linux-kernel - Re: [tip:perf/core] perf probe: Fix !dwarf build

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Date:	Wed, 17 Mar 2010 10:14:36 -0400
From:	Masami Hiramatsu <mhiramat@...hat.com>
To:	mingo@...hat.com, hpa@...or.com, acme@...hat.com, paulus@...ba.org,
	linux-kernel@...r.kernel.org, fweisbec@...il.com,
	a.p.zijlstra@...llo.nl, efault@....de, tglx@...utronix.de,
	mhiramat@...hat.com, mingo@...e.hu
CC:	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:perf/core] perf probe: Fix !dwarf build

Oops, thank you,

Acked-by: Masami Hiramatsu <mhiramat@...hat.com>

tip-bot for Ingo Molnar wrote:
> Commit-ID:  3b0d516463f8deb897a55cb81e9dbbe58a2490ed
> Gitweb:     http://git.kernel.org/tip/3b0d516463f8deb897a55cb81e9dbbe58a2490ed
> Author:     Ingo Molnar <mingo@...e.hu>
> AuthorDate: Wed, 17 Mar 2010 12:13:28 +0100
> Committer:  Ingo Molnar <mingo@...e.hu>
> CommitDate: Wed, 17 Mar 2010 12:13:28 +0100
> 
> perf probe: Fix !dwarf build
> 
> Fix the !drawf build.
> 
> This uses the existing NO_DWARF_SUPPORT mechanism we use for that,
> but it's really fragile and needs a cleanup. (in a separate patch)
> 
> 1) Such uses:
> 
>  #ifndef NO_DWARF_SUPPORT
> 
> are double inverted logic a'la 'not not'. Instead the flag should
> be called DWARF_SUPPORT.
> 
> 2) Furthermore, assymetric #ifdef polluted code flow like:
> 
>         if (need_dwarf)
>  #ifdef NO_DWARF_SUPPORT
>                 die("Debuginfo-analysis is not supported");
>  #else   /* !NO_DWARF_SUPPORT */
>                 pr_debug("Some probes require debuginfo.\n");
> 
>         fd = open_vmlinux();
> 
> is very fragile and not acceptable. Instead of that helper functions
> should be created and the dwarf/no-dwarf logic should be separated more
> cleanly.
> 
> 3) Local variable #ifdefs like this:
> 
>  #ifndef NO_DWARF_SUPPORT
>         int fd;
>  #endif
> 
> Are fragile as well and should be eliminated. Helper functions achieve
> that too.
> 
> Cc: Masami Hiramatsu <mhiramat@...hat.com>
> Cc: Frederic Weisbecker <fweisbec@...il.com>
> Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
> Cc: Paul Mackerras <paulus@...ba.org>
> Cc: Mike Galbraith <efault@....de>
> Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> LKML-Reference: <20100316220612.32050.33806.stgit@...alhost6.localdomain6>
> Signed-off-by: Ingo Molnar <mingo@...e.hu>
> ---
>  tools/perf/util/probe-event.c |    6 ++++++
>  1 files changed, 6 insertions(+), 0 deletions(-)
> 
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index 64dea6c..f333269 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -1012,8 +1012,10 @@ end_dwarf:
>  	if (!sym)
>  		die("Kernel symbol \'%s\' not found - probe not added.",
>  		    tev->point.symbol);
> +#ifndef NO_DWARF_SUPPORT
>  found:
>  	close(fd);
> +#endif
>  	return ntevs;
>  }
>  
> @@ -1172,10 +1174,13 @@ void show_line_range(struct line_range *lr)
>  	unsigned int l = 1;
>  	struct line_node *ln;
>  	FILE *fp;
> +#ifndef NO_DWARF_SUPPORT
>  	int fd, ret;
> +#endif
>  
>  	/* Search a line range */
>  	init_vmlinux();
> +#ifndef NO_DWARF_SUPPORT
>  	fd = open_vmlinux();
>  	if (fd < 0)
>  		die("Could not open debuginfo file.");
> @@ -1183,6 +1188,7 @@ void show_line_range(struct line_range *lr)
>  	if (ret <= 0)
>  		die("Source line is not found.\n");
>  	close(fd);
> +#endif
>  
>  	setup_pager();
>  

-- 
Masami Hiramatsu
e-mail: mhiramat@...hat.com

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