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Subject[PATCH] tracing/filters: clean up filter_add_subsystem_pred()
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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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