From: Thomas Gleixner Date: Thu, 14 Sep 2023 20:44:00 +0206 Subject: [PATCH 043/134] serial: omap: Use port lock wrappers Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz When a serial port is used for kernel console output, then all modifications to the UART registers which are done from other contexts, e.g. getty, termios, are interference points for the kernel console. So far this has been ignored and the printk output is based on the principle of hope. The rework of the console infrastructure which aims to support threaded and atomic consoles, requires to mark sections which modify the UART registers as unsafe. This allows the atomic write function to make informed decisions and eventually to restore operational state. It also allows to prevent the regular UART code from modifying UART registers while printk output is in progress. All modifications of UART registers are guarded by the UART port lock, which provides an obvious synchronization point with the console infrastructure. To avoid adding this functionality to all UART drivers, wrap the spin_[un]lock*() invocations for uart_port::lock into helper functions which just contain the spin_[un]lock*() invocations for now. In a subsequent step these helpers will gain the console synchronization mechanisms. Converted with coccinelle. No functional change. Signed-off-by: Thomas Gleixner Signed-off-by: John Ogness Link: https://lore.kernel.org/r/20230914183831.587273-44-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sebastian Andrzej Siewior --- drivers/tty/serial/omap-serial.c | 38 +++++++++++++++++++------------------- 1 file changed, 19 insertions(+), 19 deletions(-) --- a/drivers/tty/serial/omap-serial.c +++ b/drivers/tty/serial/omap-serial.c @@ -390,10 +390,10 @@ static void serial_omap_throttle(struct struct uart_omap_port *up = to_uart_omap_port(port); unsigned long flags; - spin_lock_irqsave(&up->port.lock, flags); + uart_port_lock_irqsave(&up->port, &flags); up->ier &= ~(UART_IER_RLSI | UART_IER_RDI); serial_out(up, UART_IER, up->ier); - spin_unlock_irqrestore(&up->port.lock, flags); + uart_port_unlock_irqrestore(&up->port, flags); } static void serial_omap_unthrottle(struct uart_port *port) @@ -401,10 +401,10 @@ static void serial_omap_unthrottle(struc struct uart_omap_port *up = to_uart_omap_port(port); unsigned long flags; - spin_lock_irqsave(&up->port.lock, flags); + uart_port_lock_irqsave(&up->port, &flags); up->ier |= UART_IER_RLSI | UART_IER_RDI; serial_out(up, UART_IER, up->ier); - spin_unlock_irqrestore(&up->port.lock, flags); + uart_port_unlock_irqrestore(&up->port, flags); } static unsigned int check_modem_status(struct uart_omap_port *up) @@ -527,7 +527,7 @@ static irqreturn_t serial_omap_irq(int i irqreturn_t ret = IRQ_NONE; int max_count = 256; - spin_lock(&up->port.lock); + uart_port_lock(&up->port); do { iir = serial_in(up, UART_IIR); @@ -563,7 +563,7 @@ static irqreturn_t serial_omap_irq(int i } } while (max_count--); - spin_unlock(&up->port.lock); + uart_port_unlock(&up->port); tty_flip_buffer_push(&up->port.state->port); @@ -579,9 +579,9 @@ static unsigned int serial_omap_tx_empty unsigned int ret = 0; dev_dbg(up->port.dev, "serial_omap_tx_empty+%d\n", up->port.line); - spin_lock_irqsave(&up->port.lock, flags); + uart_port_lock_irqsave(&up->port, &flags); ret = serial_in(up, UART_LSR) & UART_LSR_TEMT ? TIOCSER_TEMT : 0; - spin_unlock_irqrestore(&up->port.lock, flags); + uart_port_unlock_irqrestore(&up->port, flags); return ret; } @@ -647,13 +647,13 @@ static void serial_omap_break_ctl(struct unsigned long flags; dev_dbg(up->port.dev, "serial_omap_break_ctl+%d\n", up->port.line); - spin_lock_irqsave(&up->port.lock, flags); + uart_port_lock_irqsave(&up->port, &flags); if (break_state == -1) up->lcr |= UART_LCR_SBC; else up->lcr &= ~UART_LCR_SBC; serial_out(up, UART_LCR, up->lcr); - spin_unlock_irqrestore(&up->port.lock, flags); + uart_port_unlock_irqrestore(&up->port, flags); } static int serial_omap_startup(struct uart_port *port) @@ -701,13 +701,13 @@ static int serial_omap_startup(struct ua * Now, initialize the UART */ serial_out(up, UART_LCR, UART_LCR_WLEN8); - spin_lock_irqsave(&up->port.lock, flags); + uart_port_lock_irqsave(&up->port, &flags); /* * Most PC uarts need OUT2 raised to enable interrupts. */ up->port.mctrl |= TIOCM_OUT2; serial_omap_set_mctrl(&up->port, up->port.mctrl); - spin_unlock_irqrestore(&up->port.lock, flags); + uart_port_unlock_irqrestore(&up->port, flags); up->msr_saved_flags = 0; /* @@ -742,10 +742,10 @@ static void serial_omap_shutdown(struct up->ier = 0; serial_out(up, UART_IER, 0); - spin_lock_irqsave(&up->port.lock, flags); + uart_port_lock_irqsave(&up->port, &flags); up->port.mctrl &= ~TIOCM_OUT2; serial_omap_set_mctrl(&up->port, up->port.mctrl); - spin_unlock_irqrestore(&up->port.lock, flags); + uart_port_unlock_irqrestore(&up->port, flags); /* * Disable break condition and FIFOs @@ -815,7 +815,7 @@ serial_omap_set_termios(struct uart_port * Ok, we're now changing the port state. Do it with * interrupts disabled. */ - spin_lock_irqsave(&up->port.lock, flags); + uart_port_lock_irqsave(&up->port, &flags); /* * Update the per-port timeout. @@ -1013,7 +1013,7 @@ serial_omap_set_termios(struct uart_port serial_omap_set_mctrl(&up->port, up->port.mctrl); - spin_unlock_irqrestore(&up->port.lock, flags); + uart_port_unlock_irqrestore(&up->port, flags); dev_dbg(up->port.dev, "serial_omap_set_termios+%d\n", up->port.line); } @@ -1216,9 +1216,9 @@ serial_omap_console_write(struct console if (up->port.sysrq) locked = 0; else if (oops_in_progress) - locked = spin_trylock(&up->port.lock); + locked = uart_port_trylock(&up->port); else - spin_lock(&up->port.lock); + uart_port_lock(&up->port); /* * First save the IER then disable the interrupts @@ -1245,7 +1245,7 @@ serial_omap_console_write(struct console check_modem_status(up); if (locked) - spin_unlock(&up->port.lock); + uart_port_unlock(&up->port); local_irq_restore(flags); }