Variables Invisible to Other Threads

NOTE(NOW_INVISIBLE_TO_OTHER_THREADS(DataExpr, ...))

NOTE(NOW_VISIBLE_TO_OTHER_THREADS(DataExpr, ...))

These annotations, which are allowed only within a function definition, tell LockLint whether or not the variables represented by the specified expressions are visible to other threads; that is, whether or not other threads could access the variables.

Another common use of these annotations is to inform LockLint that variables it would ordinarily assume are visible are in fact not visible, because no other thread has a pointer to them. This frequently occurs when allocating data off the heap--you can safely initialize the structure without holding a lock, since no other thread can yet see the structure.

Foo* p = (Foo*) malloc(sizeof(*p));
NOTE(NOW_INVISIBLE_TO_OTHER_THREADS(*p))
p->a = bar;
p->b = zot;
NOTE(NOW_VISIBLE_TO_OTHER_THREADS(*p))
add_entry(&global_foo_list, p);

Calling a function never has the side effect of making variables visible or invisible. Upon return from the function, all changes in visibility caused by the function are reversed.