Re: panic_cpu should be volatile

On Thursday, October 07, 2010 1:40:49 pm Andriy Gapon wrote: > > panic_cpu variable in kern_shutdown.c should be volatile otherwise it's > cached in > a register in the innermost while-loop in this code (observed on amd64 with > base > gcc and -O2): > if (panic_cpu != PCPU_GET(cpuid)) >

panic_cpu should be volatile

panic_cpu variable in kern_shutdown.c should be volatile otherwise it's cached in a register in the innermost while-loop in this code (observed on amd64 with base gcc and -O2): if (panic_cpu != PCPU_GET(cpuid)) while (atomic_cmpset_int(&panic_cpu, NOCPU, PCPU_GET(cpuid)) == 0)