From: Richard Henderson <richard.henderson@linaro.org>
To: qemu-devel@nongnu.org
Cc: pbonzini@redhat.com, thuth@redhat.com, ehabkost@redhat.com
Subject: [PATCH v2 6/8] include/qemu/lockable: Use _Generic instead of QEMU_GENERIC
Date: Mon, 14 Jun 2021 16:31:41 -0700 [thread overview]
Message-ID: <20210614233143.1221879-7-richard.henderson@linaro.org> (raw)
In-Reply-To: <20210614233143.1221879-1-richard.henderson@linaro.org>
This is both more and less complicated than our expansion
using __builtin_choose_expr and __builtin_types_compatible_p.
The expansion through QEMU_MAKE_LOCKABLE_ doesn't work because
we're not emumerating all of the types within the same _Generic,
which results in errors about unhandled cases. We must also
handle void* explicitly, so that the NULL constant can be used.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
include/qemu/lockable.h | 90 +++++++++++++++++++----------------------
1 file changed, 41 insertions(+), 49 deletions(-)
diff --git a/include/qemu/lockable.h b/include/qemu/lockable.h
index b620023141..86db7cb04c 100644
--- a/include/qemu/lockable.h
+++ b/include/qemu/lockable.h
@@ -24,79 +24,71 @@ struct QemuLockable {
QemuLockUnlockFunc *unlock;
};
-/* This function gives an error if an invalid, non-NULL pointer type is passed
- * to QEMU_MAKE_LOCKABLE. For optimized builds, we can rely on dead-code elimination
- * from the compiler, and give the errors already at link time.
- */
-#if defined(__OPTIMIZE__) && !defined(__SANITIZE_ADDRESS__)
-void unknown_lock_type(void *);
-#else
-static inline void unknown_lock_type(void *unused)
-{
- abort();
-}
-#endif
-
static inline __attribute__((__always_inline__)) QemuLockable *
qemu_make_lockable(void *x, QemuLockable *lockable)
{
- /* We cannot test this in a macro, otherwise we get compiler
+ /*
+ * We cannot test this in a macro, otherwise we get compiler
* warnings like "the address of 'm' will always evaluate as 'true'".
*/
return x ? lockable : NULL;
}
-/* Auxiliary macros to simplify QEMU_MAKE_LOCABLE. */
-#define QEMU_LOCK_FUNC(x) ((QemuLockUnlockFunc *) \
- QEMU_GENERIC(x, \
- (QemuMutex *, qemu_mutex_lock), \
- (QemuRecMutex *, qemu_rec_mutex_lock), \
- (CoMutex *, qemu_co_mutex_lock), \
- (QemuSpin *, qemu_spin_lock), \
- unknown_lock_type))
+static inline __attribute__((__always_inline__)) QemuLockable *
+qemu_null_lockable(void *x)
+{
+ if (x != NULL) {
+ qemu_build_not_reached();
+ }
+ return NULL;
+}
-#define QEMU_UNLOCK_FUNC(x) ((QemuLockUnlockFunc *) \
- QEMU_GENERIC(x, \
- (QemuMutex *, qemu_mutex_unlock), \
- (QemuRecMutex *, qemu_rec_mutex_unlock), \
- (CoMutex *, qemu_co_mutex_unlock), \
- (QemuSpin *, qemu_spin_unlock), \
- unknown_lock_type))
-
-/* In C, compound literals have the lifetime of an automatic variable.
+/*
+ * In C, compound literals have the lifetime of an automatic variable.
* In C++ it would be different, but then C++ wouldn't need QemuLockable
* either...
*/
-#define QEMU_MAKE_LOCKABLE_(x) (&(QemuLockable) { \
- .object = (x), \
- .lock = QEMU_LOCK_FUNC(x), \
- .unlock = QEMU_UNLOCK_FUNC(x), \
+#define QML_OBJ_(x, name) (&(QemuLockable) { \
+ .object = (x), \
+ .lock = (QemuLockUnlockFunc *) qemu_ ## name ## _lock, \
+ .unlock = (QemuLockUnlockFunc *) qemu_ ## name ## _unlock \
})
-/* QEMU_MAKE_LOCKABLE - Make a polymorphic QemuLockable
+/**
+ * QEMU_MAKE_LOCKABLE - Make a polymorphic QemuLockable
*
- * @x: a lock object (currently one of QemuMutex, QemuRecMutex, CoMutex, QemuSpin).
+ * @x: a lock object (currently one of QemuMutex, QemuRecMutex,
+ * CoMutex, QemuSpin).
*
* Returns a QemuLockable object that can be passed around
* to a function that can operate with locks of any kind, or
* NULL if @x is %NULL.
- */
-#define QEMU_MAKE_LOCKABLE(x) \
- QEMU_GENERIC(x, \
- (QemuLockable *, (x)), \
- qemu_make_lockable((x), QEMU_MAKE_LOCKABLE_(x)))
-
-/* QEMU_MAKE_LOCKABLE_NONNULL - Make a polymorphic QemuLockable
*
- * @x: a lock object (currently one of QemuMutex, QemuRecMutex, CoMutex, QemuSpin).
+ * Note the special case for void *, so that we may pass "NULL".
+ */
+#define QEMU_MAKE_LOCKABLE(x) \
+ _Generic((x), QemuLockable *: (x), \
+ void *: qemu_null_lockable(x), \
+ QemuMutex *: qemu_make_lockable(x, QML_OBJ_(x, mutex)), \
+ QemuRecMutex *: qemu_make_lockable(x, QML_OBJ_(x, rec_mutex)), \
+ CoMutex *: qemu_make_lockable(x, QML_OBJ_(x, co_mutex)), \
+ QemuSpin *: qemu_make_lockable(x, QML_OBJ_(x, spin)))
+
+/**
+ * QEMU_MAKE_LOCKABLE_NONNULL - Make a polymorphic QemuLockable
+ *
+ * @x: a lock object (currently one of QemuMutex, QemuRecMutex,
+ * 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_NONNULL(x) \
- QEMU_GENERIC(x, \
- (QemuLockable *, (x)), \
- QEMU_MAKE_LOCKABLE_(x))
+#define QEMU_MAKE_LOCKABLE_NONNULL(x) \
+ _Generic((x), QemuLockable *: (x), \
+ QemuMutex *: QML_OBJ_(x, mutex), \
+ QemuRecMutex *: QML_OBJ_(x, rec_mutex), \
+ CoMutex *: QML_OBJ_(x, co_mutex), \
+ QemuSpin *: QML_OBJ_(x, spin))
static inline void qemu_lockable_lock(QemuLockable *x)
{
--
2.25.1
next prev parent reply other threads:[~2021-06-14 23:35 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-14 23:31 [PATCH v2 0/8] configure: Change to -std=gnu11 Richard Henderson
2021-06-14 23:31 ` [PATCH v2 1/8] configure: Use -std=gnu11 Richard Henderson
2021-06-15 7:43 ` Thomas Huth
2021-06-15 10:10 ` Alex Bennée
2021-06-15 13:49 ` Philippe Mathieu-Daudé
2021-06-14 23:31 ` [PATCH v2 2/8] softfloat: Use _Generic instead of QEMU_GENERIC Richard Henderson
2021-06-15 7:48 ` Thomas Huth
2021-06-15 10:18 ` Alex Bennée
2021-06-14 23:31 ` [PATCH v2 3/8] util: Use real functions for thread-posix QemuRecMutex Richard Henderson
2021-06-15 7:50 ` Thomas Huth
2021-06-15 10:54 ` Alex Bennée
2021-06-14 23:31 ` [PATCH v2 4/8] util: Pass file+line to qemu_rec_mutex_unlock_impl Richard Henderson
2021-06-15 10:56 ` Alex Bennée
2021-06-15 13:51 ` Philippe Mathieu-Daudé
2021-06-14 23:31 ` [PATCH v2 5/8] util: Use unique type for QemuRecMutex in thread-posix.h Richard Henderson
2021-06-15 7:56 ` Thomas Huth
2021-06-15 10:57 ` Alex Bennée
2021-06-14 23:31 ` Richard Henderson [this message]
2021-06-15 11:25 ` [PATCH v2 6/8] include/qemu/lockable: Use _Generic instead of QEMU_GENERIC Alex Bennée
2021-06-14 23:31 ` [PATCH v2 7/8] qemu/compiler: Remove QEMU_GENERIC Richard Henderson
2021-06-15 11:26 ` Alex Bennée
2021-06-14 23:31 ` [PATCH v2 8/8] configure: Remove probe for _Static_assert Richard Henderson
2021-06-15 7:58 ` Thomas Huth
2021-06-15 10:29 ` Alex Bennée
2021-06-14 23:42 ` [PATCH v2 0/8] configure: Change to -std=gnu11 no-reply
2021-06-16 13:04 ` Paolo Bonzini
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210614233143.1221879-7-richard.henderson@linaro.org \
--to=richard.henderson@linaro.org \
--cc=ehabkost@redhat.com \
--cc=pbonzini@redhat.com \
--cc=qemu-devel@nongnu.org \
--cc=thuth@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).