Blame SOURCES/kvm-aio-wait-Increase-num_waiters-even-in-home-thread.patch

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From 6d0923cbc54fc8eb983f433ca34a09e2a9982035 Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Wed, 10 Oct 2018 20:21:57 +0100
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Subject: [PATCH 31/49] aio-wait: Increase num_waiters even in home thread
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <20181010202213.7372-19-kwolf@redhat.com>
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Patchwork-id: 82609
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O-Subject: [RHEL-8 qemu-kvm PATCH 28/44] aio-wait: Increase num_waiters even in home thread
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Bugzilla: 1637976
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RH-Acked-by: Max Reitz <mreitz@redhat.com>
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RH-Acked-by: John Snow <jsnow@redhat.com>
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RH-Acked-by: Thomas Huth <thuth@redhat.com>
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Even if AIO_WAIT_WHILE() is called in the home context of the
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AioContext, we still want to allow the condition to change depending on
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other threads as long as they kick the AioWait. Specfically block jobs
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can be running in an I/O thread and should then be able to kick a drain
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in the main loop context.
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Reviewed-by: Fam Zheng <famz@redhat.com>
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(cherry picked from commit 486574483aba988c83b20e7d3f1ccd50c4c333d8)
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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 include/block/aio-wait.h | 6 +++---
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 1 file changed, 3 insertions(+), 3 deletions(-)
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diff --git a/include/block/aio-wait.h b/include/block/aio-wait.h
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index c85a62f..600fad1 100644
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--- a/include/block/aio-wait.h
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+++ b/include/block/aio-wait.h
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@@ -76,6 +76,8 @@ typedef struct {
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     bool waited_ = false;                                          \
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     AioWait *wait_ = (wait);                                       \
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     AioContext *ctx_ = (ctx);                                      \
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+    /* Increment wait_->num_waiters before evaluating cond. */     \
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+    atomic_inc(&wait_->num_waiters);                               \
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     if (ctx_ && in_aio_context_home_thread(ctx_)) {                \
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         while ((cond)) {                                           \
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             aio_poll(ctx_, true);                                  \
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@@ -84,8 +86,6 @@ typedef struct {
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     } else {                                                       \
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         assert(qemu_get_current_aio_context() ==                   \
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                qemu_get_aio_context());                            \
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-        /* Increment wait_->num_waiters before evaluating cond. */ \
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-        atomic_inc(&wait_->num_waiters);                           \
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         while ((cond)) {                                           \
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             if (ctx_) {                                            \
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                 aio_context_release(ctx_);                         \
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@@ -96,8 +96,8 @@ typedef struct {
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             }                                                      \
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             waited_ = true;                                        \
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         }                                                          \
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-        atomic_dec(&wait_->num_waiters);                           \
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     }                                                              \
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+    atomic_dec(&wait_->num_waiters);                               \
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     waited_; })
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 /**
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-- 
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1.8.3.1
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