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authorRabin Vincent <rabin.vincent@stericsson.com>2012-01-17 11:52:28 +0100
committerGreg Kroah-Hartman <gregkh@suse.de>2012-01-24 16:09:55 -0800
commitef605fdb33883d687cff5ba75095a91b313b4966 (patch)
tree7eea2b5b397d0b5373ec76035bf924d3885b2489 /drivers/tty/serial/amba-pl011.c
parentd8d8ffa477831b713ddfa2ad4d0ca545f3b567e5 (diff)
serial: amba-pl011: lock console writes against interrupts
Protect against pl011_console_write() and the interrupt for the console UART running concurrently on different CPUs. Otherwise the console_write could spin for a long time waiting for the UART to become not busy, while the other CPU continuously services UART interrupts and keeps the UART busy. The checks for sysrq and oops_in_progress are taken from 8250.c. Cc: stable <stable@vger.kernel.org> Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com> Reviewed-by: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com> Reviewed-by: Bibek Basu <bibek.basu@stericsson.com> Reviewed-by: Shreshtha Kumar Sahu <shreshthakumar.sahu@stericsson.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/tty/serial/amba-pl011.c')
-rw-r--r--drivers/tty/serial/amba-pl011.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index ce843d058e0..6800f5f2624 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1751,9 +1751,19 @@ pl011_console_write(struct console *co, const char *s, unsigned int count)
{
struct uart_amba_port *uap = amba_ports[co->index];
unsigned int status, old_cr, new_cr;
+ unsigned long flags;
+ int locked = 1;
clk_enable(uap->clk);
+ local_irq_save(flags);
+ if (uap->port.sysrq)
+ locked = 0;
+ else if (oops_in_progress)
+ locked = spin_trylock(&uap->port.lock);
+ else
+ spin_lock(&uap->port.lock);
+
/*
* First save the CR then disable the interrupts
*/
@@ -1773,6 +1783,10 @@ pl011_console_write(struct console *co, const char *s, unsigned int count)
} while (status & UART01x_FR_BUSY);
writew(old_cr, uap->port.membase + UART011_CR);
+ if (locked)
+ spin_unlock(&uap->port.lock);
+ local_irq_restore(flags);
+
clk_disable(uap->clk);
}