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    Subject[PATCH] tracing/filters: clean up filter_add_subsystem_pred()
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    Date
    This patch cleans up filter_add_subsystem_pred():

    - searches for the field before creating a copy of the pred
    - fixes memory leak in the case a predicate isn't applied
    - if -ENOMEM, makes sure there's no longer a reference to the pred so
    the caller can free the half-finished filter
    - changes the confusing i == MAX_FILTER_PRED - 1 comparison previously
    remarked upon

    This affects only per-subsystem event filtering.

    Signed-off-by: Tom Zanussi <tzanussi@gmail.com>

    ---
    kernel/trace/trace_events.c | 1 +
    kernel/trace/trace_events_filter.c | 31 ++++++++++++++++++++++++-------
    2 files changed, 25 insertions(+), 7 deletions(-)

    diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
    index 594d78a..ee5e51f 100644
    --- a/kernel/trace/trace_events.c
    +++ b/kernel/trace/trace_events.c
    @@ -585,6 +585,7 @@ subsystem_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
    }

    if (filter_add_subsystem_pred(system, pred)) {
    + filter_free_subsystem_preds(system);
    filter_free_pred(pred);
    return -EINVAL;
    }
    diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
    index fd01d80..4117c2e 100644
    --- a/kernel/trace/trace_events_filter.c
    +++ b/kernel/trace/trace_events_filter.c
    @@ -318,22 +318,39 @@ int filter_add_subsystem_pred(struct event_subsystem *system,
    system->preds[i] = pred;
    break;
    }
    - if (i == MAX_FILTER_PRED - 1)
    - return -EINVAL;
    }

    + if (i == MAX_FILTER_PRED)
    + return -EINVAL;
    +
    events_for_each(call) {
    + int err;
    +
    if (!call->name || !call->regfunc)
    continue;

    - if (!strcmp(call->system, system->name)) {
    - event_pred = copy_pred(pred);
    - if (event_pred)
    - filter_add_pred(call, event_pred);
    - }
    + if (strcmp(call->system, system->name))
    + continue;
    +
    + if (!find_event_field(call, pred->field_name))
    + continue;
    +
    + event_pred = copy_pred(pred);
    + if (!event_pred)
    + goto oom;
    +
    + err = filter_add_pred(call, event_pred);
    + if (err)
    + filter_free_pred(event_pred);
    + if (err == -ENOMEM)
    + goto oom;
    }

    return 0;
    +
    +oom:
    + system->preds[i] = NULL;
    + return -ENOMEM;
    }

    int filter_parse(char **pbuf, struct filter_pred *pred)
    --
    1.5.6.3




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