[PULL,29/33] block-coroutine-wrapper: use qemu_get_current_aio_context()

Commit Message

Kevin Wolf Dec. 21, 2023, 9:23 p.m. UTC

From: Stefan Hajnoczi <[e-mail]>

Use qemu_get_current_aio_context() in mixed wrappers and coroutine
wrappers so that code runs in the caller's AioContext instead of moving
to the BlockDriverState's AioContext. This change is necessary for the
multi-queue block layer where any thread can call into the block layer.

Most wrappers are IO_CODE where it's safe to use the current AioContext
nowadays. BlockDrivers and the core block layer use their own locks and
no longer depend on the AioContext lock for thread-safety.

The bdrv_create() wrapper invokes GLOBAL_STATE code. Using the current
AioContext is safe because this code is only called with the BQL held
from the main loop thread.

Signed-off-by: Stefan Hajnoczi <[e-mail]>
Message-ID: <[e-mail]>
Reviewed-by: Eric Blake <[e-mail]>
Reviewed-by: Kevin Wolf <[e-mail]>
Signed-off-by: Kevin Wolf <[e-mail]>
---
 scripts/block-coroutine-wrapper.py | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

Patch

diff --git a/scripts/block-coroutine-wrapper.py b/scripts/block-coroutine-wrapper.py
index c9c09fcacd..dbbde99e39 100644
--- a/scripts/block-coroutine-wrapper.py
+++ b/scripts/block-coroutine-wrapper.py
@@ -92,8 +92,6 @@  def __init__(self, wrapper_type: str, return_type: str, name: str,
                                  f"{self.name}")
             self.target_name = f'{subsystem}_{subname}'
 
-        self.ctx = self.gen_ctx()
-
         self.get_result = 's->ret = '
         self.ret = 'return s.ret;'
         self.co_ret = 'return '
@@ -167,7 +165,7 @@  def create_mixed_wrapper(func: FuncDecl) -> str:
         {func.co_ret}{name}({ func.gen_list('{name}') });
     }} else {{
         {struct_name} s = {{
-            .poll_state.ctx = {func.ctx},
+            .poll_state.ctx = qemu_get_current_aio_context(),
             .poll_state.in_progress = true,
 
 { func.gen_block('            .{name} = {name},') }
@@ -191,7 +189,7 @@  def create_co_wrapper(func: FuncDecl) -> str:
 {func.return_type} {func.name}({ func.gen_list('{decl}') })
 {{
     {struct_name} s = {{
-        .poll_state.ctx = {func.ctx},
+        .poll_state.ctx = qemu_get_current_aio_context(),
         .poll_state.in_progress = true,
 
 { func.gen_block('        .{name} = {name},') }