serial: ifx6x60: add_timer is not safe in the mrdy_assert function
This patch make use of mod_timer instead of add_timer in the mrdy_assert function.
Because the srdy interrupter can go high when we are running function mrdy_assert and mrdy_assert
can be called by multi-entry. In our medfield platform, spi stress test can encounter this
error logs triggered by the BUG_ON of add_timer function.This patch had been tested on
our medfield platform.
the scenario:
CPU0 CPU1
mrdy_assert
set_bit(IFX_SPI_STATE_TIMER_PENDING)
ifx_spi_handle_srdy
...
clear_bit(IFX_SPI_STATE_TIMER_PENDING)
...
mrdy_assert
set_bit(IFX_SPI_STATE_TIMER_PENDING)
...
add_timer
...
add_timer
Cc: liu chuansheng <chuansheng.liu@intel.com>
Cc: Bi Chao <chao.bi@intel.com>
Signed-off-by: Chen Jun <jun.d.chen@intel.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/serial/ifx6x60.c b/drivers/tty/serial/ifx6x60.c
index 2d2bcbd..4b001ea 100644
--- a/drivers/tty/serial/ifx6x60.c
+++ b/drivers/tty/serial/ifx6x60.c
@@ -231,9 +231,7 @@
if (!val) {
if (!test_and_set_bit(IFX_SPI_STATE_TIMER_PENDING,
&ifx_dev->flags)) {
- ifx_dev->spi_timer.expires =
- jiffies + IFX_SPI_TIMEOUT_SEC*HZ;
- add_timer(&ifx_dev->spi_timer);
+ mod_timer(&ifx_dev->spi_timer,jiffies + IFX_SPI_TIMEOUT_SEC*HZ);
}
}