Open 2.0 development tree

[qemu.git] / async.c

diff --git a/async.c b/async.c
index 72d268ae352510c0c0ca49a43e05d197e23c0d98..5fb3fa61dff7e7cd6c103fc5a2b5545b2d989ff0 100644 (file)
--- a/async.c
+++ b/async.c
@@ -24,6 +24,7 @@
 
 #include "qemu-common.h"
 #include "block/aio.h"
+#include "block/thread-pool.h"
 #include "qemu/main-loop.h"
 
 /***********************************************************/
@@ -46,11 +47,16 @@ QEMUBH *aio_bh_new(AioContext *ctx, QEMUBHFunc *cb, void *opaque)
     bh->ctx = ctx;
     bh->cb = cb;
     bh->opaque = opaque;
+    qemu_mutex_lock(&ctx->bh_lock);
     bh->next = ctx->first_bh;
+    /* Make sure that the members are ready before putting bh into list */
+    smp_wmb();
     ctx->first_bh = bh;
+    qemu_mutex_unlock(&ctx->bh_lock);
     return bh;
 }
 
+/* Multiple occurrences of aio_bh_poll cannot be called concurrently */
 int aio_bh_poll(AioContext *ctx)
 {
     QEMUBH *bh, **bhp, *next;
@@ -60,9 +66,15 @@ int aio_bh_poll(AioContext *ctx)
 
     ret = 0;
     for (bh = ctx->first_bh; bh; bh = next) {
+        /* Make sure that fetching bh happens before accessing its members */
+        smp_read_barrier_depends();
         next = bh->next;
         if (!bh->deleted && bh->scheduled) {
             bh->scheduled = 0;
+            /* Paired with write barrier in bh schedule to ensure reading for
+             * idle & callbacks coming after bh's scheduling.
+             */
+            smp_rmb();
             if (!bh->idle)
                 ret = 1;
             bh->idle = 0;
@@ -74,6 +86,7 @@ int aio_bh_poll(AioContext *ctx)
 
     /* remove deleted bhs */
     if (!ctx->walking_bh) {
+        qemu_mutex_lock(&ctx->bh_lock);
         bhp = &ctx->first_bh;
         while (*bhp) {
             bh = *bhp;
@@ -84,6 +97,7 @@ int aio_bh_poll(AioContext *ctx)
                 bhp = &bh->next;
             }
         }
+        qemu_mutex_unlock(&ctx->bh_lock);
     }
 
     return ret;
@@ -93,24 +107,38 @@ void qemu_bh_schedule_idle(QEMUBH *bh)
 {
     if (bh->scheduled)
         return;
-    bh->scheduled = 1;
     bh->idle = 1;
+    /* Make sure that idle & any writes needed by the callback are done
+     * before the locations are read in the aio_bh_poll.
+     */
+    smp_wmb();
+    bh->scheduled = 1;
 }
 
 void qemu_bh_schedule(QEMUBH *bh)
 {
     if (bh->scheduled)
         return;
-    bh->scheduled = 1;
     bh->idle = 0;
+    /* Make sure that idle & any writes needed by the callback are done
+     * before the locations are read in the aio_bh_poll.
+     */
+    smp_wmb();
+    bh->scheduled = 1;
     aio_notify(bh->ctx);
 }
 
+
+/* This func is async.
+ */
 void qemu_bh_cancel(QEMUBH *bh)
 {
     bh->scheduled = 0;
 }
 
+/* This func is async.The bottom half will do the delete action at the finial
+ * end.
+ */
 void qemu_bh_delete(QEMUBH *bh)
 {
     bh->scheduled = 0;
@@ -122,7 +150,10 @@ aio_ctx_prepare(GSource *source, gint    *timeout)
 {
     AioContext *ctx = (AioContext *) source;
     QEMUBH *bh;
+    int deadline;
 
+    /* We assume there is no timeout already supplied */
+    *timeout = -1;
     for (bh = ctx->first_bh; bh; bh = bh->next) {
         if (!bh->deleted && bh->scheduled) {
             if (bh->idle) {
@@ -138,6 +169,14 @@ aio_ctx_prepare(GSource *source, gint    *timeout)
         }
     }
 
+    deadline = qemu_timeout_ns_to_ms(timerlistgroup_deadline_ns(&ctx->tlg));
+    if (deadline == 0) {
+        *timeout = 0;
+        return true;
+    } else {
+        *timeout = qemu_soonest_timeout(*timeout, deadline);
+    }
+
     return false;
 }
 
@@ -152,7 +191,7 @@ aio_ctx_check(GSource *source)
             return true;
        }
     }
-    return aio_pending(ctx);
+    return aio_pending(ctx) || (timerlistgroup_deadline_ns(&ctx->tlg) == 0);
 }
 
 static gboolean
@@ -172,8 +211,12 @@ aio_ctx_finalize(GSource     *source)
 {
     AioContext *ctx = (AioContext *) source;
 
-    aio_set_event_notifier(ctx, &ctx->notifier, NULL, NULL);
+    thread_pool_free(ctx->thread_pool);
+    aio_set_event_notifier(ctx, &ctx->notifier, NULL);
     event_notifier_cleanup(&ctx->notifier);
+    qemu_mutex_destroy(&ctx->bh_lock);
+    g_array_free(ctx->pollfds, TRUE);
+    timerlistgroup_deinit(&ctx->tlg);
 }
 
 static GSourceFuncs aio_source_funcs = {
@@ -189,19 +232,36 @@ GSource *aio_get_g_source(AioContext *ctx)
     return &ctx->source;
 }
 
+ThreadPool *aio_get_thread_pool(AioContext *ctx)
+{
+    if (!ctx->thread_pool) {
+        ctx->thread_pool = thread_pool_new(ctx);
+    }
+    return ctx->thread_pool;
+}
+
 void aio_notify(AioContext *ctx)
 {
     event_notifier_set(&ctx->notifier);
 }
 
+static void aio_timerlist_notify(void *opaque)
+{
+    aio_notify(opaque);
+}
+
 AioContext *aio_context_new(void)
 {
     AioContext *ctx;
     ctx = (AioContext *) g_source_new(&aio_source_funcs, sizeof(AioContext));
+    ctx->pollfds = g_array_new(FALSE, FALSE, sizeof(GPollFD));
+    ctx->thread_pool = NULL;
+    qemu_mutex_init(&ctx->bh_lock);
     event_notifier_init(&ctx->notifier, false);
     aio_set_event_notifier(ctx, &ctx->notifier, 
                            (EventNotifierHandler *)
-                           event_notifier_test_and_clear, NULL);
+                           event_notifier_test_and_clear);
+    timerlistgroup_init(&ctx->tlg, aio_timerlist_notify, ctx);
 
     return ctx;
 }