Commit a153bf52 authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Stefan Hajnoczi
Browse files

aio-posix: partially inline aio_dispatch into aio_poll 



This patch prepares for the removal of unnecessary lockcnt inc/dec pairs.
Extract the dispatching loop for file descriptor handlers into a new
function aio_dispatch_handlers, and then inline aio_dispatch into
aio_poll.

aio_dispatch can now become void.

Reviewed-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: default avatarFam Zheng <famz@redhat.com>
Reviewed-by: default avatarDaniel P. Berrange <berrange@redhat.com>
Message-id: 20170213135235.12274-17-pbonzini@redhat.com
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent b9e413dd

include/block/aio.h

+1 −5
Original line number Diff line number Diff line
@@ -310,12 +310,8 @@ bool aio_pending(AioContext *ctx); 
/* Dispatch any pending callbacks from the GSource attached to the AioContext.

 *

 * This is used internally in the implementation of the GSource.

 *

 * @dispatch_fds: true to process fds, false to skip them

 *                (can be used as an optimization by callers that know there

 *                are no fds ready)

 */

bool aio_dispatch(AioContext *ctx, bool dispatch_fds);

void aio_dispatch(AioContext *ctx);



/* Progress in completing AIO work to occur.  This can issue new pending

 * aio as a result of executing I/O completion or bh callbacks.

util/aio-posix.c

+14 −30
Original line number Diff line number Diff line
@@ -386,12 +386,6 @@ static bool aio_dispatch_handlers(AioContext *ctx) 
    AioHandler *node, *tmp;

    bool progress = false;



    /*

     * We have to walk very carefully in case aio_set_fd_handler is

     * called while we're walking.

     */

    qemu_lockcnt_inc(&ctx->list_lock);



    QLIST_FOREACH_SAFE_RCU(node, &ctx->aio_handlers, node, tmp) {

        int revents;
@@ -426,33 +420,18 @@ static bool aio_dispatch_handlers(AioContext *ctx) 
        }

    }



    qemu_lockcnt_dec(&ctx->list_lock);

    return progress;

}



/*

 * Note that dispatch_fds == false has the side-effect of post-poning the

 * freeing of deleted handlers.

 */

bool aio_dispatch(AioContext *ctx, bool dispatch_fds)

void aio_dispatch(AioContext *ctx)

{

    bool progress;



    /*

     * If there are callbacks left that have been queued, we need to call them.

     * Do not call select in this case, because it is possible that the caller

     * does not need a complete flush (as is the case for aio_poll loops).

     */

    progress = aio_bh_poll(ctx);



    if (dispatch_fds) {

        progress |= aio_dispatch_handlers(ctx);

    }

    aio_bh_poll(ctx);



    /* Run our timers */

    progress |= timerlistgroup_run_timers(&ctx->tlg);

    qemu_lockcnt_inc(&ctx->list_lock);

    aio_dispatch_handlers(ctx);

    qemu_lockcnt_dec(&ctx->list_lock);



    return progress;

    timerlistgroup_run_timers(&ctx->tlg);

}



/* These thread-local variables are used only in a small part of aio_poll
@@ -702,11 +681,16 @@ bool aio_poll(AioContext *ctx, bool blocking) 
    npfd = 0;

    qemu_lockcnt_dec(&ctx->list_lock);



    /* Run dispatch even if there were no readable fds to run timers */

    if (aio_dispatch(ctx, ret > 0)) {

        progress = true;

    progress |= aio_bh_poll(ctx);



    if (ret > 0) {

        qemu_lockcnt_inc(&ctx->list_lock);

        progress |= aio_dispatch_handlers(ctx);

        qemu_lockcnt_dec(&ctx->list_lock);

    }



    progress |= timerlistgroup_run_timers(&ctx->tlg);



    return progress;

}

util/aio-win32.c

+4 −9
Original line number Diff line number Diff line
@@ -309,16 +309,11 @@ static bool aio_dispatch_handlers(AioContext *ctx, HANDLE event) 
    return progress;

}



bool aio_dispatch(AioContext *ctx, bool dispatch_fds)

void aio_dispatch(AioContext *ctx)

{

    bool progress;



    progress = aio_bh_poll(ctx);

    if (dispatch_fds) {

        progress |= aio_dispatch_handlers(ctx, INVALID_HANDLE_VALUE);

    }

    progress |= timerlistgroup_run_timers(&ctx->tlg);

    return progress;

    aio_bh_poll(ctx);

    aio_dispatch_handlers(ctx, INVALID_HANDLE_VALUE);

    timerlistgroup_run_timers(&ctx->tlg);

}



bool aio_poll(AioContext *ctx, bool blocking)

util/async.c

+1 −1
Original line number Diff line number Diff line
@@ -258,7 +258,7 @@ aio_ctx_dispatch(GSource *source, 
    AioContext *ctx = (AioContext *) source;



    assert(callback == NULL);

    aio_dispatch(ctx, true);

    aio_dispatch(ctx);

    return true;

}