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    Subject[PATCH v2 21/40] tracing: Generalize per-element hist trigger data
    Date
    Up until now, hist triggers only needed per-element support for saving
    'comm' data, which was saved directly as a private data pointer.

    In anticipation of the need to save other data besides 'comm', add a
    new hist_elt_data struct for the purpose, and switch the current
    'comm'-related code over to that.

    Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
    ---
    kernel/trace/trace_events_hist.c | 65 ++++++++++++++++++++--------------------
    1 file changed, 32 insertions(+), 33 deletions(-)

    diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
    index bbca6d3..f17d394 100644
    --- a/kernel/trace/trace_events_hist.c
    +++ b/kernel/trace/trace_events_hist.c
    @@ -249,6 +249,10 @@ static u64 hist_field_timestamp(struct hist_field *hist_field, void *event,
    return ts;
    }

    +struct hist_elt_data {
    + char *comm;
    +};
    +
    static const char *hist_field_name(struct hist_field *field,
    unsigned int level)
    {
    @@ -447,26 +451,36 @@ static inline void save_comm(char *comm, struct task_struct *task)
    memcpy(comm, task->comm, TASK_COMM_LEN);
    }

    -static void hist_trigger_elt_comm_free(struct tracing_map_elt *elt)
    +static void hist_trigger_elt_data_free(struct tracing_map_elt *elt)
    {
    - kfree((char *)elt->private_data);
    + struct hist_elt_data *private_data = elt->private_data;
    +
    + kfree(private_data->comm);
    + kfree(private_data);
    }

    -static int hist_trigger_elt_comm_alloc(struct tracing_map_elt *elt)
    +static int hist_trigger_elt_data_alloc(struct tracing_map_elt *elt)
    {
    struct hist_trigger_data *hist_data = elt->map->private_data;
    + unsigned int size = TASK_COMM_LEN + 1;
    + struct hist_elt_data *elt_data;
    struct hist_field *key_field;
    unsigned int i;

    + elt->private_data = elt_data = kzalloc(sizeof(*elt_data), GFP_KERNEL);
    + if (!elt_data)
    + return -ENOMEM;
    +
    for_each_hist_key_field(i, hist_data) {
    key_field = hist_data->fields[i];

    if (key_field->flags & HIST_FIELD_FL_EXECNAME) {
    - unsigned int size = TASK_COMM_LEN + 1;
    -
    - elt->private_data = kzalloc(size, GFP_KERNEL);
    - if (!elt->private_data)
    + elt_data->comm = kzalloc(size, GFP_KERNEL);
    + if (!elt_data->comm) {
    + kfree(elt_data);
    + elt->private_data = NULL;
    return -ENOMEM;
    + }
    break;
    }
    }
    @@ -474,18 +488,18 @@ static int hist_trigger_elt_comm_alloc(struct tracing_map_elt *elt)
    return 0;
    }

    -static void hist_trigger_elt_comm_init(struct tracing_map_elt *elt)
    +static void hist_trigger_elt_data_init(struct tracing_map_elt *elt)
    {
    - char *comm = elt->private_data;
    + struct hist_elt_data *private_data = elt->private_data;

    - if (comm)
    - save_comm(comm, current);
    + if (private_data->comm)
    + save_comm(private_data->comm, current);
    }

    -static const struct tracing_map_ops hist_trigger_elt_comm_ops = {
    - .elt_alloc = hist_trigger_elt_comm_alloc,
    - .elt_free = hist_trigger_elt_comm_free,
    - .elt_init = hist_trigger_elt_comm_init,
    +static const struct tracing_map_ops hist_trigger_elt_data_ops = {
    + .elt_alloc = hist_trigger_elt_data_alloc,
    + .elt_free = hist_trigger_elt_data_free,
    + .elt_init = hist_trigger_elt_data_init,
    };

    static const char *get_hist_field_flags(struct hist_field *hist_field)
    @@ -1494,21 +1508,6 @@ static int create_tracing_map_fields(struct hist_trigger_data *hist_data)
    return 0;
    }

    -static bool need_tracing_map_ops(struct hist_trigger_data *hist_data)
    -{
    - struct hist_field *key_field;
    - unsigned int i;
    -
    - for_each_hist_key_field(i, hist_data) {
    - key_field = hist_data->fields[i];
    -
    - if (key_field->flags & HIST_FIELD_FL_EXECNAME)
    - return true;
    - }
    -
    - return false;
    -}
    -
    static struct hist_trigger_data *
    create_hist_data(unsigned int map_bits,
    struct hist_trigger_attrs *attrs,
    @@ -1534,8 +1533,7 @@ static bool need_tracing_map_ops(struct hist_trigger_data *hist_data)
    if (ret)
    goto free;

    - if (need_tracing_map_ops(hist_data))
    - map_ops = &hist_trigger_elt_comm_ops;
    + map_ops = &hist_trigger_elt_data_ops;

    hist_data->map = tracing_map_create(map_bits, hist_data->key_size,
    map_ops, hist_data);
    @@ -1724,7 +1722,8 @@ static void hist_trigger_stacktrace_print(struct seq_file *m,
    seq_printf(m, "%s: [%llx] %-55s", field_name,
    uval, str);
    } else if (key_field->flags & HIST_FIELD_FL_EXECNAME) {
    - char *comm = elt->private_data;
    + struct hist_elt_data *elt_data = elt->private_data;
    + char *comm = elt_data->comm;

    uval = *(u64 *)(key + key_field->offset);
    seq_printf(m, "%s: %-16s[%10llu]", field_name,
    --
    1.9.3
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