Hi, On Thu, Oct 10, 2024 at 11:51 PM Johan Hovold <johan@xxxxxxxxxx> wrote: > > > > Not sure how your "console process" works, but this should only happen > > > if you do not enable the serial console (console=ttyMSM0) and then try > > > to use a polled console (as enabling the console will prevent port > > > shutdown from being called). > > > > That simply doesn't seem to be the case for me. The port shutdown > > seems to be called. To confirm, I put a printout at the start of > > qcom_geni_serial_shutdown(). I see in my /proc/cmdline: > > > > console=ttyMSM0,115200n8 > > > > ...and I indeed verify that I see console messages on my UART. I then run: > > > > stop console-ttyMSM0 > > > > ...and I see on the UART: > > > > [ 92.916964] DOUG: qcom_geni_serial_shutdown > > [ 92.922703] init: console-ttyMSM0 main process (611) killed by TERM signal > > > > Console messages keep coming out the UART even though the agetty isn't > > there. > > And this is with a Chromium kernel, not mainline? Who do you take me for?!?! :-P :-P :-P Of course it's with mainline. > If you take a look at tty_port_shutdown() there's a hack in there for > consoles that was added back in 2010 and that prevents shutdown() from > called for console ports. > > Put perhaps you manage to hit shutdown() via some other path. Serial > core is not yet using tty_port_hangup() so a hangup might trigger > that... > > Could you check that with a dump_stack()? Sure. Typed from the agetty itself, here ya go. Git hash is not a mainline git hash because I have your patches applied. "dirty" is because of the printout / dump_stack(). lazor-rev9 ~ # stop console-ttyMSM0 [ 68.772828] DOUG: qcom_geni_serial_shutdown [ 68.777365] CPU: 2 UID: 0 PID: 589 Comm: login Not tainted 6.12.0-rc1-g0bde0d120d58-dirty #1 ac8ed1a05abcc73f4fafe0543cbc76768ea594e1 [ 68.789737] Hardware name: Google Lazor (rev9) with LTE (DT) [ 68.795581] Call trace: [ 68.798124] dump_backtrace+0xf8/0x120 [ 68.802025] show_stack+0x24/0x38 [ 68.805463] dump_stack_lvl+0x40/0xc8 [ 68.809265] dump_stack+0x18/0x38 [ 68.812702] qcom_geni_serial_shutdown+0x38/0x110 [ 68.817578] uart_port_shutdown+0x48/0x68 [ 68.821736] uart_shutdown+0xcc/0x170 [ 68.825530] uart_hangup+0x54/0x158 [ 68.829154] __tty_hangup+0x20c/0x318 [ 68.832954] tty_vhangup_session+0x20/0x38 [ 68.837195] disassociate_ctty+0xe8/0x1a8 [ 68.841355] do_exit+0x10c/0x358 [ 68.844716] do_group_exit+0x9c/0xa8 [ 68.848441] get_signal+0x408/0x4d8 [ 68.852071] do_signal+0xa8/0x770 [ 68.855526] do_notify_resume+0x78/0x118 [ 68.859605] el0_svc+0x64/0x68 [ 68.862790] el0t_64_sync_handler+0x20/0x128 [ 68.867218] el0t_64_sync+0x1a8/0x1b0 [ 68.872933] init: console-ttyMSM0 main process (589) killed by TERM signal > > Now I (via ssh) drop into the debugger: > > > > echo g > /proc/sysrq-trigger > > > > I see the "kgdb" prompt but I can't interact with it because > > qcom_geni_serial_shutdown() stopped RX. > > How about simply amending poll_get_char() so that it enables the > receiver if it's not already enabled? Yeah, this would probably work. -Doug
