linux-kernel - Re: [PATCH 1/2] perf tools: fix handling of zero-length symbols.

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Date:	Mon, 9 May 2016 14:06:31 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Chris Phlipot <cphlipot0@...il.com>
Cc:	adrian.hunter@...el.com, peterz@...radead.org, mingo@...hat.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] perf tools: fix handling of zero-length symbols.

Em Sat, May 07, 2016 at 02:16:59AM -0700, Chris Phlipot escreveu:
> This change introduces a fix to symbols__find, so that it is able to find
> symbols of length zero (where start==end)
> 
> The current code has the following problem:
> -The current implementation of symbols__find is unable to find any symbols
>  of length zero.
> -The db-export framework explicitly creates zero length symbols at
>  locations where no symbol currently exists.
> 
> The combination of the two above behaviors results in behavior similar to
> the example below.

Ok, but you made the unlikely case be the first test, how about this one
liner instead?

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 415c4f6d98fd..7a0917569fb3 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -301,7 +301,7 @@ static struct symbol *symbols__find(struct rb_root *symbols, u64 ip)
 
 		if (ip < s->start)
 			n = n->rb_left;
-		else if (ip >= s->end)
+		else if (ip > s->end || (ip == s->end && ip != s->start)
 			n = n->rb_right;
 		else
 			return s;


> +++ b/tools/perf/util/symbol.c
> @@ -299,7 +299,9 @@ static struct symbol *symbols__find(struct rb_root *symbols, u64 ip)
>  	while (n) {
>  		struct symbol *s = rb_entry(n, struct symbol, rb_node);
>  
> -		if (ip < s->start)
> +		if (ip == s->start && s->start == s->end)
> +			return s;
> +		else if (ip < s->start)
>  			n = n->rb_left;
>  		else if (ip >= s->end)
>  			n = n->rb_right;
> -- 
> 2.7.4