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    SubjectRe: [PATCH v2 02/14] perf mem: Introduce weak function perf_mem_events__ptr()
    On Fri, Sep 04, 2020 at 08:34:47AM +0800, Leo Yan wrote:
    > Hi Jiri,
    >
    > On Thu, Sep 03, 2020 at 03:50:54PM +0200, Jiri Olsa wrote:
    > > On Tue, Sep 01, 2020 at 09:38:03AM +0100, Leo Yan wrote:
    > >
    > > SNIP
    > >
    > > > @@ -2941,30 +2942,38 @@ static int perf_c2c__record(int argc, const char **argv)
    > > > rec_argv[i++] = "record";
    > > >
    > > > if (!event_set) {
    > > > - perf_mem_events[PERF_MEM_EVENTS__LOAD].record = true;
    > > > - perf_mem_events[PERF_MEM_EVENTS__STORE].record = true;
    > > > + e = perf_mem_events__ptr(PERF_MEM_EVENTS__LOAD);
    > > > + e->record = true;
    > > > +
    > > > + e = perf_mem_events__ptr(PERF_MEM_EVENTS__STORE);
    > > > + e->record = true;
    > > > }
    > > >
    > > > - if (perf_mem_events[PERF_MEM_EVENTS__LOAD].record)
    > > > + e = perf_mem_events__ptr(PERF_MEM_EVENTS__LOAD);
    > > > + if (e->record)
    > > > rec_argv[i++] = "-W";
    > > >
    > > > rec_argv[i++] = "-d";
    > > > rec_argv[i++] = "--phys-data";
    > > > rec_argv[i++] = "--sample-cpu";
    > > >
    > > > - for (j = 0; j < PERF_MEM_EVENTS__MAX; j++) {
    > > > - if (!perf_mem_events[j].record)
    > > > + j = 0;
    > > > + while ((e = perf_mem_events__ptr(j)) != NULL) {
    > > > + if (!e->record) {
    > >
    > > you could keep the above 'for loop' in here, it seems better
    > > than taking care of j++
    >
    > Actually in patch v1 I did this way :) I followed James' suggestion to
    > encapsulate PERF_MEM_EVENTS__MAX into perf_mem_events__ptr(), thus
    > builtin-mem.c and buildin-c2c.c are not necessary to use
    > PERF_MEM_EVENTS__MAX in the loop and only needs to detect if the
    > pointer is NULL or not when return from perf_mem_events__ptr().

    ah because u added that load_store event

    >
    > How about change as below?
    >
    > for (j = 0; (e = perf_mem_events__ptr(j)) != NULL; j++) {
    > [...]

    will this work? e will be NULL for first iteration no?

    there are still other for loops with PERF_MEM_EVENTS__MAX used
    in the patch.. you overload the perf_mem_events access for arm,
    and add missing load_store NULL item to generic version, so there's
    always PERF_MEM_EVENTS__MAX items in the array

    can we just use the current for loop and check for e->tag != NULL
    or any other field

    thanks,
    jirka

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