On 06/25/2007 05:38 PM, Loic Prylli wrote: [cc: Andi]
> Processors synchronization in set_mtrr requires the .gate field > to be set after .count field is properly initialized. Without an explicit > barrier, the compiler was reordering those memory stores. That was sometimes > causing a processor (in ipi_handler) to see the .gate change and > decrement .count before the latter is set by set_mtrr() (which > then hangs in a infinite loop with irqs disabled). > > Signed-off-by: Loic Prylli <[EMAIL PROTECTED]> > --- > arch/i386/kernel/cpu/mtrr/main.c | 4 ++++ > 1 files changed, 4 insertions(+), 0 deletions(-) > > diff --git a/arch/i386/kernel/cpu/mtrr/main.c > b/arch/i386/kernel/cpu/mtrr/main.c > index 55b0051..75dc6d5 100644 > --- a/arch/i386/kernel/cpu/mtrr/main.c > +++ b/arch/i386/kernel/cpu/mtrr/main.c > @@ -229,6 +229,8 @@ static void set_mtrr(unsigned int reg, unsigned long base, > data.smp_size = size; > data.smp_type = type; > atomic_set(&data.count, num_booting_cpus() - 1); > + /* make sure data.count is visible before unleashing other CPUs */ > + smp_wmb(); > atomic_set(&data.gate,0); > > /* Start the ball rolling on other CPUs */ > @@ -242,6 +244,7 @@ static void set_mtrr(unsigned int reg, unsigned long base, > > /* ok, reset count and toggle gate */ > atomic_set(&data.count, num_booting_cpus() - 1); > + smp_wmb(); > atomic_set(&data.gate,1); > > /* do our MTRR business */ > @@ -260,6 +263,7 @@ static void set_mtrr(unsigned int reg, unsigned long base, > cpu_relax(); > > atomic_set(&data.count, num_booting_cpus() - 1); > + smp_wmb(); > atomic_set(&data.gate,0); > > /* - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
