Hi Johan,
On 30/09/2021 04:54, Johan Hovold wrote:
This is just so broken; you can't just drop the lock. And you clearly
haven't even tried to understand how uart_unlock_and_check_sysrq()
works.
Please take a closer look at the commit you're trying to mimic.
Thanks for the feedback.
I have changed it to:
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 8b121cd869e9..b7cda50602d5 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -803,7 +803,7 @@ static irqreturn_t __imx_uart_rxint(int irq, void
*dev_id)
continue;
}
- if (uart_handle_sysrq_char(&sport->port, (unsigned char)rx))
+ if (uart_prepare_sysrq_char(&sport->port, rx))
continue;
if (unlikely(rx & URXD_ERR)) {
@@ -844,6 +844,7 @@ static irqreturn_t __imx_uart_rxint(int irq, void
*dev_id)
}
out:
+ uart_unlock_and_check_sysrq(&sport->port);
tty_flip_buffer_push(port);
return IRQ_HANDLED;
@@ -959,6 +960,7 @@ static irqreturn_t imx_uart_int(int irq, void
*dev_id)
imx_uart_writel(sport, USR1_AGTIM, USR1);
__imx_uart_rxint(irq, dev_id);
+ spin_lock(&sport->port.lock);
ret = IRQ_HANDLED;
}
@@ -1977,9 +1979,7 @@ imx_uart_console_write(struct console *co, const
char *s, unsigned int count)
unsigned int ucr1;
int locked = 1;
- if (sport->port.sysrq)
- locked = 0;
- else if (oops_in_progress)
+ if (oops_in_progress)
locked = spin_trylock_irqsave(&sport->port.lock, flags);
else
spin_lock_irqsave(&sport->port.lock, flags);
This makes the deadlock not happen after running:
echo t > /proc/sysrq-trigger
, but entering <break> + t via the console does not work anymore.
It returns the sysrq help instead:
sysrq: HELP : loglevel(0-9) reboot(b) crash(c) show-all-locks(d)
terminate-all-tasks(e) memory-full-oom-kill(f) kill-all-tasks(i)
thaw-filesystems(j) sak(k) show-backtrace-all-active-cpu
s(l) show-memory-usage(m) nice-all-RT-tasks(n) poweroff(o)
show-registers(p) show-all-timers(q) unraw(r) sync(s)
show-task-states(t) unmount(u) show-blocked-tasks(w)
dump-ftrace-buffer(z)
Thanks
