| Message ID | 20241001125033.10625-3-johan+linaro@kernel.org |
|---|---|
| State | New |
| Headers | show |
| Series | serial: qcom-geni: fix receiver enable | expand |
Hi, On Tue, Oct 1, 2024 at 5:51 AM Johan Hovold <johan+linaro@kernel.org> wrote: > > A commit adding back the stopping of tx on port shutdown failed to add > back the locking which had also been removed by commit e83766334f96 > ("tty: serial: qcom_geni_serial: No need to stop tx/rx on UART > shutdown"). Hmmm, when I look at that commit it makes me think that the problem that commit e83766334f96 ("tty: serial: qcom_geni_serial: No need to stop tx/rx on UART shutdown") was fixing was re-introduced by commit d8aca2f96813 ("tty: serial: qcom-geni-serial: stop operations in progress at shutdown"). ...and indeed, it was. :( I can't interact with kgdb if I do this: 1. ssh over to DUT 2. Kill the console process (on ChromeOS stop console-ttyMSM0) 3. Drop in the debugger (echo g > /proc/sysrq-trigger) This bug predates your series, but since it touches the same code maybe you could fix it at the same time? I will note that commit e83766334f96 ("tty: serial: qcom_geni_serial: No need to stop tx/rx on UART shutdown") mentions that it wasn't required for FIFO mode--only DMA... Aside from the pre-existing bug, I agree that the locking should be there. -Doug
diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c index 9ea6bd09e665..b6a8729cee6d 100644 --- a/drivers/tty/serial/qcom_geni_serial.c +++ b/drivers/tty/serial/qcom_geni_serial.c @@ -1096,10 +1096,12 @@ static void qcom_geni_serial_shutdown(struct uart_port *uport) { disable_irq(uport->irq); + uart_port_lock_irq(uport); qcom_geni_serial_stop_tx(uport); qcom_geni_serial_stop_rx(uport); qcom_geni_serial_cancel_tx_cmd(uport); + uart_port_unlock_irq(uport); } static void qcom_geni_serial_flush_buffer(struct uart_port *uport)
A commit adding back the stopping of tx on port shutdown failed to add back the locking which had also been removed by commit e83766334f96 ("tty: serial: qcom_geni_serial: No need to stop tx/rx on UART shutdown"). Holding the port lock is needed to serialise against the console code, which may update the interrupt enable register and access the port state. Fixes: d8aca2f96813 ("tty: serial: qcom-geni-serial: stop operations in progress at shutdown") Fixes: 947cc4ecc06c ("serial: qcom-geni: fix soft lockup on sw flow control and suspend") Cc: stable@vger.kernel.org # 6.3 Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> Signed-off-by: Johan Hovold <johan+linaro@kernel.org> --- drivers/tty/serial/qcom_geni_serial.c | 2 ++ 1 file changed, 2 insertions(+)