From: Anup Patel <anup@brainfault.org>
To: Atish Patra <atish.patra@wdc.com>
Cc: "Rob Herring" <robh@kernel.org>, "Patrick Stählin" <me@packi.ch>,
"Albert Ou" <aou@eecs.berkeley.edu>,
"Jason Cooper" <jason@lakedaemon.net>,
"Dmitriy Cherkasov" <dmitriy@oss-tech.org>,
"Damien Le Moal" <Damien.LeMoal@wdc.com>,
"Daniel Lezcano" <daniel.lezcano@linaro.org>,
"linux-kernel@vger.kernel.org List"
<linux-kernel@vger.kernel.org>,
"Michael Clark" <michaeljclark@mac.com>,
"Marc Zyngier" <marc.zyngier@arm.com>,
"Palmer Dabbelt" <palmer@sifive.com>,
linux-riscv@lists.infradead.org,
"Thomas Gleixner" <tglx@linutronix.de>
Subject: Re: [PATCH 1/3] RISC-V: Do not wait indefinitely in __cpu_up
Date: Thu, 27 Dec 2018 09:06:24 +0530 [thread overview]
Message-ID: <CAAhSdy3Wd6tPrv-XDqETK8sBetYSg-mjHzZXJQJgUFeufEjPfA@mail.gmail.com> (raw)
In-Reply-To: <1545865741-22795-2-git-send-email-atish.patra@wdc.com>
On Thu, Dec 27, 2018 at 4:39 AM Atish Patra <atish.patra@wdc.com> wrote:
>
> In SMP path, __cpu_up waits for other CPU to come online
> indefinitely. This is wrong as other CPU might be disabled
> in machine mode and possible CPU is set to the cpus present
> in DT.
>
> Introduce a completion variable and waits only for a second.
>
> Signed-off-by: Atish Patra <atish.patra@wdc.com>
> ---
> arch/riscv/kernel/smpboot.c | 14 +++++++++++---
> 1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
> index 18cda0e8..bb8cd242 100644
> --- a/arch/riscv/kernel/smpboot.c
> +++ b/arch/riscv/kernel/smpboot.c
> @@ -39,6 +39,7 @@
>
> 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)
> {
> @@ -77,6 +78,7 @@ 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;
>
> @@ -92,10 +94,15 @@ 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));
>
> - return 0;
> + if (!cpu_online(cpu)) {
> + pr_crit("CPU%u: failed to come online\n", cpu);
> + ret = -EIO;
> + }
> +
> + return ret;
> }
>
> void __init smp_cpus_done(unsigned int max_cpus)
> @@ -121,6 +128,7 @@ asmlinkage void __init smp_callin(void)
> * a local TLB flush right now just in case.
> */
> local_flush_tlb_all();
> + complete(&cpu_running);
> /*
> * Disable preemption before enabling interrupts, so we don't try to
> * schedule a CPU that hasn't actually started yet.
> --
> 2.7.4
>
Looks good to me.
Reviewed-by: Anup Patel <anup@brainfault.org>
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next prev parent reply other threads:[~2018-12-27 3:36 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-26 23:08 [PATCH 0/3] Non-smp configuration fix Atish Patra
2018-12-26 23:08 ` [PATCH 1/3] RISC-V: Do not wait indefinitely in __cpu_up Atish Patra
2018-12-27 3:36 ` Anup Patel [this message]
2018-12-26 23:09 ` [PATCH 2/3] RISC-V: Move cpuid to hartid mapping to SMP Atish Patra
2018-12-27 3:37 ` Anup Patel
2019-01-06 2:13 ` Atish Patra
2018-12-26 23:09 ` [PATCH 3/3] RISC-V: Fix non-smp kernel boot on SMP systems Atish Patra
2018-12-27 3:58 ` Anup Patel
2019-01-06 2:14 ` Atish Patra
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