From: Fugang Duan <[email protected]>
commit e67c139c488e84e7eae6c333231e791f0e89b3fb upstream.
For below code, there has chance to cause deadlock in SMP system:
Thread 1:
clk_enable_lock();
pr_info("debug message");
clk_enable_unlock();
Thread 2:
imx_uart_console_write()
clk_enable()
clk_enable_lock();
Thread 1:
Acuired clk enable_lock -> printk -> console_trylock_spinning
Thread 2:
console_unlock() -> imx_uart_console_write -> clk_disable -> Acquite clk
enable_lock
So the patch is to keep console port clocks always on like
other console drivers.
Fixes: 1cf93e0d5488 ("serial: imx: remove the uart_console() check")
Acked-by: Uwe Kleine-König <[email protected]>
Signed-off-by: Fugang Duan <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Cc: stable <[email protected]>
[fix up build warning - gregkh]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/tty/serial/imx.c | 20 +++-----------------
1 file changed, 3 insertions(+), 17 deletions(-)
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1942,16 +1942,6 @@ imx_uart_console_write(struct console *c
unsigned int ucr1;
unsigned long flags = 0;
int locked = 1;
- int retval;
-
- retval = clk_enable(sport->clk_per);
- if (retval)
- return;
- retval = clk_enable(sport->clk_ipg);
- if (retval) {
- clk_disable(sport->clk_per);
- return;
- }
if (sport->port.sysrq)
locked = 0;
@@ -1987,9 +1977,6 @@ imx_uart_console_write(struct console *c
if (locked)
spin_unlock_irqrestore(&sport->port.lock, flags);
-
- clk_disable(sport->clk_ipg);
- clk_disable(sport->clk_per);
}
/*
@@ -2090,15 +2077,14 @@ imx_uart_console_setup(struct console *c
retval = uart_set_options(&sport->port, co, baud, parity, bits, flow);
- clk_disable(sport->clk_ipg);
if (retval) {
- clk_unprepare(sport->clk_ipg);
+ clk_disable_unprepare(sport->clk_ipg);
goto error_console;
}
- retval = clk_prepare(sport->clk_per);
+ retval = clk_prepare_enable(sport->clk_per);
if (retval)
- clk_unprepare(sport->clk_ipg);
+ clk_disable_unprepare(sport->clk_ipg);
error_console:
return retval;
