include: Move QemuLockCnt APIs to their own header

Currently the QemuLockCnt data structure and associated functions are
in the include/qemu/thread.h header.  Move them to their own
qemu/lockcnt.h.  The main reason for doing this is that it means we
can autogenerate the documentation comments into the docs/devel
documentation.

The copyright/author in the new header is drawn from lockcnt.c,
since the header changes were added in the same commit as
lockcnt.c; since neither thread.h nor lockcnt.c state an explicit
license, the standard default of GPL-2-or-later applies.

We include the new header (and the .c file, which was accidentally
omitted previously) in the "RCU" part of MAINTAINERS, since that
is where the lockcnt.rst documentation is categorized.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20240816132212.3602106-7-peter.maydell@linaro.org

diff --git a/MAINTAINERS b/MAINTAINERS
index bf62247872a3e032a5183d1aa8c73f78c9f8017e..c21d6a2f9e1e8879dd81226e86b56f3c02809b68 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3061,8 +3061,10 @@ S: Maintained
 F: docs/devel/lockcnt.rst
 F: docs/devel/rcu.rst
 F: include/qemu/rcu*.h
+F: include/qemu/lockcnt.h
 F: tests/unit/rcutorture.c
 F: tests/unit/test-rcu-*.c
+F: util/lockcnt.c
 F: util/rcu.c
 
 Human Monitor (HMP)

diff --git a/accel/accel-blocker.c b/accel/accel-blocker.c
index e083f24aa80747498192f19e1071949bc7b015ef..75daaa2911309515eb282c4ff2a2ea5e692f8a93 100644 (file)
--- a/accel/accel-blocker.c
+++ b/accel/accel-blocker.c
@@ -25,6 +25,7 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu/lockcnt.h"
 #include "qemu/thread.h"
 #include "qemu/main-loop.h"
 #include "hw/core/cpu.h"

diff --git a/docs/devel/lockcnt.rst b/docs/devel/lockcnt.rst
index 994aeb571510b054926c0610eb140df2db2cc542..728594bcea31eaed9e35901acf30705b566132be 100644 (file)
--- a/docs/devel/lockcnt.rst
+++ b/docs/devel/lockcnt.rst
@@ -175,7 +175,7 @@ three instructions in the critical path, two assignments and a ``smp_wmb()``.
 ``QemuLockCnt`` API
 -------------------
 
-The ``QemuLockCnt`` API is described in ``include/qemu/thread.h``.
+The ``QemuLockCnt`` API is described in ``include/qemu/lockcnt.h``.
 
 
 ``QemuLockCnt`` usage

diff --git a/hw/core/cpu-common.c b/hw/core/cpu-common.c
index 7982ecd39a534081d810fc5610557dc25cb7ca89..09c79035949b246dd29ffe15f552440e93980871 100644 (file)
--- a/hw/core/cpu-common.c
+++ b/hw/core/cpu-common.c
@@ -24,6 +24,7 @@
 #include "sysemu/hw_accel.h"
 #include "qemu/log.h"
 #include "qemu/main-loop.h"
+#include "qemu/lockcnt.h"
 #include "exec/log.h"
 #include "exec/gdbstub.h"
 #include "sysemu/tcg.h"

diff --git a/include/block/aio.h b/include/block/aio.h
index 4ee81936ed5e67e361d51168c25cefa5f1af0bb7..43883a8a33a8efcab92da58a8071ac082365ed25 100644 (file)
--- a/include/block/aio.h
+++ b/include/block/aio.h
@@ -20,6 +20,7 @@
 #include "qemu/coroutine-core.h"
 #include "qemu/queue.h"
 #include "qemu/event_notifier.h"
+#include "qemu/lockcnt.h"
 #include "qemu/thread.h"
 #include "qemu/timer.h"
 #include "block/graph-lock.h"

diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index d21a24c82fc4c65e6bd566791c170b4818b919ea..c3ca0babcb3f87ec5022506a8ca2f119c242593a 100644 (file)
--- a/include/hw/core/cpu.h
+++ b/include/hw/core/cpu.h
@@ -33,6 +33,7 @@
 #include "qemu/bitmap.h"
 #include "qemu/rcu_queue.h"
 #include "qemu/queue.h"
+#include "qemu/lockcnt.h"
 #include "qemu/thread.h"
 #include "qom/object.h"
 

diff --git a/include/qemu/lockcnt.h b/include/qemu/lockcnt.h
new file mode 100644 (file)
index 0000000..2c92ae1
--- /dev/null
+++ b/include/qemu/lockcnt.h
@@ -0,0 +1,130 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * QemuLockCnt implementation
+ *
+ * Copyright Red Hat, Inc. 2017
+ *
+ * Author:
+ *   Paolo Bonzini <pbonzini@redhat.com>
+ *
+ */
+
+#ifndef QEMU_LOCKCNT_H
+#define QEMU_LOCKCNT_H
+
+#include "qemu/thread.h"
+
+typedef struct QemuLockCnt QemuLockCnt;
+
+struct QemuLockCnt {
+#ifndef CONFIG_LINUX
+    QemuMutex mutex;
+#endif
+    unsigned count;
+};
+
+/**
+ * qemu_lockcnt_init: initialize a QemuLockcnt
+ * @lockcnt: the lockcnt to initialize
+ *
+ * Initialize lockcnt's counter to zero and prepare its mutex
+ * for usage.
+ */
+void qemu_lockcnt_init(QemuLockCnt *lockcnt);
+
+/**
+ * qemu_lockcnt_destroy: destroy a QemuLockcnt
+ * @lockcnt: the lockcnt to destruct
+ *
+ * Destroy lockcnt's mutex.
+ */
+void qemu_lockcnt_destroy(QemuLockCnt *lockcnt);
+
+/**
+ * qemu_lockcnt_inc: increment a QemuLockCnt's counter
+ * @lockcnt: the lockcnt to operate on
+ *
+ * If the lockcnt's count is zero, wait for critical sections
+ * to finish and increment lockcnt's count to 1.  If the count
+ * is not zero, just increment it.
+ *
+ * Because this function can wait on the mutex, it must not be
+ * called while the lockcnt's mutex is held by the current thread.
+ * For the same reason, qemu_lockcnt_inc can also contribute to
+ * AB-BA deadlocks.  This is a sample deadlock scenario:
+ *
+ *            thread 1                      thread 2
+ *            -------------------------------------------------------
+ *            qemu_lockcnt_lock(&lc1);
+ *                                          qemu_lockcnt_lock(&lc2);
+ *            qemu_lockcnt_inc(&lc2);
+ *                                          qemu_lockcnt_inc(&lc1);
+ */
+void qemu_lockcnt_inc(QemuLockCnt *lockcnt);
+
+/**
+ * qemu_lockcnt_dec: decrement a QemuLockCnt's counter
+ * @lockcnt: the lockcnt to operate on
+ */
+void qemu_lockcnt_dec(QemuLockCnt *lockcnt);
+
+/**
+ * qemu_lockcnt_dec_and_lock: decrement a QemuLockCnt's counter and
+ * possibly lock it.
+ * @lockcnt: the lockcnt to operate on
+ *
+ * Decrement lockcnt's count.  If the new count is zero, lock
+ * the mutex and return true.  Otherwise, return false.
+ */
+bool qemu_lockcnt_dec_and_lock(QemuLockCnt *lockcnt);
+
+/**
+ * qemu_lockcnt_dec_if_lock: possibly decrement a QemuLockCnt's counter and
+ * lock it.
+ * @lockcnt: the lockcnt to operate on
+ *
+ * If the count is 1, decrement the count to zero, lock
+ * the mutex and return true.  Otherwise, return false.
+ */
+bool qemu_lockcnt_dec_if_lock(QemuLockCnt *lockcnt);
+
+/**
+ * qemu_lockcnt_lock: lock a QemuLockCnt's mutex.
+ * @lockcnt: the lockcnt to operate on
+ *
+ * Remember that concurrent visits are not blocked unless the count is
+ * also zero.  You can use qemu_lockcnt_count to check for this inside a
+ * critical section.
+ */
+void qemu_lockcnt_lock(QemuLockCnt *lockcnt);
+
+/**
+ * qemu_lockcnt_unlock: release a QemuLockCnt's mutex.
+ * @lockcnt: the lockcnt to operate on.
+ */
+void qemu_lockcnt_unlock(QemuLockCnt *lockcnt);
+
+/**
+ * qemu_lockcnt_inc_and_unlock: combined unlock/increment on a QemuLockCnt.
+ * @lockcnt: the lockcnt to operate on.
+ *
+ * This is the same as
+ *
+ *     qemu_lockcnt_unlock(lockcnt);
+ *     qemu_lockcnt_inc(lockcnt);
+ *
+ * but more efficient.
+ */
+void qemu_lockcnt_inc_and_unlock(QemuLockCnt *lockcnt);
+
+/**
+ * qemu_lockcnt_count: query a LockCnt's count.
+ * @lockcnt: the lockcnt to query.
+ *
+ * Note that the count can change at any time.  Still, while the
+ * lockcnt is locked, one can usefully check whether the count
+ * is non-zero.
+ */
+unsigned qemu_lockcnt_count(QemuLockCnt *lockcnt);
+
+#endif

diff --git a/include/qemu/thread.h b/include/qemu/thread.h
index fb74e21c08a7662d81b36cd0f543b4f6a8d934e7..7eba27a704938ab9adb82f565768408d61ce4a64 100644 (file)
--- a/include/qemu/thread.h
+++ b/include/qemu/thread.h
@@ -293,115 +293,4 @@ static inline void qemu_spin_unlock(QemuSpin *spin)
 #endif
 }
 
-struct QemuLockCnt {
-#ifndef CONFIG_LINUX
-    QemuMutex mutex;
-#endif
-    unsigned count;
-};
-
-/**
- * qemu_lockcnt_init: initialize a QemuLockcnt
- * @lockcnt: the lockcnt to initialize
- *
- * Initialize lockcnt's counter to zero and prepare its mutex
- * for usage.
- */
-void qemu_lockcnt_init(QemuLockCnt *lockcnt);
-
-/**
- * qemu_lockcnt_destroy: destroy a QemuLockcnt
- * @lockcnt: the lockcnt to destruct
- *
- * Destroy lockcnt's mutex.
- */
-void qemu_lockcnt_destroy(QemuLockCnt *lockcnt);
-
-/**
- * qemu_lockcnt_inc: increment a QemuLockCnt's counter
- * @lockcnt: the lockcnt to operate on
- *
- * If the lockcnt's count is zero, wait for critical sections
- * to finish and increment lockcnt's count to 1.  If the count
- * is not zero, just increment it.
- *
- * Because this function can wait on the mutex, it must not be
- * called while the lockcnt's mutex is held by the current thread.
- * For the same reason, qemu_lockcnt_inc can also contribute to
- * AB-BA deadlocks.  This is a sample deadlock scenario:
- *
- *            thread 1                      thread 2
- *            -------------------------------------------------------
- *            qemu_lockcnt_lock(&lc1);
- *                                          qemu_lockcnt_lock(&lc2);
- *            qemu_lockcnt_inc(&lc2);
- *                                          qemu_lockcnt_inc(&lc1);
- */
-void qemu_lockcnt_inc(QemuLockCnt *lockcnt);
-
-/**
- * qemu_lockcnt_dec: decrement a QemuLockCnt's counter
- * @lockcnt: the lockcnt to operate on
- */
-void qemu_lockcnt_dec(QemuLockCnt *lockcnt);
-
-/**
- * qemu_lockcnt_dec_and_lock: decrement a QemuLockCnt's counter and
- * possibly lock it.
- * @lockcnt: the lockcnt to operate on
- *
- * Decrement lockcnt's count.  If the new count is zero, lock
- * the mutex and return true.  Otherwise, return false.
- */
-bool qemu_lockcnt_dec_and_lock(QemuLockCnt *lockcnt);
-
-/**
- * qemu_lockcnt_dec_if_lock: possibly decrement a QemuLockCnt's counter and
- * lock it.
- * @lockcnt: the lockcnt to operate on
- *
- * If the count is 1, decrement the count to zero, lock
- * the mutex and return true.  Otherwise, return false.
- */
-bool qemu_lockcnt_dec_if_lock(QemuLockCnt *lockcnt);
-
-/**
- * qemu_lockcnt_lock: lock a QemuLockCnt's mutex.
- * @lockcnt: the lockcnt to operate on
- *
- * Remember that concurrent visits are not blocked unless the count is
- * also zero.  You can use qemu_lockcnt_count to check for this inside a
- * critical section.
- */
-void qemu_lockcnt_lock(QemuLockCnt *lockcnt);
-
-/**
- * qemu_lockcnt_unlock: release a QemuLockCnt's mutex.
- * @lockcnt: the lockcnt to operate on.
- */
-void qemu_lockcnt_unlock(QemuLockCnt *lockcnt);
-
-/**
- * qemu_lockcnt_inc_and_unlock: combined unlock/increment on a QemuLockCnt.
- * @lockcnt: the lockcnt to operate on.
- *
- * This is the same as
- *
- *     qemu_lockcnt_unlock(lockcnt);
- *     qemu_lockcnt_inc(lockcnt);
- *
- * but more efficient.
- */
-void qemu_lockcnt_inc_and_unlock(QemuLockCnt *lockcnt);
-
-/**
- * qemu_lockcnt_count: query a LockCnt's count.
- * @lockcnt: the lockcnt to query.
- *
- * Note that the count can change at any time.  Still, while the
- * lockcnt is locked, one can usefully check whether the count
- * is non-zero.
- */
-unsigned qemu_lockcnt_count(QemuLockCnt *lockcnt);
-
 #endif

diff --git a/util/aio-posix.c b/util/aio-posix.c
index 266c9dd35fa04c91fc65345a45bd56e6fd9a78d7..06bf9f456cf97f739f916cc80a4978de3d196dcb 100644 (file)
--- a/util/aio-posix.c
+++ b/util/aio-posix.c
@@ -17,6 +17,7 @@
 #include "block/block.h"
 #include "block/thread-pool.h"
 #include "qemu/main-loop.h"
+#include "qemu/lockcnt.h"
 #include "qemu/rcu.h"
 #include "qemu/rcu_queue.h"
 #include "qemu/sockets.h"

diff --git a/util/aio-win32.c b/util/aio-win32.c
index d144f9391fb2df06eb29c5c9588671fdd13594bb..6583d5c5f31a3de12cb3ff44ae4407a3fde05737 100644 (file)
--- a/util/aio-win32.c
+++ b/util/aio-win32.c
@@ -18,6 +18,7 @@
 #include "qemu/osdep.h"
 #include "block/block.h"
 #include "qemu/main-loop.h"
+#include "qemu/lockcnt.h"
 #include "qemu/queue.h"
 #include "qemu/sockets.h"
 #include "qapi/error.h"

diff --git a/util/async.c b/util/async.c
index 3e3e4fc7126d7bae566423bd9c31d857c0ab7a7f..99db28389f66059f5691e2fb91ea1995d4b9a85b 100644 (file)
--- a/util/async.c
+++ b/util/async.c
@@ -30,6 +30,7 @@
 #include "block/graph-lock.h"
 #include "qemu/main-loop.h"
 #include "qemu/atomic.h"
+#include "qemu/lockcnt.h"
 #include "qemu/rcu_queue.h"
 #include "block/raw-aio.h"
 #include "qemu/coroutine_int.h"

diff --git a/util/fdmon-epoll.c b/util/fdmon-epoll.c
index c6413cb18fe76094214380c26b3b18c7bf2a69e9..9fb8800dde871d266ce42503c2565fe7a9e676cc 100644 (file)
--- a/util/fdmon-epoll.c
+++ b/util/fdmon-epoll.c
@@ -5,6 +5,7 @@
 
 #include "qemu/osdep.h"
 #include <sys/epoll.h>
+#include "qemu/lockcnt.h"
 #include "qemu/rcu_queue.h"
 #include "aio-posix.h"
 

diff --git a/util/lockcnt.c b/util/lockcnt.c
index 5da36946b1b6deb90621f4d64378586c6c8c2670..d07c6cc5cee49382807700179c6fe2f6cc123dec 100644 (file)
--- a/util/lockcnt.c
+++ b/util/lockcnt.c
@@ -7,6 +7,7 @@
  *   Paolo Bonzini <pbonzini@redhat.com>
  */
 #include "qemu/osdep.h"
+#include "qemu/lockcnt.h"
 #include "qemu/thread.h"
 #include "qemu/atomic.h"
 #include "trace.h"