Messages in this thread | | | Subject | Re: [PATCH v2 1/8] RISC-V: Do not wait indefinitely in __cpu_up | From | Atish Patra <> | Date | Thu, 17 Jan 2019 18:35:39 -0800 |
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On 1/15/19 5:51 AM, Christoph Hellwig wrote: >> >> void *__cpu_up_stack_pointer[NR_CPUS]; >> void *__cpu_up_task_pointer[NR_CPUS]; >> +static DECLARE_COMPLETION(cpu_running); >> >> void __init smp_prepare_boot_cpu(void) >> { >> @@ -81,6 +82,7 @@ void __init setup_smp(void) >> >> int __cpu_up(unsigned int cpu, struct task_struct *tidle) >> { >> + int ret = 0; >> int hartid = cpuid_to_hartid_map(cpu); >> tidle->thread_info.cpu = cpu; >> >> @@ -96,10 +98,15 @@ int __cpu_up(unsigned int cpu, struct task_struct *tidle) >> task_stack_page(tidle) + THREAD_SIZE); >> WRITE_ONCE(__cpu_up_task_pointer[hartid], tidle); >> >> - while (!cpu_online(cpu)) >> - cpu_relax(); >> + wait_for_completion_timeout(&cpu_running, >> + msecs_to_jiffies(1000)); > > Having a global completion here worries me. I bet we have some higher > level serialization, but can we comment or even better lockdep assert on > that? >
Yes. It is serialized from smp.c in smp_init(). It brings one cpu online at a time for preset_cpu mask.
Do we still need a lockdep assert ?
Regards, Atish > Also please use up your available lines (72 in commit logs, 80 in source > files) instead of adding spurious line wraps. > > _______________________________________________ > linux-riscv mailing list > linux-riscv@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv >
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