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Date:   Tue, 12 Feb 2019 12:19:39 +0100 (CET)
From:   Thomas Gleixner <tglx@linutronix.de>
To:     "Li, Aubrey" <aubrey.li@linux.intel.com>
cc:     Aubrey Li <aubrey.li@intel.com>, mingo@redhat.com,
        peterz@infradead.org, hpa@zytor.com, ak@linux.intel.com,
        tim.c.chen@linux.intel.com, dave.hansen@intel.com,
        arjan@linux.intel.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v9 2/3] x86,/proc/pid/status: Add AVX-512 usage elapsed
 time
In-Reply-To: <efe3e5c9-c477-8a28-5489-c943fe63efaa@linux.intel.com>
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References: <20190211185931.4386-1-aubrey.li@intel.com> <20190211185931.4386-2-aubrey.li@intel.com> <alpine.DEB.2.21.1902120905420.1654@nanos.tec.linutronix.de> <efe3e5c9-c477-8a28-5489-c943fe63efaa@linux.intel.com>
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On Tue, 12 Feb 2019, Li, Aubrey wrote:
> On 2019/2/12 16:22, Thomas Gleixner wrote:
> > On Tue, 12 Feb 2019, Aubrey Li wrote:
> >> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
> >> index d53c54b842da..60ee932070fe 100644
> >> --- a/arch/x86/include/asm/processor.h
> >> +++ b/arch/x86/include/asm/processor.h
> >> @@ -996,5 +996,7 @@ enum l1tf_mitigations {
> >>  };
> >>  
> >>  extern enum l1tf_mitigations l1tf_mitigation;
> >> +/* Add support for architecture specific output in /proc/pid/status */
> >> +extern void arch_proc_pid_status(struct seq_file *m, struct task_struct *task);
> > 
> > Sigh. This is absolutely the wrong place. The weak function is declared and
> > used in fs/proc/... So the prototype wants to be in a header which is
> > included from there independent of x86...
> 
> Can the prototype be in the architecture header if they want to call the
> function?

Basic C programming course:

 The prototype must be available before the declaration of the global
 function.

fs/proc/array.c:404:13: warning: no previous prototype for ‘arch_proc_pid_status’ [-Wmissing-prototypes]
 void __weak arch_proc_pid_status(struct seq_file *m, struct task_struct *task)

Oh well....

Thanks,

	tglx

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