Re: [PATCH v10 04/21] aio-wait.h: introduce AIO_WAIT_WHILE_UNLOCKED

[Kevin Wolf]

Am 25.07.2022 um 09:38 hat Emanuele Giuseppe Esposito geschrieben:
> Same as AIO_WAIT_WHILE macro, but if we are in the Main loop
> do not release and then acquire ctx_ 's aiocontext.
> 
> Once all Aiocontext locks go away, this macro will replace
> AIO_WAIT_WHILE.
> 
> Signed-off-by: Emanuele Giuseppe Esposito 
> Reviewed-by: Stefan Hajnoczi 
> Reviewed-by: Vladimir Sementsov-Ogievskiy 
> ---
>  include/block/aio-wait.h | 17 +
>  1 file changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/include/block/aio-wait.h b/include/block/aio-wait.h
> index 54840f8622..a61f82c617 100644
> --- a/include/block/aio-wait.h
> +++ b/include/block/aio-wait.h
> @@ -59,10 +59,13 @@ typedef struct {
>  extern AioWait global_aio_wait;
>  
>  /**
> - * AIO_WAIT_WHILE:
> + * _AIO_WAIT_WHILE:
>   * @ctx: the aio context, or NULL if multiple aio contexts (for which the
>   *   caller does not hold a lock) are involved in the polling condition.
>   * @cond: wait while this conditional expression is true
> + * @unlock: whether to unlock and then lock again @ctx. This apples
> + * only when waiting for another AioContext from the main loop.
> + * Otherwise it's ignored.
>   *
>   * Wait while a condition is true.  Use this to implement synchronous
>   * operations that require event loop activity.
> @@ -75,7 +78,7 @@ extern AioWait global_aio_wait;
>   * wait on conditions between two IOThreads since that could lead to 
> deadlock,
>   * go via the main loop instead.
>   */
> -#define AIO_WAIT_WHILE(ctx, cond) ({   \
> +#define _AIO_WAIT_WHILE(ctx, cond, unlock) ({  \

"All identifiers that begin with an underscore and either an uppercase
letter or another underscore are always reserved for any use." (C11,
7.1.3)

Kevin

[PATCH v10 04/21] aio-wait.h: introduce AIO_WAIT_WHILE_UNLOCKED

[Emanuele Giuseppe Esposito]

Same as AIO_WAIT_WHILE macro, but if we are in the Main loop
do not release and then acquire ctx_ 's aiocontext.

Once all Aiocontext locks go away, this macro will replace
AIO_WAIT_WHILE.

Signed-off-by: Emanuele Giuseppe Esposito 
Reviewed-by: Stefan Hajnoczi 
Reviewed-by: Vladimir Sementsov-Ogievskiy 
---
 include/block/aio-wait.h | 17 +
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/include/block/aio-wait.h b/include/block/aio-wait.h
index 54840f8622..a61f82c617 100644
--- a/include/block/aio-wait.h
+++ b/include/block/aio-wait.h
@@ -59,10 +59,13 @@ typedef struct {
 extern AioWait global_aio_wait;
 
 /**
- * AIO_WAIT_WHILE:
+ * _AIO_WAIT_WHILE:
  * @ctx: the aio context, or NULL if multiple aio contexts (for which the
  *   caller does not hold a lock) are involved in the polling condition.
  * @cond: wait while this conditional expression is true
+ * @unlock: whether to unlock and then lock again @ctx. This apples
+ * only when waiting for another AioContext from the main loop.
+ * Otherwise it's ignored.
  *
  * Wait while a condition is true.  Use this to implement synchronous
  * operations that require event loop activity.
@@ -75,7 +78,7 @@ extern AioWait global_aio_wait;
  * wait on conditions between two IOThreads since that could lead to deadlock,
  * go via the main loop instead.
  */
-#define AIO_WAIT_WHILE(ctx, cond) ({   \
+#define _AIO_WAIT_WHILE(ctx, cond, unlock) ({  \
 bool waited_ = false;  \
 AioWait *wait_ = _aio_wait; \
 AioContext *ctx_ = (ctx);  \
@@ -92,11 +95,11 @@ extern AioWait global_aio_wait;
 assert(qemu_get_current_aio_context() ==   \
qemu_get_aio_context());\
 while ((cond)) {   \
-if (ctx_) {\
+if (unlock && ctx_) {  \
 aio_context_release(ctx_); \
 }  \
 aio_poll(qemu_get_aio_context(), true);\
-if (ctx_) {\
+if (unlock && ctx_) {  \
 aio_context_acquire(ctx_); \
 }  \
 waited_ = true;\
@@ -105,6 +108,12 @@ extern AioWait global_aio_wait;
 qatomic_dec(_->num_waiters);  \
 waited_; })
 
+#define AIO_WAIT_WHILE(ctx, cond)  \
+_AIO_WAIT_WHILE(ctx, cond, true)
+
+#define AIO_WAIT_WHILE_UNLOCKED(ctx, cond) \
+_AIO_WAIT_WHILE(ctx, cond, false)
+
 /**
  * aio_wait_kick:
  * Wake up the main thread if it is waiting on AIO_WAIT_WHILE().  During
-- 
2.31.1