Commit Graph

6 Commits

Author SHA1 Message Date
Daniel Brodsky 56f21718b8 lockable: fix __COUNTER__ macro to be referenced properly
- __COUNTER__ doesn't work with ## concat
- replaced ## with glue() macro so __COUNTER__ is evaluated

Fixes: 3284c3ddc4

Signed-off-by: Daniel Brodsky <dnbrdsky@gmail.com>
Message-id: 20200404042108.389635-2-dnbrdsky@gmail.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2020-05-04 16:07:43 +01:00
Stefan Hajnoczi ac90871cf8 lockable: add QemuRecMutex support
The polymorphic locking macros don't support QemuRecMutex yet.  Add it
so that lock guards can be used with QemuRecMutex.

Convert TCG plugins functions that benefit from these macros.  Manual
qemu_rec_mutex_lock/unlock() callers are left unmodified in cases where
clarity would not improve by switching to the macros.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-03-17 15:18:45 +01:00
Stefan Hajnoczi 3284c3ddc4 lockable: add lock guards
This patch introduces two lock guard macros that automatically unlock a
lock object (QemuMutex and others):

  void f(void) {
      QEMU_LOCK_GUARD(&mutex);
      if (!may_fail()) {
          return; /* automatically unlocks mutex */
      }
      ...
  }

and:

  WITH_QEMU_LOCK_GUARD(&mutex) {
      if (!may_fail()) {
          return; /* automatically unlocks mutex */
      }
  }
  /* automatically unlocks mutex here */
  ...

Convert qemu-timer.c functions that benefit from these macros as an
example.  Manual qemu_mutex_lock/unlock() callers are left unmodified in
cases where clarity would not improve by switching to the macros.

Many other QemuMutex users remain in the codebase that might benefit
from lock guards.  Over time they can be converted, if that is
desirable.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
[Use QEMU_MAKE_LOCKABLE_NONNULL. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-03-17 15:18:45 +01:00
Paolo Bonzini 8834dcf47e lockable: add QEMU_MAKE_LOCKABLE_NONNULL
This will be needed for lock guards, because if the lock is NULL the
dummy for loop of the lock guard never runs.  This can cause confusion
and dummy warnings in the compiler, but even if it did not, aborting
with a NULL pointer dereference is a less surprising behavior.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-03-17 15:18:34 +01:00
Marc-André Lureau 80818e9ecb lockable: workaround GCC link issue with ASAN
Current GCC has an optimization bug when compiling with ASAN.

See also GCC bug:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84307

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20180215212552.26997-3-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-03-06 14:01:27 +01:00
Paolo Bonzini e70372fcaf lockable: add QemuLockable
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 <pbonzini@redhat.com>
Message-Id: <20180203153935.8056-3-pbonzini@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
2018-02-08 09:22:03 +08:00