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From 6d0923cbc54fc8eb983f433ca34a09e2a9982035 Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Wed, 10 Oct 2018 20:21:57 +0100
Subject: [PATCH 31/49] aio-wait: Increase num_waiters even in home thread

RH-Author: Kevin Wolf <kwolf@redhat.com>
Message-id: <20181010202213.7372-19-kwolf@redhat.com>
Patchwork-id: 82609
O-Subject: [RHEL-8 qemu-kvm PATCH 28/44] aio-wait: Increase num_waiters even in home thread
Bugzilla: 1637976
RH-Acked-by: Max Reitz <mreitz@redhat.com>
RH-Acked-by: John Snow <jsnow@redhat.com>
RH-Acked-by: Thomas Huth <thuth@redhat.com>

Even if AIO_WAIT_WHILE() is called in the home context of the
AioContext, we still want to allow the condition to change depending on
other threads as long as they kick the AioWait. Specfically block jobs
can be running in an I/O thread and should then be able to kick a drain
in the main loop context.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
(cherry picked from commit 486574483aba988c83b20e7d3f1ccd50c4c333d8)
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
---
 include/block/aio-wait.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/block/aio-wait.h b/include/block/aio-wait.h
index c85a62f..600fad1 100644
--- a/include/block/aio-wait.h
+++ b/include/block/aio-wait.h
@@ -76,6 +76,8 @@ typedef struct {
     bool waited_ = false;                                          \
     AioWait *wait_ = (wait);                                       \
     AioContext *ctx_ = (ctx);                                      \
+    /* Increment wait_->num_waiters before evaluating cond. */     \
+    atomic_inc(&wait_->num_waiters);                               \
     if (ctx_ && in_aio_context_home_thread(ctx_)) {                \
         while ((cond)) {                                           \
             aio_poll(ctx_, true);                                  \
@@ -84,8 +86,6 @@ typedef struct {
     } else {                                                       \
         assert(qemu_get_current_aio_context() ==                   \
                qemu_get_aio_context());                            \
-        /* Increment wait_->num_waiters before evaluating cond. */ \
-        atomic_inc(&wait_->num_waiters);                           \
         while ((cond)) {                                           \
             if (ctx_) {                                            \
                 aio_context_release(ctx_);                         \
@@ -96,8 +96,8 @@ typedef struct {
             }                                                      \
             waited_ = true;                                        \
         }                                                          \
-        atomic_dec(&wait_->num_waiters);                           \
     }                                                              \
+    atomic_dec(&wait_->num_waiters);                               \
     waited_; })
 
 /**
-- 
1.8.3.1