Bug 58420 - Race condition of reflection.c
Summary: Race condition of reflection.c
Alias: None
Product: Runtime
Classification: Mono
Component: General ()
Version: unspecified
Hardware: PC Linux
: --- normal
Target Milestone: ---
Assignee: Bugzilla
Depends on:
Reported: 2017-07-26 21:28 UTC by Armin
Modified: 2017-07-28 17:53 UTC (History)
4 users (show)

Is this bug a regression?: ---
Last known good build:

Stack traces (22.84 KB, text/plain)
2017-07-26 21:28 UTC, Armin

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Description Armin 2017-07-26 21:28:43 UTC
Created attachment 23826 [details]
Stack traces

TSan highlighted another race that I would like to discuss - commit 5d9d139e0ac4ecbf02c70cbce5d9a0c65a43faa4 and metadata/reflection.c. Please find TSan's stack traces attached and I highlighted the affected rows with "!":

gboolean reflected_equal (gconstpointer a, gconstpointer b) {
  // ...
! return (ea->item == eb->item) && (ea->refclass == eb->refclass);

static inline MonoObjectHandle cache_object_handle (MonoDomain *domain, MonoClass *klass, gpointer item, MonoObjectHandle o) {
  // ...
  mono_domain_lock (domain);
  // ...
! e->item = item;
! e->refclass = klass;
  // ...
  mono_domain_unlock (domain);
  // ...

I am not entirely sure if there is a mechanism that prevents `reflected_equal ()` from reading a half initialised `ReflectedEntry e`.
Comment 1 Ludovic Henry 2017-07-28 17:53:48 UTC
A race shouldn't happen since we allocate and initialise the ReflectedEntry *before* inserting it into `domain->refobject_hash`.

Rodrigo, could you please confirm?