linux-kernel - Re: [PATCH] perf symbols: turn dso__fprintf_symbols_by

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Date:   Mon, 8 Mar 2021 11:20:48 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Yang Li <yang.lee@...ux.alibaba.com>
Cc:     peterz@...radead.org, mingo@...hat.com, mark.rutland@....com,
        alexander.shishkin@...ux.intel.com, jolsa@...hat.com,
        namhyung@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf symbols: turn dso__fprintf_symbols_by_name into
 void function

Em Mon, Mar 08, 2021 at 04:55:04PM +0800, Yang Li escreveu:
> This function always return '0' and no callers use the return value.
> So make it a void function.
> 
> Reported-by: Abaci Robot <abaci@...ux.alibaba.com>
> Signed-off-by: Yang Li <yang.lee@...ux.alibaba.com>
> ---
>  tools/perf/util/dso.h            | 2 +-
>  tools/perf/util/symbol_fprintf.c | 5 +----
>  2 files changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
> index cd2fe64..d7ebf21 100644
> --- a/tools/perf/util/dso.h
> +++ b/tools/perf/util/dso.h
> @@ -364,7 +364,7 @@ struct dso *machine__findnew_kernel(struct machine *machine, const char *name,
>  
>  void dso__reset_find_symbol_cache(struct dso *dso);
>  
> -size_t dso__fprintf_symbols_by_name(struct dso *dso, FILE *fp);
> +void dso__fprintf_symbols_by_name(struct dso *dso, FILE *fp);
>  size_t dso__fprintf(struct dso *dso, FILE *fp);
>  
>  static inline bool dso__is_vmlinux(struct dso *dso)
> diff --git a/tools/perf/util/symbol_fprintf.c b/tools/perf/util/symbol_fprintf.c
> index 35c936c..031584e 100644
> --- a/tools/perf/util/symbol_fprintf.c
> +++ b/tools/perf/util/symbol_fprintf.c
> @@ -59,10 +59,9 @@ size_t symbol__fprintf_symname(const struct symbol *sym, FILE *fp)
>  	return __symbol__fprintf_symname_offs(sym, NULL, false, false, fp);
>  }
>  
> -size_t dso__fprintf_symbols_by_name(struct dso *dso,
> +void dso__fprintf_symbols_by_name(struct dso *dso,
>  				    FILE *fp)
>  {
> -	size_t ret = 0;
>  	struct rb_node *nd;
>  	struct symbol_name_rb_node *pos;
>  
> @@ -70,6 +69,4 @@ size_t dso__fprintf_symbols_by_name(struct dso *dso,
>  		pos = rb_entry(nd, struct symbol_name_rb_node, rb_node);
>  		fprintf(fp, "%s\n", pos->sym.name);
>  	}
> -
> -	return ret;

The class__fprintf* functions follow the fprintf semantics, i.e. return
how many bytes were printed, so the fix should instead be the one below,
that I've commited to my tree, thanks for reporting!

- Arnaldo

commit 210e4c89ef61432040c6cd828fefa441f4887186
Author: Arnaldo Carvalho de Melo <acme@...hat.com>
Date:   Mon Mar 8 11:17:51 2021 -0300

    perf symbols: Fix dso__fprintf_symbols_by_name() to return the number of printed chars
    
    The 'ret' variable was initialized to zero but then it was not updated
    from the fprintf() return, fix it.
    
    Reported-by: Yang Li <yang.lee@...ux.alibaba.com>
    cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
    cc: Ingo Molnar <mingo@...hat.com>
    cc: Jiri Olsa <jolsa@...hat.com>
    cc: Mark Rutland <mark.rutland@....com>
    cc: Namhyung Kim <namhyung@...nel.org>
    Cc: Peter Zijlstra <peterz@...radead.org>
    Cc: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
    Fixes: 90f18e63fbd00513 ("perf symbols: List symbols in a dso in ascending name order")
    Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>

diff --git a/tools/perf/util/symbol_fprintf.c b/tools/perf/util/symbol_fprintf.c
index 35c936ce33efa6ea..2664fb65e47ada94 100644
--- a/tools/perf/util/symbol_fprintf.c
+++ b/tools/perf/util/symbol_fprintf.c
@@ -68,7 +68,7 @@ size_t dso__fprintf_symbols_by_name(struct dso *dso,
 
 	for (nd = rb_first_cached(&dso->symbol_names); nd; nd = rb_next(nd)) {
 		pos = rb_entry(nd, struct symbol_name_rb_node, rb_node);
-		fprintf(fp, "%s\n", pos->sym.name);
+		ret += fprintf(fp, "%s\n", pos->sym.name);
 	}
 
 	return ret;