linux-kernel - Re: [PATCH v6] perf: __kmod_path__parse: deal with kernel module names in '[]' correctly.

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Date:	Thu, 28 May 2015 10:33:48 +0200
From:	Jiri Olsa <jolsa@...hat.com>
To:	Wang Nan <wangnan0@...wei.com>
Cc:	acme@...nel.org, jolsa@...nel.org, mingo@...hat.com,
	namhyung@...nel.org, lizefan@...wei.com, pi3orama@....com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6] perf: __kmod_path__parse: deal with kernel module
 names in '[]' correctly.

On Tue, Apr 21, 2015 at 03:33:10AM +0000, Wang Nan wrote:
> Before patch ba92732e9808df679ddf75c5ea1c0caae6d7dce2 ('perf kmaps:
> Check kmaps to make code more robust'), perf report and perf annotate
> will segfault if trace data contains kernel module information like
> this:

sry I've lost track on this one.. found it under:
  [PATCH v4 2/2] perf: report/annotate: fix segfault problem.

my comments were addressed and other than one nit below
it looks ok to me

Namhyung, I looked up in history that you had question on this one,
could you please recheck Wang's reply?

thanks,
jirka


SNIP

> diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
> index fc0ddd5..e9d4ae4 100644
> --- a/tools/perf/util/dso.c
> +++ b/tools/perf/util/dso.c
> @@ -165,13 +165,25 @@ bool is_supported_compression(const char *ext)
>  	return false;
>  }
>  
> -bool is_kernel_module(const char *pathname)
> +bool is_kernel_module(const char *pathname, int cpumode)
>  {
>  	struct kmod_path m;
>  
> -	if (kmod_path__parse(&m, pathname))
> -		return NULL;
> +	/* caller should pass a masked cpumode. Mask again for safety. */
> +	switch (cpumode & PERF_RECORD_MISC_CPUMODE_MASK) {

I think it's better to print out if there's unexpected error as
warning rather than hide it.. like we do with WARN_ONCE
or pr_warning stuff


> +	case PERF_RECORD_MISC_USER:
> +	case PERF_RECORD_MISC_HYPERVISOR:
> +	case PERF_RECORD_MISC_GUEST_USER:
> +		return false;
> +	/* Regard PERF_RECORD_MISC_CPUMODE_UNKNOWN as kernel */
> +	default:
> +		if (kmod_path__parse(&m, pathname)) {
> +			pr_err("Failed to check whether %s is a kernel module or not. Assume it is.",
> +					pathname);
>  
> +			return true;
> +		}
> +	}
>  	return m.kmod;

SNIP
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