Rémi Bernon : ntdll: Stop locking heap to access block-local data.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: efc6a8f42c120beaeb747e69c38fc7914a1a40e6
URL:    https://gitlab.winehq.org/wine/wine/-/commit/efc6a8f42c120beaeb747e69c38fc79...

Author: Rémi Bernon <rbernon(a)codeweavers.com>
Date:   Mon Nov 14 15:08:40 2022 +0100

ntdll: Stop locking heap to access block-local data.

This moves unsafe_block_from_ptr calls outside of the heap lock.

We assume here that concurrent call to another heap function on a block
being freed is undefined, and it should then be safe to do so:

* The block type or base offset never change after a block has been
  allocated and until it is freed.

* Block flags such as BLOCK_FLAG_LARGE, or BLOCK_FLAG_USER_INFO also
  never change after a block has been allocated.

* Other block flags are only read and modified inside the heap lock.

---

 dlls/ntdll/heap.c | 86 +++++++++++++++++++++++++++++--------------------------
 1 file changed, 45 insertions(+), 41 deletions(-)