linux-kernel - Re: [PATCH v8 03/13] perf evlist: implement control command handling functions

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Message-ID: <20200623151442.GL2619137@krava>
Date:   Tue, 23 Jun 2020 17:14:42 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Alexey Budankov <alexey.budankov@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Andi Kleen <ak@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v8 03/13] perf evlist: implement control command handling
 functions

On Tue, Jun 23, 2020 at 12:03:45PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Tue, Jun 23, 2020 at 04:56:01PM +0200, Jiri Olsa escreveu:
> > On Wed, Jun 17, 2020 at 11:36:46AM +0300, Alexey Budankov wrote:
> > 
> > SNIP
> > 
> > > +	memset(cmd_data, 0, data_size--);
> > > +
> > > +	do {
> > > +		err = read(evlist->ctl_fd.fd, &c, 1);
> > > +		if (err > 0) {
> > > +			if (c == '\n' || c == '\0')
> > > +				break;
> > > +			cmd_data[bytes_read++] = c;
> > > +			if (bytes_read == data_size)
> > > +				break;
> > > +		} else {
> > > +			if (err == -1)
> > > +				pr_err("Failed to read from ctlfd %d: %m\n", evlist->ctl_fd.fd);
> > > +			break;
> > > +		}
> > > +	} while (1);
> > > +
> > > +	pr_debug("Message from ctl_fd: \"%s%s\"\n", cmd_data,
> > > +		 bytes_read == data_size ? "" : c == '\n' ? "\\n" : "\\0");
> > > +
> > > +	if (err > 0) {
> > > +		if (!strncmp(cmd_data, EVLIST_CTL_CMD_ENABLE_TAG,
> > > +			     strlen(EVLIST_CTL_CMD_ENABLE_TAG))) {
> > 
> > you could use sizeof(EVLIST_CTL_CMD_ENABLE_TAG) instead, no function call
> 
> -1, as sizeof will get the \0, right?

yep, I think that's right

jirka

> 
> > 
> > > +			*cmd = EVLIST_CTL_CMD_ENABLE;
> > > +		} else if (!strncmp(cmd_data, EVLIST_CTL_CMD_DISABLE_TAG,
> > > +				    strlen(EVLIST_CTL_CMD_DISABLE_TAG))) {
> > 
> > ditto
> > 
> > jirka
> > 
> 
> -- 
> 
> - Arnaldo
>