| Message ID | 20231129195553.942921-4-stefanha@redhat.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | aio: remove AioContext lock | expand |
On Wed, Nov 29, 2023 at 02:55:44PM -0500, Stefan Hajnoczi wrote: > aio_context_acquire()/aio_context_release() has been replaced by > fine-grained locking to protect state shared by multiple threads. The > AioContext lock still plays the role of balancing locking in > AIO_WAIT_WHILE() and many functions in QEMU either require that the > AioContext lock is held or not held for this reason. In other words, the > AioContext lock is purely there for consistency with itself and serves > no real purpose anymore. > > Stop actually acquiring/releasing the lock in > aio_context_acquire()/aio_context_release() so that subsequent patches > can remove callers across the codebase incrementally. > > I have performed "make check" and qemu-iotests stress tests across > x86-64, ppc64le, and aarch64 to confirm that there are no failures as a > result of eliminating the lock. > > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> > --- > util/async.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/util/async.c b/util/async.c > index 8f90ddc304..04ee83d220 100644 > --- a/util/async.c > +++ b/util/async.c > @@ -725,12 +725,12 @@ void aio_context_unref(AioContext *ctx) > > void aio_context_acquire(AioContext *ctx) > { > - qemu_rec_mutex_lock(&ctx->lock); > + /* TODO remove this function */ > } > > void aio_context_release(AioContext *ctx) > { > - qemu_rec_mutex_unlock(&ctx->lock); > + /* TODO remove this function */ > } > > QEMU_DEFINE_STATIC_CO_TLS(AioContext *, my_aiocontext) > -- > 2.42.0 Reviewed-by: Eric Blake <eblake@redhat.com>
Am 29.11.2023 um 20:55 hat Stefan Hajnoczi geschrieben: > aio_context_acquire()/aio_context_release() has been replaced by > fine-grained locking to protect state shared by multiple threads. The > AioContext lock still plays the role of balancing locking in > AIO_WAIT_WHILE() and many functions in QEMU either require that the > AioContext lock is held or not held for this reason. In other words, the > AioContext lock is purely there for consistency with itself and serves > no real purpose anymore. > > Stop actually acquiring/releasing the lock in > aio_context_acquire()/aio_context_release() so that subsequent patches > can remove callers across the codebase incrementally. > > I have performed "make check" and qemu-iotests stress tests across > x86-64, ppc64le, and aarch64 to confirm that there are no failures as a > result of eliminating the lock. > > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> YOLO. Acked-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/util/async.c b/util/async.c index 8f90ddc304..04ee83d220 100644 --- a/util/async.c +++ b/util/async.c @@ -725,12 +725,12 @@ void aio_context_unref(AioContext *ctx) void aio_context_acquire(AioContext *ctx) { - qemu_rec_mutex_lock(&ctx->lock); + /* TODO remove this function */ } void aio_context_release(AioContext *ctx) { - qemu_rec_mutex_unlock(&ctx->lock); + /* TODO remove this function */ } QEMU_DEFINE_STATIC_CO_TLS(AioContext *, my_aiocontext)
aio_context_acquire()/aio_context_release() has been replaced by fine-grained locking to protect state shared by multiple threads. The AioContext lock still plays the role of balancing locking in AIO_WAIT_WHILE() and many functions in QEMU either require that the AioContext lock is held or not held for this reason. In other words, the AioContext lock is purely there for consistency with itself and serves no real purpose anymore. Stop actually acquiring/releasing the lock in aio_context_acquire()/aio_context_release() so that subsequent patches can remove callers across the codebase incrementally. I have performed "make check" and qemu-iotests stress tests across x86-64, ppc64le, and aarch64 to confirm that there are no failures as a result of eliminating the lock. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> --- util/async.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)