Userspace heap allocator is not thread safe

[Jakub Jermář]

The userspace heap allocator is not thread safe. At least I can't see any protection of the heap state variables such as heap_pages and heap_end.

[Martin Decky]

The observation that the heap allocator is not thread safe is completely correct. However, I am not sure whether the standard malloc() and free() functions are defined to be thread safe by the C specification.

There are two basic solutions:

• Keep malloc() and free() as they are and introduce a new thread safe API based on them.
• Make malloc() and free() thread safe by themselves, possibly deviating slightly from common practice (but anyway it is not a major deviation).

[Martin Decky]

The academical dilemma was solved by brute force. As of changeset head,370 malloc() and free() are thread-safe by default.