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serial: qcom-geni: do not kill the machine on fifo underrun

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The Qualcomm GENI serial driver did not handle buffer flushing and used
to print discarded characters when the circular buffer was cleared.
Since commit 1788cf6a91d9 ("tty: serial: switch from circ_buf to kfifo")
this instead resulted in a hard lockup due to
qcom_geni_serial_send_chunk_fifo() spinning indefinitely in the
interrupt handler.

The underlying bugs have now been fixed, but make sure to output NUL
characters instead of killing the machine if a similar driver bug is
ever reintroduced.

Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20240704101805.30612-4-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Johan Hovold 2024-07-04 12:18:05 +02:00 committed by Greg Kroah-Hartman
parent 507786c51c
commit 2ac33975ab
1 changed files with 1 additions and 1 deletions
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2
drivers/tty/serial/qcom_geni_serial.c
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@ -878,7 +878,7 @@ static void qcom_geni_serial_send_chunk_fifo(struct uart_port *uport,
memset(buf, 0, sizeof(buf));
tx_bytes = min(remaining, BYTES_PER_FIFO_WORD);
tx_bytes = uart_fifo_out(uport, buf, tx_bytes);
uart_fifo_out(uport, buf, tx_bytes);
iowrite32_rep(uport->membase + SE_GENI_TX_FIFOn, buf, 1);