linux-kernel - Re: [PATCH V2 1/4] perf: Add hardware breakpoint address mask

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Date:	Tue, 23 Apr 2013 15:18:44 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Jacob Shin <jacob.shin@....com>
Cc:	Ingo Molnar <mingo@...hat.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
	Stephane Eranian <eranian@...gle.com>,
	Jiri Olsa <jolsa@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 1/4] perf: Add hardware breakpoint address mask

On 04/23, Jacob Shin wrote:
>
> +__weak int arch_validate_hwbkpt_addr_mask(struct perf_event *bp)
> +{
> +	return bp->attr.bp_addr_mask == 0;
> +}
> +
>  static int validate_hw_breakpoint(struct perf_event *bp)
>  {
>  	int ret;
> @@ -393,6 +398,10 @@ static int validate_hw_breakpoint(struct perf_event *bp)
>  	if (ret)
>  		return ret;
>  
> +	ret = arch_validate_hwbkpt_addr_mask(bp);
> +	if (ret)
> +		return ret;

Well, this looks obviously wrong?

arch_validate_hwbkpt_addr_mask() fails if bp_addr_mask == 0? and returns
"1" as the error code.

Either it should returns something like "bp_addr_mask ? -ENOTSUPP : 0"
or the caller should do "if (!validate_hw_breakpoint()) return -ERR".

Oleg.

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