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serial: amba-pl011: 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.

Cc: Russell King <linux@armlinux.org.uk>
Link: https://lore.kernel.org/r/20240301215246.891055-2-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 22:45:14 +01:00
committed by Kevin Becker
parent 760f99f8e1
commit d57436c19b
1 changed files with 8 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/tty/serial/amba-pl011.c
+8 -16
View File
@@ -348,10 +348,7 @@ static int pl011_fifo_to_tty(struct uart_amba_port *uap)
flag = TTY_FRAME; flag = TTY_FRAME;
} }
uart_port_unlock(&uap->port); sysrq = uart_prepare_sysrq_char(&uap->port, ch & 255);
sysrq = uart_handle_sysrq_char(&uap->port, ch & 255);
uart_port_lock(&uap->port);
if (!sysrq) if (!sysrq)
uart_insert_char(&uap->port, ch, UART011_DR_OE, ch, flag); 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); ret = pl011_dma_rx_trigger_dma(uap);
pl011_dma_rx_chars(uap, pending, lastbuf, false); 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 * Do this check after we picked the DMA chars so we don't
* get some IRQ immediately from RX. * 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) static irqreturn_t pl011_int(int irq, void *dev_id)
{ {
struct uart_amba_port *uap = dev_id; struct uart_amba_port *uap = dev_id;
unsigned long flags;
unsigned int status, pass_counter = AMBA_ISR_PASS_LIMIT; unsigned int status, pass_counter = AMBA_ISR_PASS_LIMIT;
int handled = 0; int handled = 0;
uart_port_lock_irqsave(&uap->port, &flags); uart_port_lock(&uap->port);
status = pl011_read(uap, REG_RIS) & uap->im; status = pl011_read(uap, REG_RIS) & uap->im;
if (status) { if (status) {
do { do {
@@ -1573,7 +1569,7 @@ static irqreturn_t pl011_int(int irq, void *dev_id)
handled = 1; handled = 1;
} }
uart_port_unlock_irqrestore(&uap->port, flags); uart_unlock_and_check_sysrq(&uap->port);
return IRQ_RETVAL(handled); return IRQ_RETVAL(handled);
} }
@@ -2329,13 +2325,10 @@ pl011_console_write(struct console *co, const char *s, unsigned int count)
clk_enable(uap->clk); clk_enable(uap->clk);
local_irq_save(flags); if (oops_in_progress)
if (uap->port.sysrq) locked = uart_port_trylock_irqsave(&uap->port, &flags);
locked = 0;
else if (oops_in_progress)
locked = uart_port_trylock(&uap->port);
else else
uart_port_lock(&uap->port); uart_port_lock_irqsave(&uap->port, &flags);
/* /*
* First save the CR then disable the interrupts * First save the CR then disable the interrupts
@@ -2361,8 +2354,7 @@ pl011_console_write(struct console *co, const char *s, unsigned int count)
pl011_write(old_cr, uap, REG_CR); pl011_write(old_cr, uap, REG_CR);
if (locked) if (locked)
uart_port_unlock(&uap->port); uart_port_unlock_irqrestore(&uap->port, flags);
local_irq_restore(flags);
clk_disable(uap->clk); clk_disable(uap->clk);
} }