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X-Received-From: 2a00:1450:400c:c0c::242 Subject: [Qemu-devel] [PATCH 1/4] lockable: add QemuLockable X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: famz@redhat.com, qemu-block@nongnu.org, stefanha@redhat.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) X-ZohoMail: RDKM_2 RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" QemuLockable is a polymorphic lock type that takes an object and knows which function to use for locking and unlocking. The implementation could use C11 _Generic, but since the support is not very widespread I am instead using __builtin_choose_expr and __builtin_types_compatible_p, which are already used by include/qemu/atomic.h. QemuLockable can be used to implement lock guards, or to pass around a lock in such a way that a function can release it and re-acquire it. The next patch will do this for CoQueue. Signed-off-by: Paolo Bonzini --- include/qemu/compiler.h | 40 ++++++++++++++++++++++++++ include/qemu/coroutine.h | 4 +-- include/qemu/lockable.h | 75 ++++++++++++++++++++++++++++++++++++++++++++= ++++ include/qemu/thread.h | 5 ++-- include/qemu/typedefs.h | 4 +++ 5 files changed, 123 insertions(+), 5 deletions(-) create mode 100644 include/qemu/lockable.h diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h index 340e5fdc09..5179bedb1e 100644 --- a/include/qemu/compiler.h +++ b/include/qemu/compiler.h @@ -111,4 +111,44 @@ #define GCC_FMT_ATTR(n, m) #endif =20 +/* Implement C11 _Generic via GCC builtins. Example: + * + * QEMU_GENERIC(x, (float, sinf), (long double, sinl), sin) (x) + * + * The first argument is the discriminator. The last is the default value. + * The middle ones are tuples in "(type, expansion)" format. + */ + +/* First, find out the number of generic cases. */ +#define QEMU_GENERIC(x, ...) \ + QEMU_GENERIC_(typeof(x), __VA_ARGS__, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0) + +/* There will be extra arguments, but they are not used. */ +#define QEMU_GENERIC_(x, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9, count, ..= .) \ + QEMU_GENERIC##count(x, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9) + +/* Two more helper macros, this time to extract items from a parenthesized + * list. + */ +#define QEMU_FIRST_(a, b) a +#define QEMU_SECOND_(a, b) b + +/* ... and a final one for the common part of the "recursion". */ +#define QEMU_GENERIC_IF_(x, type_then, else_) = \ + __builtin_choose_expr(__builtin_types_compatible_p(x, = \ + QEMU_FIRST_ type_th= en), \ + QEMU_SECOND_ type_then, else_) + +/* CPP poor man's "recursion". */ +#define QEMU_GENERIC1(x, a0, ...) (a0) +#define QEMU_GENERIC2(x, a0, ...) QEMU_GENERIC_IF_(x, a0, QEMU_GENERIC1(x,= __VA_ARGS__)) +#define QEMU_GENERIC3(x, a0, ...) QEMU_GENERIC_IF_(x, a0, QEMU_GENERIC2(x,= __VA_ARGS__)) +#define QEMU_GENERIC4(x, a0, ...) QEMU_GENERIC_IF_(x, a0, QEMU_GENERIC3(x,= __VA_ARGS__)) +#define QEMU_GENERIC5(x, a0, ...) QEMU_GENERIC_IF_(x, a0, QEMU_GENERIC4(x,= __VA_ARGS__)) +#define QEMU_GENERIC6(x, a0, ...) QEMU_GENERIC_IF_(x, a0, QEMU_GENERIC5(x,= __VA_ARGS__)) +#define QEMU_GENERIC7(x, a0, ...) QEMU_GENERIC_IF_(x, a0, QEMU_GENERIC6(x,= __VA_ARGS__)) +#define QEMU_GENERIC8(x, a0, ...) QEMU_GENERIC_IF_(x, a0, QEMU_GENERIC7(x,= __VA_ARGS__)) +#define QEMU_GENERIC9(x, a0, ...) QEMU_GENERIC_IF_(x, a0, QEMU_GENERIC8(x,= __VA_ARGS__)) +#define QEMU_GENERIC10(x, a0, ...) QEMU_GENERIC_IF_(x, a0, QEMU_GENERIC9(x= , __VA_ARGS__)) + #endif /* COMPILER_H */ diff --git a/include/qemu/coroutine.h b/include/qemu/coroutine.h index ce2eb73670..8a5129741c 100644 --- a/include/qemu/coroutine.h +++ b/include/qemu/coroutine.h @@ -121,7 +121,7 @@ bool qemu_coroutine_entered(Coroutine *co); * Provides a mutex that can be used to synchronise coroutines */ struct CoWaitRecord; -typedef struct CoMutex { +struct CoMutex { /* Count of pending lockers; 0 for a free mutex, 1 for an * uncontended mutex. */ @@ -142,7 +142,7 @@ typedef struct CoMutex { unsigned handoff, sequence; =20 Coroutine *holder; -} CoMutex; +}; =20 /** * Initialises a CoMutex. This must be called before any other operation i= s used diff --git a/include/qemu/lockable.h b/include/qemu/lockable.h new file mode 100644 index 0000000000..e280431290 --- /dev/null +++ b/include/qemu/lockable.h @@ -0,0 +1,75 @@ +/* + * Polymorphic locking functions (like templates, but in C) + * + * Copyright Red Hat, Inc. 2017 + * + * Author: Paolo Bonzini + * + * This work is licensed under the terms of the GNU LGPL, version 2 or lat= er. + * See the COPYING.LIB file in the top-level directory. + * + */ + +#ifndef QEMU_LOCKABLE_H +#define QEMU_LOCKABLE_H + +#include "qemu/coroutine.h" +#include "qemu/thread.h" + +typedef void QemuLockUnlockFunc(void *); + +struct QemuLockable { + void *object; + QemuLockUnlockFunc *lock; + QemuLockUnlockFunc *unlock; +}; + +/* This function is used to give link-time errors if an invalid, non-NULL + * pointer type is passed to QEMU_MAKE_LOCKABLE. + */ +void unknown_lock_type(void *); + +/* Auxiliary macros to simplify QEMU_MAKE_LOCABLE. */ +#define QEMU_LOCK_FUNC(x) ((QemuLockUnlockFunc *) \ + QEMU_GENERIC(x, \ + (QemuMutex *, qemu_mutex_lock), \ + (CoMutex *, qemu_co_mutex_lock), \ + (QemuSpin *, qemu_spin_lock), \ + ((x) ? unknown_lock_type : NULL))) + +#define QEMU_UNLOCK_FUNC(x) ((QemuLockUnlockFunc *) \ + QEMU_GENERIC(x, \ + (QemuMutex *, qemu_mutex_unlock), \ + (CoMutex *, qemu_co_mutex_unlock), \ + (QemuSpin *, qemu_spin_unlock), \ + ((x) ? unknown_lock_type : NULL))) + +#define QEMU_MAKE_LOCKABLE_(x) (&(QemuLockable) { \ + .object =3D (x), \ + .lock =3D QEMU_LOCK_FUNC(x), \ + .unlock =3D QEMU_UNLOCK_FUNC(x), \ + }) + +/* QEMU_MAKE_LOCKABLE - Make a polymorphic QemuLockable + * + * @x: a lock object (currently one of QemuMutex, CoMutex, QemuSpin). + * + * Returns a QemuLockable object that can be passed around + * to a function that can operate with locks of any kind. + */ +#define QEMU_MAKE_LOCKABLE(x) \ + QEMU_GENERIC(x, \ + (QemuLockable *, x), \ + QEMU_MAKE_LOCKABLE_(x)) + +static inline void qemu_lockable_lock(QemuLockable *x) +{ + x->lock(x); +} + +static inline void qemu_lockable_unlock(QemuLockable *x) +{ + x->unlock(x); +} + +#endif diff --git a/include/qemu/thread.h b/include/qemu/thread.h index 9910f49b3a..a3bc056d89 100644 --- a/include/qemu/thread.h +++ b/include/qemu/thread.h @@ -4,7 +4,6 @@ #include "qemu/processor.h" #include "qemu/atomic.h" =20 -typedef struct QemuMutex QemuMutex; typedef struct QemuCond QemuCond; typedef struct QemuSemaphore QemuSemaphore; typedef struct QemuEvent QemuEvent; @@ -66,9 +65,9 @@ struct Notifier; void qemu_thread_atexit_add(struct Notifier *notifier); void qemu_thread_atexit_remove(struct Notifier *notifier); =20 -typedef struct QemuSpin { +struct QemuSpin { int value; -} QemuSpin; +}; =20 static inline void qemu_spin_init(QemuSpin *spin) { diff --git a/include/qemu/typedefs.h b/include/qemu/typedefs.h index 9bd7a834ba..5923849cdd 100644 --- a/include/qemu/typedefs.h +++ b/include/qemu/typedefs.h @@ -19,6 +19,7 @@ typedef struct BusClass BusClass; typedef struct BusState BusState; typedef struct Chardev Chardev; typedef struct CompatProperty CompatProperty; +typedef struct CoMutex CoMutex; typedef struct CPUAddressSpace CPUAddressSpace; typedef struct CPUState CPUState; typedef struct DeviceListener DeviceListener; @@ -86,9 +87,12 @@ typedef struct QEMUBH QEMUBH; typedef struct QemuConsole QemuConsole; typedef struct QemuDmaBuf QemuDmaBuf; typedef struct QEMUFile QEMUFile; +typedef struct QemuLockable QemuLockable; +typedef struct QemuMutex QemuMutex; typedef struct QemuOpt QemuOpt; typedef struct QemuOpts QemuOpts; typedef struct QemuOptsList QemuOptsList; +typedef struct QemuSpin QemuSpin; typedef struct QEMUSGList QEMUSGList; typedef struct QEMUTimer QEMUTimer; typedef struct QEMUTimerListGroup QEMUTimerListGroup; --=20 2.14.3