From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48540) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YOqPu-0004e2-Dj for qemu-devel@nongnu.org; Fri, 20 Feb 2015 11:27:03 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YOqPs-00065c-W1 for qemu-devel@nongnu.org; Fri, 20 Feb 2015 11:27:02 -0500 Received: from mx1.redhat.com ([209.132.183.28]:47149) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YOqPs-00065O-PS for qemu-devel@nongnu.org; Fri, 20 Feb 2015 11:27:00 -0500 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id t1KGR0BQ014519 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Fri, 20 Feb 2015 11:27:00 -0500 From: Paolo Bonzini Date: Fri, 20 Feb 2015 17:26:51 +0100 Message-Id: <1424449612-18215-3-git-send-email-pbonzini@redhat.com> In-Reply-To: <1424449612-18215-1-git-send-email-pbonzini@redhat.com> References: <1424449612-18215-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PATCH 2/3] AioContext: acquire/release AioContext during aio_poll List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: famz@redhat.com, stefanha@redhat.com This is the first step in pushing down acquire/release, and will let rfifolock drop the contention callback feature. Signed-off-by: Paolo Bonzini --- aio-posix.c | 9 +++++++++ aio-win32.c | 8 ++++++++ include/block/aio.h | 15 ++++++++------- 3 files changed, 25 insertions(+), 7 deletions(-) diff --git a/aio-posix.c b/aio-posix.c index 4a30b77..292ae84 100644 --- a/aio-posix.c +++ b/aio-posix.c @@ -238,6 +238,7 @@ bool aio_poll(AioContext *ctx, bool blocking) bool progress; int64_t timeout; + aio_context_acquire(ctx); was_dispatching = ctx->dispatching; progress = false; @@ -267,7 +268,13 @@ bool aio_poll(AioContext *ctx, bool blocking) timeout = blocking ? aio_compute_timeout(ctx) : 0; /* wait until next event */ + if (timeout) { + aio_context_release(ctx); + } ret = qemu_poll_ns((GPollFD *)pollfds, npfd, timeout); + if (timeout) { + aio_context_acquire(ctx); + } /* if we have any readable fds, dispatch event */ if (ret > 0) { @@ -285,5 +292,7 @@ bool aio_poll(AioContext *ctx, bool blocking) } aio_set_dispatching(ctx, was_dispatching); + aio_context_release(ctx); + return progress; } diff --git a/aio-win32.c b/aio-win32.c index e6f4ced..233d8f5 100644 --- a/aio-win32.c +++ b/aio-win32.c @@ -283,6 +283,7 @@ bool aio_poll(AioContext *ctx, bool blocking) int count; int timeout; + aio_context_acquire(ctx); have_select_revents = aio_prepare(ctx); if (have_select_revents) { blocking = false; @@ -323,7 +324,13 @@ bool aio_poll(AioContext *ctx, bool blocking) timeout = blocking ? qemu_timeout_ns_to_ms(aio_compute_timeout(ctx)) : 0; + if (timeout) { + aio_context_release(ctx); + } ret = WaitForMultipleObjects(count, events, FALSE, timeout); + if (timeout) { + aio_context_acquire(ctx); + } aio_set_dispatching(ctx, true); if (first && aio_bh_poll(ctx)) { @@ -349,5 +356,6 @@ bool aio_poll(AioContext *ctx, bool blocking) progress |= timerlistgroup_run_timers(&ctx->tlg); aio_set_dispatching(ctx, was_dispatching); + aio_context_release(ctx); return progress; } diff --git a/include/block/aio.h b/include/block/aio.h index 499efd0..e77409d 100644 --- a/include/block/aio.h +++ b/include/block/aio.h @@ -118,13 +118,14 @@ void aio_context_ref(AioContext *ctx); void aio_context_unref(AioContext *ctx); /* Take ownership of the AioContext. If the AioContext will be shared between - * threads, a thread must have ownership when calling aio_poll(). - * - * Note that multiple threads calling aio_poll() means timers, BHs, and - * callbacks may be invoked from a different thread than they were registered - * from. Therefore, code must use AioContext acquire/release or use - * fine-grained synchronization to protect shared state if other threads will - * be accessing it simultaneously. + * threads, and a thread does not want to be interrupted, it will have to + * take ownership around calls to aio_poll(). Otherwise, aio_poll() + * automatically takes care of calling aio_context_acquire and + * aio_context_release. + * + * Access to timers and BHs from a thread that has not acquired AioContext + * is possible. Access to callbacks for now must be done while the AioContext + * is owned by the thread (FIXME). */ void aio_context_acquire(AioContext *ctx); -- 2.3.0