Messages in this thread | | | From | Alexei Starovoitov <> | Date | Sat, 4 Apr 2015 08:36:44 -0700 | Subject | Re: [PATCH v3 5/7] tracing: Add 'hist' event trigger command |
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On Fri, Apr 3, 2015 at 8:51 AM, Tom Zanussi <tom.zanussi@linux.intel.com> wrote: > +static struct hist_trigger_entry * > +tracing_map_insert(struct tracing_map *map, void *key) > +{ > + u32 idx, key_hash, test_key; > + > + key_hash = jhash(key, map->key_size, 0); > + idx = key_hash >> (32 - (map->map_bits + 1)); > + > + while (1) { > + idx &= (map->map_size - 1); > + test_key = map->map[idx].key; > + > + if (test_key && test_key == key_hash && > + keys_match(key, map->map[idx].val->key, map->key_size)) > + return map->map[idx].val; > + > + if (!test_key && !cmpxchg(&map->map[idx].key, 0, key_hash)) { > + struct hist_trigger_entry *entry; > + > + entry = hist_trigger_entry_create(map); > + if (!entry) > + break; > + memcpy(entry->key, key, map->key_size); > + map->map[idx].val = entry; > + > + return map->map[idx].val; > + }
There is obvious race here, since algorithm is not implemented correctly. Partially inserted key/value is not handled.
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