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From: Christoph Hellwig <hch@infradead.org>
To: Atish Patra <atish.patra@wdc.com>
Cc: linux-riscv@lists.infradead.org, "Patrick Stählin" <me@packi.ch>,
	"Albert Ou" <aou@eecs.berkeley.edu>,
	"Jason Cooper" <jason@lakedaemon.net>,
	"Alan Kao" <alankao@andestech.com>,
	"Dmitriy Cherkasov" <dmitriy@oss-tech.org>,
	"Anup Patel" <anup@brainfault.org>,
	"Daniel Lezcano" <daniel.lezcano@linaro.org>,
	linux-kernel@vger.kernel.org,
	"Michael Clark" <michaeljclark@mac.com>,
	"Palmer Dabbelt" <palmer@sifive.com>,
	"Andreas Schwab" <schwab@suse.de>,
	"Marc Zyngier" <marc.zyngier@arm.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Zong Li" <zongbox@gmail.com>
Subject: Re: [PATCH v2 1/8] RISC-V: Do not wait indefinitely in __cpu_up
Date: Tue, 15 Jan 2019 05:51:25 -0800	[thread overview]
Message-ID: <20190115135125.GA28946@infradead.org> (raw)
In-Reply-To: <1546940318-9752-2-git-send-email-atish.patra@wdc.com>

>  
>  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?

Also please use up your available lines (72 in commit logs, 80 in source
files) instead of adding spurious line wraps.

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@infradead.org>
To: Atish Patra <atish.patra@wdc.com>
Cc: "Patrick Stählin" <me@packi.ch>,
	"Albert Ou" <aou@eecs.berkeley.edu>,
	"Jason Cooper" <jason@lakedaemon.net>,
	"Alan Kao" <alankao@andestech.com>,
	"Dmitriy Cherkasov" <dmitriy@oss-tech.org>,
	"Anup Patel" <anup@brainfault.org>,
	"Daniel Lezcano" <daniel.lezcano@linaro.org>,
	linux-kernel@vger.kernel.org,
	"Michael Clark" <michaeljclark@mac.com>,
	"Marc Zyngier" <marc.zyngier@arm.com>,
	"Palmer Dabbelt" <palmer@sifive.com>,
	"Andreas Schwab" <schwab@suse.de>,
	linux-riscv@lists.infradead.org,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Zong Li" <zongbox@gmail.com>
Subject: Re: [PATCH v2 1/8] RISC-V: Do not wait indefinitely in __cpu_up
Date: Tue, 15 Jan 2019 05:51:25 -0800	[thread overview]
Message-ID: <20190115135125.GA28946@infradead.org> (raw)
In-Reply-To: <1546940318-9752-2-git-send-email-atish.patra@wdc.com>

>  
>  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?

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

  reply	other threads:[~2019-01-15 13:51 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-08  9:38 [PATCH v2 0/8] Various SMP related fixes Atish Patra
2019-01-08  9:38 ` Atish Patra
2019-01-08  9:38 ` [PATCH v2 1/8] RISC-V: Do not wait indefinitely in __cpu_up Atish Patra
2019-01-08  9:38   ` Atish Patra
2019-01-15 13:51   ` Christoph Hellwig [this message]
2019-01-15 13:51     ` Christoph Hellwig
2019-01-18  2:35     ` Atish Patra
2019-01-18  2:35       ` Atish Patra
2019-01-18  7:20       ` Christoph Hellwig
2019-01-18  7:20         ` Christoph Hellwig
2019-01-08  9:38 ` [PATCH v2 2/8] RISC-V: Move cpuid to hartid mapping to SMP Atish Patra
2019-01-08  9:38   ` Atish Patra
2019-01-15 13:52   ` Christoph Hellwig
2019-01-15 13:52     ` Christoph Hellwig
2019-01-18  2:08     ` Atish Patra
2019-01-18  2:08       ` Atish Patra
2019-01-08  9:38 ` [PATCH v2 3/8] RISC-V: Remove NR_CPUs check during hartid search from DT Atish Patra
2019-01-08  9:38   ` Atish Patra
2019-01-08 11:48   ` Anup Patel
2019-01-08 11:48     ` Anup Patel
2019-01-15 13:52   ` Christoph Hellwig
2019-01-15 13:52     ` Christoph Hellwig
2019-01-08  9:38 ` [PATCH v2 4/8] RISC-V: Allow hartid-to-cpuid function to fail Atish Patra
2019-01-08  9:38   ` Atish Patra
2019-01-08 11:49   ` Anup Patel
2019-01-08 11:49     ` Anup Patel
2019-01-15 13:53   ` Christoph Hellwig
2019-01-15 13:53     ` Christoph Hellwig
2019-01-08  9:38 ` [PATCH v2 5/8] RISC-V: Compare cpuid with NR_CPUS before mapping Atish Patra
2019-01-08  9:38   ` Atish Patra
2019-01-08 11:49   ` Anup Patel
2019-01-08 11:49     ` Anup Patel
2019-01-15 13:53   ` Christoph Hellwig
2019-01-15 13:53     ` Christoph Hellwig
2019-01-08  9:38 ` [PATCH v2 6/8] RISC-V: Add required checks during clock source init Atish Patra
2019-01-08  9:38   ` Atish Patra
2019-01-08 11:56   ` Anup Patel
2019-01-08 11:56     ` Anup Patel
2019-01-18  2:10     ` Atish Patra
2019-01-18  2:10       ` Atish Patra
2019-01-15 13:54   ` Christoph Hellwig
2019-01-15 13:54     ` Christoph Hellwig
2019-01-08  9:38 ` [PATCH v2 7/8] RISC-V: Check and continue in case of an invalid cpuid Atish Patra
2019-01-08  9:38   ` Atish Patra
2019-01-08 11:59   ` Anup Patel
2019-01-08 11:59     ` Anup Patel
2019-01-18  2:10     ` Atish Patra
2019-01-18  2:10       ` Atish Patra
2019-01-15 13:55   ` Christoph Hellwig
2019-01-15 13:55     ` Christoph Hellwig
2019-01-08  9:38 ` [PATCH v2 8/8] RISC-V: Assign hwcap only according to current cpu Atish Patra
2019-01-08  9:38   ` Atish Patra
2019-01-08 10:33   ` Atish Patra
2019-01-08 10:33     ` Atish Patra
2019-01-08 12:01   ` Anup Patel
2019-01-08 12:01     ` Anup Patel
2019-01-15 13:56   ` Christoph Hellwig
2019-01-15 13:56     ` Christoph Hellwig
2019-01-18  2:13     ` Atish Patra
2019-01-18  2:13       ` Atish Patra

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