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Block system asyncs while 'overrides_lock' is held.

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* libguile/procprop.c (scm_set_procedure_property_x): Block system
  asyncs while overrides_lock is held.  Use dynwind block in case
  an exception is thrown.
This commit is contained in:
Mark H Weaver 2013-11-17 03:19:32 -05:00
commit 8571dbde63
1 changed files with 8 additions and 2 deletions
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10
libguile/procprop.c
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@ -229,7 +229,13 @@ SCM_DEFINE (scm_set_procedure_property_x, "set-procedure-property!", 3, 0, 0,
SCM_MISC_ERROR ("arity is a deprecated read-only property", SCM_EOL);
#endif
scm_i_pthread_mutex_lock (&overrides_lock);
scm_dynwind_begin (0);
/* Here we must block asyncs while overrides_lock is held, to avoid
deadlocks which can happen as follows: scm_i_program_properties
calls out to the VM, which will run asyncs. Asyncs are permitted
to run VM code, which sometimes checks procedure properties, which
locks overrides_lock. */
scm_i_dynwind_pthread_mutex_lock_block_asyncs (&overrides_lock);
props = scm_hashq_ref (overrides, proc, SCM_BOOL_F);
if (scm_is_false (props))
{
@ -239,7 +245,7 @@ SCM_DEFINE (scm_set_procedure_property_x, "set-procedure-property!", 3, 0, 0,
props = SCM_EOL;
}
scm_hashq_set_x (overrides, proc, scm_assq_set_x (props, key, val));
scm_i_pthread_mutex_unlock (&overrides_lock);
scm_dynwind_end ();
return SCM_UNSPECIFIED;
}