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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>
This commit is contained in:
Jun Chen 2012-10-22 10:23:07 -04:00 committed by Greg Kroah-Hartman
parent 319fb0d219
commit c73ba2ae43
1 changed files with 1 additions and 3 deletions
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4
drivers/tty/serial/ifx6x60.c
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@ -231,9 +231,7 @@ static void mrdy_assert(struct ifx_spi_device *ifx_dev)
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);
}
}