
This commit is contained in:
Eric Wild
2026-07-28 17:42:32 +02:00
committed by lynxis lazus
parent b36adff672
commit f7170aff42
3 changed files with 21 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files
firmware/libcommon/source/card_emu.c
+18 -6
View File
@@ -219,19 +219,31 @@ struct card_handle {
static void card_handle_reset(struct card_handle *ch)
{
struct msgb *msg;
unsigned long x;
card_emu_uart_update_wt(ch->uart_chan, 0);
/* release any buffers we may still own */
if (ch->uart_tx_msg) {
usb_buf_free(ch->uart_tx_msg);
ch->uart_tx_msg = NULL;
}
/* Release any buffers we may still own.
* uart_tx_msg + uart_tx_queue are shared with the UART IRQ handler,
* that preempts us here -> needs atomic detach and free */
local_irq_save(x);
msg = ch->uart_tx_msg;
ch->uart_tx_msg = NULL;
local_irq_restore(x);
if (msg)
usb_buf_free(msg);
if (ch->uart_rx_msg) {
usb_buf_free(ch->uart_rx_msg);
ch->uart_rx_msg = NULL;
}
while ((msg = msgb_dequeue(&ch->uart_tx_queue))) {
while (1) {
local_irq_save(x);
msg = msgb_dequeue(&ch->uart_tx_queue);
local_irq_restore(x);
if (!msg)
break;
usb_buf_free(msg);
}
}
firmware/libcommon/source/mode_cardemu.c
+2 -1
View File
@@ -737,7 +737,8 @@ static void dispatch_usb_command_cardem(struct msgb *msg, struct cardem_inst *ci
switch (hdr->msg_type) {
case SIMTRACE_MSGT_DT_CEMU_TX_DATA:
queue = card_emu_get_uart_tx_queue(ci->ch);
llist_add_tail(&msg->list, queue);
/* drained from the USART IRQ handler at highest NVIC prio */
llist_add_tail_irqsafe(&msg->list, queue);
card_emu_have_new_uart_tx(ci->ch);
break;
case SIMTRACE_MSGT_DT_CEMU_SET_ATR: