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| author | Rabin Vincent <rabin.vincent@stericsson.com> | 2012-01-17 11:52:28 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2012-01-24 16:09:55 -0800 |
| commit | ef605fdb33883d687cff5ba75095a91b313b4966 (patch) | |
| tree | 7eea2b5b397d0b5373ec76035bf924d3885b2489 | |
| parent | d8d8ffa477831b713ddfa2ad4d0ca545f3b567e5 (diff) | |
| download | linux-ef605fdb33883d687cff5ba75095a91b313b4966.tar.gz linux-ef605fdb33883d687cff5ba75095a91b313b4966.tar.bz2 linux-ef605fdb33883d687cff5ba75095a91b313b4966.zip | |
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>
| -rw-r--r-- | drivers/tty/serial/amba-pl011.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index ce843d058e02..6800f5f26241 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); } |