futex(2) - Linux manual page
https://man7.org/linux/man-pages/man2/futex.2.html
> Note that a wake-up can also be caused by common futex usage patterns
> in unrelated code that happened to have previously used the futex
> word's memory location (e.g., typical futex-based implementations of
> Pthreads mutexes can cause this under some conditions). Therefore,
> callers should always conservatively assume that a return value of 0
> can mean a spurious wake-up, and use the futex word's value (i.e.,
> the user-space synchronization scheme) to decide whether to continue
> to block or not.
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Link: https://lore.kernel.org/r/20250529-event-v5-1-53b285203794@daynix.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
qatomic_mb_read and qatomic_mb_set were the very first atomic primitives
introduced for QEMU; their semantics are unclear and they provide a false
sense of safety.
The last use of qatomic_mb_read() has been removed, so delete it.
qatomic_mb_set() instead can survive as an optimized
qatomic_set()+smp_mb(), similar to Linux's smp_store_mb(), but
rename it to qatomic_set_mb() to match the order of the two
operations.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Instead of using qatomic_mb_{read,set} mindlessly, just use a per-coroutine
flag that requires no synchronization.
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The remaining use of mb_read/mb_set is just to force a thread to exit
eventually. It does not order two memory accesses and therefore can be
just read/set.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The main tests directory still looks very crowded, and it's not
clear which files are part of a unit tests and which belong to
a different test subsystem. Let's clean up the mess and move the
unit tests to a separate directory.
Message-Id: <20210310063314.1049838-1-thuth@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
2021-03-12 15:46:30 +01:00
Renamed from tests/test-aio-multithread.c (Browse further)
