linux-kernel - Re: [PATCH 05/24] perf daemon: Add client socket support

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Date:   Thu, 11 Feb 2021 17:35:04 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...nel.org>, lkml <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Ingo Molnar <mingo@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Michael Petlan <mpetlan@...hat.com>,
        Ian Rogers <irogers@...gle.com>,
        Alexei Budankov <abudankov@...wei.com>
Subject: Re: [PATCH 05/24] perf daemon: Add client socket support

On Thu, Feb 11, 2021 at 09:52:05AM -0300, Arnaldo Carvalho de Melo wrote:
> Em Mon, Feb 08, 2021 at 09:08:49PM +0100, Jiri Olsa escreveu:
> > +__maybe_unused
> > +static int send_cmd(struct daemon *daemon, union cmd *cmd)
> > +{
> > +	int ret = -1, fd;
> > +	char *line = NULL;
> > +	size_t len = 0;
> > +	ssize_t nread;
> > +	FILE *in = NULL;
> > +
> > +	if (setup_client_config(daemon))
> > +		return -1;
> > +
> > +	fd = setup_client_socket(daemon);
> > +	if (fd < 0)
> > +		return -1;
> > +
> > +	if (sizeof(*cmd) != writen(fd, cmd, sizeof(*cmd))) {
> > +		perror("failed: write");
> > +		goto out;
> > +	}
> > +
> > +	in = fdopen(fd, "r");
> > +	if (!in) {
> > +		perror("failed: fdopen");
> > +		goto out;
> > +	}
> > +
> > +	while ((nread = getline(&line, &len, in)) != -1) {
> > +		fwrite(line, nread, 1, stdout);
> > +		fflush(stdout);
> > +	}
> > +
> > +	ret = 0;
> > +	fclose(in);
> > +out:
> > +	/* If in is defined, then fd is closed via fclose. */
> > +	if (!in)
> > +		close(fd);
> > +	return ret;
> > +}
> > +
> 
> So I had to add the patch below to deal with this in some systems:
> 
>   cc1: warnings being treated as errors
>   builtin-daemon.c: In function 'send_cmd':  MKDIR    /tmp/build/perf/bench/
>   
>   builtin-daemon.c:1368: error: ignoring return value of 'fwrite', declared with attribute warn_unused_result
>     MKDIR    /tmp/build/perf/tests/
>   make[3]: *** [/tmp/build/perf/builtin-daemon.o] Error 1
> 
> And also to not leak the 'line' buffer allocated by getline(), since you
> initialized line to NULL and len to zero, man page says:
> 
> 	 If *lineptr is set to NULL and *n is set 0 before the call,
> 	 then getline() will allocate a buffer for storing the line.
> 	 This buffer should be freed by the user program even if
> 	 getline() failed.
> 
> 
> diff --git a/tools/perf/builtin-daemon.c b/tools/perf/builtin-daemon.c
> index e0880c5ee39c89bd..0a282c4e23a9fd9a 100644
> --- a/tools/perf/builtin-daemon.c
> +++ b/tools/perf/builtin-daemon.c
> @@ -344,12 +344,15 @@ static int send_cmd(struct daemon *daemon, union cmd *cmd)
>  	}
>  
>  	while ((nread = getline(&line, &len, in)) != -1) {
> -		fwrite(line, nread, 1, stdout);
> +		if (fwrite(line, nread, 1, stdout) != 1)
> +			goto out_fclose;
>  		fflush(stdout);
>  	}
>  
>  	ret = 0;
> +out_fclose:
>  	fclose(in);
> +	free(line);
>  out:
>  	/* If in is defined, then fd is closed via fclose. */
>  	if (!in)
> 

ok, thanks

jirka