Merge tag 'block-pull-request' of https://gitlab.com/stefanha/qemu into staging

Pull request

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* tag 'block-pull-request' of https://gitlab.com/stefanha/qemu:
  Rename "QEMU global mutex" to "BQL" in comments and docs
  Replace "iothread lock" with "BQL" in comments
  qemu/main-loop: rename qemu_cond_wait_iothread() to qemu_cond_wait_bql()
  qemu/main-loop: rename QEMU_IOTHREAD_LOCK_GUARD to BQL_LOCK_GUARD
  system/cpus: rename qemu_mutex_lock_iothread() to bql_lock()
  iothread: Remove unused Error** argument in aio_context_set_aio_params

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

5 files changed, 13 insertions, 14 deletions

diff --git a/docs/devel/multi-thread-tcg.rst b/docs/devel/multi-thread-tcg.rst
index c9541a7..7302c3b 100644
--- a/docs/devel/multi-thread-tcg.rst
+++ b/docs/devel/multi-thread-tcg.rst
@@ -226,10 +226,9 @@ instruction. This could be a future optimisation.
 Emulated hardware state
 -----------------------
 
-Currently thanks to KVM work any access to IO memory is automatically
-protected by the global iothread mutex, also known as the BQL (Big
-QEMU Lock). Any IO region that doesn't use global mutex is expected to
-do its own locking.
+Currently thanks to KVM work any access to IO memory is automatically protected
+by the BQL (Big QEMU Lock). Any IO region that doesn't use the BQL is expected
+to do its own locking.
 
 However IO memory isn't the only way emulated hardware state can be
 modified. Some architectures have model specific registers that
diff --git a/docs/devel/multiple-iothreads.txt b/docs/devel/multiple-iothreads.txt
index 4865196..de85767 100644
--- a/docs/devel/multiple-iothreads.txt
+++ b/docs/devel/multiple-iothreads.txt
@@ -5,7 +5,7 @@ the COPYING file in the top-level directory.
 
 
 This document explains the IOThread feature and how to write code that runs
-outside the QEMU global mutex.
+outside the BQL.
 
 The main loop and IOThreads
 ---------------------------
@@ -29,13 +29,13 @@ scalability bottleneck on hosts with many CPUs.  Work can be spread across
 several IOThreads instead of just one main loop.  When set up correctly this
 can improve I/O latency and reduce jitter seen by the guest.
 
-The main loop is also deeply associated with the QEMU global mutex, which is a
-scalability bottleneck in itself.  vCPU threads and the main loop use the QEMU
-global mutex to serialize execution of QEMU code.  This mutex is necessary
-because a lot of QEMU's code historically was not thread-safe.
+The main loop is also deeply associated with the BQL, which is a
+scalability bottleneck in itself.  vCPU threads and the main loop use the BQL
+to serialize execution of QEMU code.  This mutex is necessary because a lot of
+QEMU's code historically was not thread-safe.
 
 The fact that all I/O processing is done in a single main loop and that the
-QEMU global mutex is contended by all vCPU threads and the main loop explain
+BQL is contended by all vCPU threads and the main loop explain
 why it is desirable to place work into IOThreads.
 
 The experimental virtio-blk data-plane implementation has been benchmarked and
@@ -66,7 +66,7 @@ There are several old APIs that use the main loop AioContext:
 
 Since they implicitly work on the main loop they cannot be used in code that
 runs in an IOThread.  They might cause a crash or deadlock if called from an
-IOThread since the QEMU global mutex is not held.
+IOThread since the BQL is not held.
 
 Instead, use the AioContext functions directly (see include/block/aio.h):
  * aio_set_fd_handler() - monitor a file descriptor
diff --git a/docs/devel/qapi-code-gen.rst b/docs/devel/qapi-code-gen.rst
index 7f78183..ea82285 100644
--- a/docs/devel/qapi-code-gen.rst
+++ b/docs/devel/qapi-code-gen.rst
@@ -594,7 +594,7 @@ blocking the guest and other background operations.
 Coroutine safety can be hard to prove, similar to thread safety.  Common
 pitfalls are:
 
-- The global mutex isn't held across ``qemu_coroutine_yield()``, so
+- The BQL isn't held across ``qemu_coroutine_yield()``, so
   operations that used to assume that they execute atomically may have
   to be more careful to protect against changes in the global state.
 
diff --git a/docs/devel/replay.rst b/docs/devel/replay.rst
index 0244be8..effd856 100644
--- a/docs/devel/replay.rst
+++ b/docs/devel/replay.rst
@@ -184,7 +184,7 @@ modes.
 Reading and writing requests are created by CPU thread of QEMU. Later these
 requests proceed to block layer which creates "bottom halves". Bottom
 halves consist of callback and its parameters. They are processed when
-main loop locks the global mutex. These locks are not synchronized with
+main loop locks the BQL. These locks are not synchronized with
 replaying process because main loop also processes the events that do not
 affect the virtual machine state (like user interaction with monitor).
 
diff --git a/docs/devel/reset.rst b/docs/devel/reset.rst
index 38ed179..d4e7971 100644
--- a/docs/devel/reset.rst
+++ b/docs/devel/reset.rst
@@ -19,7 +19,7 @@ Triggering reset
 
 This section documents the APIs which "users" of a resettable object should use
 to control it. All resettable control functions must be called while holding
-the iothread lock.
+the BQL.
 
 You can apply a reset to an object using ``resettable_assert_reset()``. You need
 to call ``resettable_release_reset()`` to release the object from reset. To