tty: serial: imx: keep console clocks always on (e67c139c) · Commits · 戴 / test

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: ("serial: imx: remove the uart_console() check") Acked-by:

Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by:

Fugang Duan <fugang.duan@nxp.com> Link: https://lore.kernel.org/r/20201111025136.29818-1-fugang.duan@nxp.com Cc: stable <stable@vger.kernel.org> [fix up build warning - gregkh] Signed-off-by:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/imx.c

+3 −17

Original line number	Diff line number	Diff line
		@@ -2008,16 +2008,6 @@ imx_uart_console_write(struct console co, const char s, unsigned int count)
		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;
		@@ -2053,9 +2043,6 @@ imx_uart_console_write(struct console co, const char s, unsigned int count)

		if (locked)
		spin_unlock_irqrestore(&sport->port.lock, flags);

		clk_disable(sport->clk_ipg);
		clk_disable(sport->clk_per);
		}

		/*
		@@ -2156,15 +2143,14 @@ imx_uart_console_setup(struct console co, char options)

		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;

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