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serial: amba-pl011: Use uart_prepare_sysrq_char().

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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.

Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20240301215246.891055-2-bigeasy@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sebastian Andrzej Siewior 2024-03-01 22:45:14 +01:00 committed by Greg Kroah-Hartman
parent 65295eba19
commit 2432f71c22
1 changed files with 8 additions and 16 deletions
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24
drivers/tty/serial/amba-pl011.c
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@ -348,10 +348,7 @@ static int pl011_fifo_to_tty(struct uart_amba_port *uap)
flag = TTY_FRAME;
}
uart_port_unlock(&uap->port);
sysrq = uart_handle_sysrq_char(&uap->port, ch & 255);
uart_port_lock(&uap->port);
sysrq = uart_prepare_sysrq_char(&uap->port, ch & 255);
if (!sysrq)
uart_insert_char(&uap->port, ch, UART011_DR_OE, ch, flag);
}
@ -1017,7 +1014,7 @@ static void pl011_dma_rx_callback(void *data)
ret = pl011_dma_rx_trigger_dma(uap);
pl011_dma_rx_chars(uap, pending, lastbuf, false);
uart_port_unlock_irq(&uap->port);
uart_unlock_and_check_sysrq(&uap->port);
/*
* Do this check after we picked the DMA chars so we don't
* get some IRQ immediately from RX.
@ -1540,11 +1537,10 @@ static void check_apply_cts_event_workaround(struct uart_amba_port *uap)
static irqreturn_t pl011_int(int irq, void *dev_id)
{
struct uart_amba_port *uap = dev_id;
unsigned long flags;
unsigned int status, pass_counter = AMBA_ISR_PASS_LIMIT;
int handled = 0;
uart_port_lock_irqsave(&uap->port, &flags);
uart_port_lock(&uap->port);
status = pl011_read(uap, REG_RIS) & uap->im;
if (status) {
do {
@ -1573,7 +1569,7 @@ static irqreturn_t pl011_int(int irq, void *dev_id)
handled = 1;
}
uart_port_unlock_irqrestore(&uap->port, flags);
uart_unlock_and_check_sysrq(&uap->port);
return IRQ_RETVAL(handled);
}
@ -2322,13 +2318,10 @@ pl011_console_write(struct console *co, const char *s, unsigned int count)
clk_enable(uap->clk);
local_irq_save(flags);
if (uap->port.sysrq)
locked = 0;
else if (oops_in_progress)
locked = uart_port_trylock(&uap->port);
if (oops_in_progress)
locked = uart_port_trylock_irqsave(&uap->port, &flags);
else
uart_port_lock(&uap->port);
uart_port_lock_irqsave(&uap->port, &flags);
/*
* First save the CR then disable the interrupts
@ -2354,8 +2347,7 @@ pl011_console_write(struct console *co, const char *s, unsigned int count)
pl011_write(old_cr, uap, REG_CR);
if (locked)
uart_port_unlock(&uap->port);
local_irq_restore(flags);
uart_port_unlock_irqrestore(&uap->port, flags);
clk_disable(uap->clk);
}