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serial: bcm63xx: Use uart_prepare_sysrq_char().

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BugLink: https://bugs.launchpad.net/bugs/2060704

The port lock is a spinlock_t which is becomes a sleeping lock on PREEMPT_RT.
The driver splits the locking function into two parts: local_irq_save() and
uart_port_lock() and this breaks PREEMPT_RT.

Delay handling sysrq until port lock is dropped.
Remove the special case in the console write routine an always use the
complete locking function.

Link: https://lore.kernel.org/r/20240301215246.891055-4-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Kevin Becker <kevin.becker@canonical.com>
This commit is contained in:
Sebastian Andrzej Siewior
2024-03-01 22:45:16 +01:00
committed by Kevin Becker
parent d23f286d2c
commit 973fcfdec7
1 changed files with 8 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/tty/serial/bcm63xx_uart.c
+8 -16
View File
@@ -285,10 +285,9 @@ static void bcm_uart_do_rx(struct uart_port *port)
flag = TTY_PARITY;
}
if (uart_handle_sysrq_char(port, c))
if (uart_prepare_sysrq_char(port, c))
continue;
if ((cstat & port->ignore_status_mask) == 0)
tty_insert_flip_char(tty_port, c, flag);
@@ -356,7 +355,7 @@ static irqreturn_t bcm_uart_interrupt(int irq, void *dev_id)
estat & UART_EXTINP_DCD_MASK);
}
uart_port_unlock(port);
uart_unlock_and_check_sysrq(port);
return IRQ_HANDLED;
}
@@ -706,20 +705,14 @@ static void bcm_console_write(struct console *co, const char *s,
{
struct uart_port *port;
unsigned long flags;
int locked;
int locked = 1;
port = &ports[co->index];
local_irq_save(flags);
if (port->sysrq) {
/* bcm_uart_interrupt() already took the lock */
locked = 0;
} else if (oops_in_progress) {
locked = uart_port_trylock(port);
} else {
uart_port_lock(port);
locked = 1;
}
if (oops_in_progress)
locked = uart_port_trylock_irqsave(port, &flags);
else
uart_port_lock_irqsave(port, &flags);
/* call helper to deal with \r\n */
uart_console_write(port, s, count, bcm_console_putchar);
@@ -728,8 +721,7 @@ static void bcm_console_write(struct console *co, const char *s,
wait_for_xmitr(port);
if (locked)
uart_port_unlock(port);
local_irq_restore(flags);
uart_port_unlock_irqrestore(port, flags);
}
/*