Re: [PATCH V3 02/17] kallsyms, x86: Export addresses of syscall trampolines

From: Peter Zijlstra <peterz@infradead.org>
To: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Ingo Molnar <mingo@redhat.com>, Andy Lutomirski <luto@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Joerg Roedel <joro@8bytes.org>, Jiri Olsa <jolsa@redhat.com>,
	linux-kernel@vger.kernel.org, x86@kernel.org
Subject: Re: [PATCH V3 02/17] kallsyms, x86: Export addresses of syscall trampolines
Date: Wed, 6 Jun 2018 12:50:59 +0200	[thread overview]
Message-ID: <20180606105059.GF12198@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <57f1e61f-49fa-99be-6876-48775272ccec@intel.com>

On Wed, Jun 06, 2018 at 11:02:08AM +0300, Adrian Hunter wrote:
> On 05/06/18 19:00, Andi Kleen wrote:
> >> +#ifdef CONFIG_X86_64
> >> +int arch_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
> >> +		     char *name)
> >> +{
> >> +	unsigned int cpu, ncpu;
> >> +
> >> +	if (symnum >= num_possible_cpus())
> >> +		return -EINVAL;
> >> +
> >> +	for (cpu = cpumask_first(cpu_possible_mask), ncpu = 0;
> >> +	     cpu < num_possible_cpus() && ncpu < symnum;
> >> +	     cpu = cpumask_next(cpu, cpu_possible_mask), ncpu++)
> >> +		;
> > 
> > That is max_t(unsigned, cpumask_last(cpu_possible_mask), symnum)
> 
> I think it should be:
> 
> -	     cpu < num_possible_cpus() && ncpu < symnum;
> +	     ncpu < symnum;

Since we're bike-shedding:

	for_each_possible_cpu(cpu) {
		if (ncpu++ >= symnum)
			break;
	}