From 667984d9e481e43a930a478c588dced98cb61fea Mon Sep 17 00:00:00 2001 From: Jordan Crouse Date: Tue, 22 Jan 2008 23:30:16 +0100 Subject: [PATCH] x86: GEODE fix a race condition in the MFGPT timer tick 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 Signed-off-by: Thomas Gleixner Acked-by: Ingo Molnar Tested-by: Arnd Hannemann --- arch/x86/kernel/mfgpt_32.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/arch/x86/kernel/mfgpt_32.c b/arch/x86/kernel/mfgpt_32.c index 0ab680f2d9db..3960ab7e1497 100644 --- a/arch/x86/kernel/mfgpt_32.c +++ b/arch/x86/kernel/mfgpt_32.c @@ -278,12 +278,12 @@ static int mfgpt_next_event(unsigned long delta, struct clock_event_device *evt) 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 @@ static int __init mfgpt_timer_setup(void) } 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 @@ static int __init mfgpt_timer_setup(void) 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, -- 2.20.1