linux-kernel - Re: [PATCH v3 08/15] perf header: use struct feat

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Date:   Mon, 12 Jun 2017 21:18:27 -0700
From:   David Carrillo-Cisneros <davidcc@...gle.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>, Simon Que <sque@...omium.org>,
        Wang Nan <wangnan0@...wei.com>, Jiri Olsa <jolsa@...nel.org>,
        He Kuang <hekuang@...wei.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Stephane Eranian <eranian@...gle.com>,
        Paul Turner <pjt@...gle.com>
Subject: Re: [PATCH v3 08/15] perf header: use struct feat_fd to process
 header records

Good catch. The logic hasnt broken, this change is wrong. Fixed in next version.

On Thu, Jun 8, 2017 at 4:54 AM, Jiri Olsa <jolsa@...hat.com> wrote:
> On Tue, Jun 06, 2017 at 12:07:15AM -0700, David Carrillo-Cisneros wrote:
>
> SNIP
>
>> +static int process_cpu_topology(struct feat_fd *ff, void *data __maybe_unused)
>>  {
>>       u32 nr, i;
>>       char *str;
>>       struct strbuf sb;
>> -     int cpu_nr = ph->env.nr_cpus_avail;
>> +     int cpu_nr = ff->ph->env.nr_cpus_avail;
>>       u64 size = 0;
>> +     struct perf_header *ph = ff->ph;
>> +     u64 start_offset = ff->offset;
>>
>>       ph->env.cpu = calloc(cpu_nr, sizeof(*ph->env.cpu));
>>       if (!ph->env.cpu)
>>               return -1;
>>
>> -     if (do_read_u32(fd, ph, &nr))
>> +     if (do_read_u32(ff->fd, ff->ph, &nr))
>>               goto free_cpu;
>>
>>       ph->env.nr_sibling_cores = nr;
>> @@ -1764,7 +1753,7 @@ static int process_cpu_topology(struct perf_file_section *section,
>>               goto free_cpu;
>>
>>       for (i = 0; i < nr; i++) {
>> -             str = do_read_string(fd, ph);
>> +             str = do_read_string(ff->fd, ff->ph);
>>               if (!str)
>>                       goto error;
>>
>> @@ -1776,14 +1765,14 @@ static int process_cpu_topology(struct perf_file_section *section,
>>       }
>>       ph->env.sibling_cores = strbuf_detach(&sb, NULL);
>>
>> -     if (do_read_u32(fd, ph, &nr))
>> +     if (do_read_u32(ff->fd, ff->ph, &nr))
>>               return -1;
>>
>>       ph->env.nr_sibling_threads = nr;
>>       size += sizeof(u32);
>>
>>       for (i = 0; i < nr; i++) {
>> -             str = do_read_string(fd, ph);
>> +             str = do_read_string(ff->fd, ff->ph);
>>               if (!str)
>>                       goto error;
>>
>> @@ -1799,18 +1788,18 @@ static int process_cpu_topology(struct perf_file_section *section,
>>        * The header may be from old perf,
>>        * which doesn't include core id and socket id information.
>>        */
>> -     if (section->size <= size) {
>> +     if (ff->size <= ff->offset - start_offset) {
>
> I'm lost here? how is ff->offset incremented? what's 'size' good for now?
>
> thanks,
> jirka