From: Qu Wenruo <quwenruo.btrfs@gmx.com>
To: Steven Rostedt <rostedt@goodmis.org>, Qu Wenruo <wqu@suse.com>
Cc: linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-trace-devel@vger.kernel.org
Subject: Re: [PATCH] tools/lib/traceevent, perf tools: Handle %pU format correctly
Date: Thu, 17 Oct 2019 07:46:03 +0800 [thread overview]
Message-ID: <ee81fc11-30ea-34d7-a19f-ce1811529ab4@gmx.com> (raw)
In-Reply-To: <20191016105456.0b8d2310@gandalf.local.home>
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On 2019/10/16 下午10:54, Steven Rostedt wrote:
> On Wed, 16 Oct 2019 14:39:20 +0800
> Qu Wenruo <wqu@suse.com> wrote:
>
>> +static void print_uuid_arg(struct trace_seq *s, void *data, int size,
>> + struct tep_event *event, struct tep_print_arg *arg)
>> +{
>> + const char *fmt;
>> + unsigned char *buf;
>> +
>> + fmt = "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x";
>> + if (arg->type != TEP_PRINT_FIELD) {
>> + trace_seq_printf(s, "ARG TYPE NOT FIELID but %d", arg->type);
>> + return;
>> + }
>> +
>> + if (!arg->field.field) {
>> + arg->field.field = tep_find_any_field(event, arg->field.name);
>> + if (!arg->field.field) {
>> + do_warning("%s: field %s not found",
>> + __func__, arg->field.name);
>> + return;
>> + }
>> + }
>> + buf = data + arg->field.field->offset;
>
> You also need to make sure the data field is not smaller than 16 bytes.
>
> if (arg->field.field->size < 16) {
> trace_seq_puts(s, "INVALIDUUID");
> return;
> }
>
Oh, forgot that sanity check.
>> +
>> + trace_seq_printf(s, fmt, buf[0], buf[1], buf[2], buf[3], buf[4], buf[5],
>> + buf[6], buf[7], buf[8], buf[9], buf[10], buf[11], buf[12],
>> + buf[13], buf[14], buf[15]);
>> +}
>> +
>
> Hmm, I know print_mac_addr() does something similar as this, but this
> is getting a bit extreme (too many arguments!). What about doing:
>
> for (i = 0; i < 4; i++)
> trace_seq_printf(s, "%02x", buf++);
>
> for (i = 0; i < 3; i++)
> trace_seq_printf(s, "-%02x%02x", buf[i * 2], buf[i * 2 + 1]);
>
> buf += 6;
>
> trace_seq_putc(s, '-');
>
> for (i = 0; i < 6; i++)
> trace_seq_printf(s, "%02x", buf++);
>
>
>
> Hmm, not sure the above is better, but having that many arguments just
> looks ugly to me.
Indeed, I'll update the patchset to make it more sane.
Thanks,
Qu
>
> -- Steve
>
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next prev parent reply other threads:[~2019-10-16 23:46 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-16 6:39 [PATCH] tools/lib/traceevent, perf tools: Handle %pU format correctly Qu Wenruo
2019-10-16 7:39 ` Nikolay Borisov
2019-10-16 7:44 ` Qu WenRuo
2019-10-16 14:54 ` Steven Rostedt
2019-10-16 23:46 ` Qu Wenruo [this message]
2020-01-27 15:42 Steven Rostedt
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