[GEODE] fix a race condition in the MFGPT timer tick From: Jordan Crouse When we set the MFGPT timer tick, there is a chance that we'll immediately assert an event. If for some reason the IRQ routing for this clock has been setup for some other purpose, then we could end up firing an interrupt into the SMM handler or worse. This rearranges the timer tick init function to initalize the handler before we set up the MFGPT clock to make sure that even if we get an event, it will go to the handler. Furthermore, in the handler we need to make sure that we clear the event, even if the timer isn't running. Signed-off-by: Jordan Crouse --- arch/x86/kernel/mfgpt_32.c | 9 +++++---- 1 files changed, 5 insertions(+), 4 deletions(-) Index: git/arch/x86/kernel/mfgpt_32.c =================================================================== --- git.orig/arch/x86/kernel/mfgpt_32.c 2008-01-21 17:09:54.000000000 -0700 +++ git/arch/x86/kernel/mfgpt_32.c 2008-01-22 12:21:21.000000000 -0700 @@ -278,12 +278,12 @@ static irqreturn_t mfgpt_tick(int irq, void *dev_id) { + /* Turn off the clock (and clear the event) */ + mfgpt_disable_timer(mfgpt_event_clock); + if (mfgpt_tick_mode == CLOCK_EVT_MODE_SHUTDOWN) return IRQ_HANDLED; - /* Turn off the clock */ - mfgpt_disable_timer(mfgpt_event_clock); - /* Clear the counter */ geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_COUNTER, 0); @@ -319,10 +319,6 @@ } mfgpt_event_clock = timer; - /* Set the clock scale and enable the event mode for CMP2 */ - val = MFGPT_SCALE | (3 << 8); - - geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_SETUP, val); /* Set up the IRQ on the MFGPT side */ if (geode_mfgpt_setup_irq(mfgpt_event_clock, MFGPT_CMP2, irq)) { @@ -339,6 +335,11 @@ goto err; } + /* Set the clock scale and enable the event mode for CMP2 */ + val = MFGPT_SCALE | (3 << 8); + + geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_SETUP, val); + /* Set up the clock event */ mfgpt_clockevent.mult = div_sc(MFGPT_HZ, NSEC_PER_SEC, 32); mfgpt_clockevent.min_delta_ns = clockevent_delta2ns(0xF,