[PATCH v2 0/2] MR882: Use atomic write for releasing threadsafe_queue spin lock.

[Jinoh Kang (＠iamahuman)]

This fixes data race in ARM/ARM64 platforms, and prevents potential
memory access reordering by the compiler.

--
  v2: msvcp90: Use atomic write for releasing threadsafe_queue spin lock.

https://gitlab.winehq.org/wine/wine/-/merge_requests/882

[PATCH v2 1/2] concrt140: Use atomic write for releasing threadsafe_queue spin lock.

[Jinoh Kang]

From: Jinoh Kang

This fixes data race in ARM/ARM64 platforms, and prevents potential
memory access reordering by the compiler.
---
 dlls/concrt140/details.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/dlls/concrt140/details.c b/dlls/concrt140/details.c
index e6711db6983..fb9e2a700eb 100644
--- a/dlls/concrt140/details.c
+++ b/dlls/concrt140/details.c
@@ -225,7 +225,7 @@ static void threadsafe_queue_push(threadsafe_queue *queue, size_t id,
         queue->tail = p;
         if(!queue->head)
             queue->head = p;
-        queue->lock = 0;
+        WriteRelease(&queue->lock, 0);
     }
     else
     {
@@ -275,7 +275,7 @@ static BOOL threadsafe_queue_pop(threadsafe_queue *queue, size_t id,
         queue->head = p->_Next;
         if(!queue->head)
             queue->tail = NULL;
-        queue->lock = 0;
+        WriteRelease(&queue->lock, 0);

/* TODO: Add exception handling */
         call__Concurrent_queue_base_v4__Deallocate_page(parent, p);

[PATCH v2 2/2] msvcp90: Use atomic write for releasing threadsafe_queue spin lock.

[Jinoh Kang]

From: Jinoh Kang

This fixes data race in ARM/ARM64 platforms, and prevents potential
memory access reordering by the compiler.
---
 dlls/msvcp90/details.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/dlls/msvcp90/details.c b/dlls/msvcp90/details.c
index 767b20b2334..8df9cbe563f 100644
--- a/dlls/msvcp90/details.c
+++ b/dlls/msvcp90/details.c
@@ -239,7 +239,7 @@ static void threadsafe_queue_push(threadsafe_queue *queue, size_t id,
         queue->tail = p;
         if(!queue->head)
             queue->head = p;
-        queue->lock = 0;
+        WriteRelease(&queue->lock, 0);
     }
     else
     {
@@ -289,7 +289,7 @@ static BOOL threadsafe_queue_pop(threadsafe_queue *queue, size_t id,
         queue->head = p->_Next;
         if(!queue->head)
             queue->tail = NULL;
-        queue->lock = 0;
+        WriteRelease(&queue->lock, 0);

/* TODO: Add exception handling */
         call__Concurrent_queue_base_v4__Deallocate_page(parent, p);

[Piotr Caban (＠piotr)]

Piotr Caban (@piotr) commented about dlls/msvcp90/details.c:
>      queue->tail = p;
>      if(!queue->head)
>          queue->head = p;
> -
>    queue->lock = 0;
> -
>    WriteRelease(&queue->lock, 0);

Isn't it better to make the `lock` member volatile?

[Jinoh Kang (＠iamahuman)]

On Mon Sep 19 08:34:24 2022 +0000, Piotr Caban wrote:
> Isn't it better to make the `lock` member volatile?

There is no guarantee that volatile accesses won't be reordered by the compiler.  We still need a barrier here.

[PATCH v2 0/2] MR882: Use atomic write for releasing threadsafe_queue spin lock. - approved

[Piotr Caban (＠piotr)]

This merge request was approved by Piotr Caban.