block/sheepdog: Fix silent sd_open(), sd_create() failures

[qemu.git] / async.c

diff --git a/async.c b/async.c
index 85cc6410c50259398beef693ec00b649823dcde3..6930185e64d382f12b82b53e881a981bc6e90db8 100644 (file)
--- a/async.c
+++ b/async.c
@@ -23,16 +23,15 @@
  */
 
 #include "qemu-common.h"
  */
 
 #include "qemu-common.h"

-#include "qemu-aio.h"
-#include "main-loop.h"
-
-/* Anchor of the list of Bottom Halves belonging to the context */
-static struct QEMUBH *first_bh;
+#include "block/aio.h"
+#include "block/thread-pool.h"
+#include "qemu/main-loop.h"

 
 /***********************************************************/
 /* bottom halves (can be seen as timers which expire ASAP) */
 
 struct QEMUBH {
 
 /***********************************************************/
 /* bottom halves (can be seen as timers which expire ASAP) */
 
 struct QEMUBH {

+    AioContext *ctx;

     QEMUBHFunc *cb;
     void *opaque;
     QEMUBH *next;
     QEMUBHFunc *cb;
     void *opaque;
     QEMUBH *next;


@@ -41,30 +40,41 @@ struct QEMUBH {
     bool deleted;
 };
 
     bool deleted;
 };
 

-QEMUBH *qemu_bh_new(QEMUBHFunc *cb, void *opaque)
+QEMUBH *aio_bh_new(AioContext *ctx, QEMUBHFunc *cb, void *opaque)

 {
     QEMUBH *bh;
     bh = g_malloc0(sizeof(QEMUBH));
 {
     QEMUBH *bh;
     bh = g_malloc0(sizeof(QEMUBH));

+    bh->ctx = ctx;

     bh->cb = cb;
     bh->opaque = opaque;
     bh->cb = cb;
     bh->opaque = opaque;

-    bh->next = first_bh;
-    first_bh = bh;
+    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;
 }
 
     return bh;
 }
 

-int qemu_bh_poll(void)
+/* Multiple occurrences of aio_bh_poll cannot be called concurrently */
+int aio_bh_poll(AioContext *ctx)

 {
     QEMUBH *bh, **bhp, *next;
     int ret;
 {
     QEMUBH *bh, **bhp, *next;
     int ret;

-    static int nesting = 0;

 
 

-    nesting++;
+    ctx->walking_bh++;

 
     ret = 0;
 
     ret = 0;

-    for (bh = first_bh; bh; bh = next) {
+    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;
         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;
             if (!bh->idle)
                 ret = 1;
             bh->idle = 0;


@@ -72,11 +82,12 @@ int qemu_bh_poll(void)
         }
     }
 
         }
     }
 

-    nesting--;
+    ctx->walking_bh--;

 
     /* remove deleted bhs */
 
     /* remove deleted bhs */

-    if (!nesting) {
-        bhp = &first_bh;
+    if (!ctx->walking_bh) {
+        qemu_mutex_lock(&ctx->bh_lock);
+        bhp = &ctx->first_bh;

         while (*bhp) {
             bh = *bhp;
             if (bh->deleted) {
         while (*bhp) {
             bh = *bhp;
             if (bh->deleted) {


@@ -86,6 +97,7 @@ int qemu_bh_poll(void)
                 bhp = &bh->next;
             }
         }
                 bhp = &bh->next;
             }
         }

+        qemu_mutex_unlock(&ctx->bh_lock);

     }
 
     return ret;
     }
 
     return ret;


@@ -95,48 +107,189 @@ void qemu_bh_schedule_idle(QEMUBH *bh)
 {
     if (bh->scheduled)
         return;
 {
     if (bh->scheduled)
         return;

-    bh->scheduled = 1;

     bh->idle = 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;
 }
 
 void qemu_bh_schedule(QEMUBH *bh)
 {
     if (bh->scheduled)
         return;

-    bh->scheduled = 1;

     bh->idle = 0;
     bh->idle = 0;

-    /* stop the currently executing CPU to execute the BH ASAP */
-    qemu_notify_event();
+    /* 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;
 }
 
 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;
     bh->deleted = 1;
 }
 
 void qemu_bh_delete(QEMUBH *bh)
 {
     bh->scheduled = 0;
     bh->deleted = 1;
 }
 

-void qemu_bh_update_timeout(uint32_t *timeout)
+static gboolean
+aio_ctx_prepare(GSource *source, gint    *timeout)

 {
 {

+    AioContext *ctx = (AioContext *) source;

     QEMUBH *bh;
     QEMUBH *bh;

+    int deadline;

 
 

-    for (bh = first_bh; bh; bh = bh->next) {
+    /* 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) {
                 /* idle bottom halves will be polled at least
                  * every 10ms */
         if (!bh->deleted && bh->scheduled) {
             if (bh->idle) {
                 /* idle bottom halves will be polled at least
                  * every 10ms */

-                *timeout = MIN(10, *timeout);
+                *timeout = 10;

             } else {
                 /* non-idle bottom halves will be executed
                  * immediately */
                 *timeout = 0;
             } else {
                 /* non-idle bottom halves will be executed
                  * immediately */
                 *timeout = 0;

-                break;
+                return true;

             }
         }
     }
             }
         }
     }

+
+    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;
+}
+
+static gboolean
+aio_ctx_check(GSource *source)
+{
+    AioContext *ctx = (AioContext *) source;
+    QEMUBH *bh;
+
+    for (bh = ctx->first_bh; bh; bh = bh->next) {
+        if (!bh->deleted && bh->scheduled) {
+            return true;
+       }
+    }
+    return aio_pending(ctx) || (timerlistgroup_deadline_ns(&ctx->tlg) == 0);
+}
+
+static gboolean
+aio_ctx_dispatch(GSource     *source,
+                 GSourceFunc  callback,
+                 gpointer     user_data)
+{
+    AioContext *ctx = (AioContext *) source;
+
+    assert(callback == NULL);
+    aio_poll(ctx, false);
+    return true;

 }
 
 }
 

+static void
+aio_ctx_finalize(GSource     *source)
+{
+    AioContext *ctx = (AioContext *) source;
+
+    thread_pool_free(ctx->thread_pool);
+    aio_set_event_notifier(ctx, &ctx->notifier, NULL);
+    event_notifier_cleanup(&ctx->notifier);
+    rfifolock_destroy(&ctx->lock);
+    qemu_mutex_destroy(&ctx->bh_lock);
+    g_array_free(ctx->pollfds, TRUE);
+    timerlistgroup_deinit(&ctx->tlg);
+}
+
+static GSourceFuncs aio_source_funcs = {
+    aio_ctx_prepare,
+    aio_ctx_check,
+    aio_ctx_dispatch,
+    aio_ctx_finalize
+};
+
+GSource *aio_get_g_source(AioContext *ctx)
+{
+    g_source_ref(&ctx->source);
+    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);
+}
+
+static void aio_rfifolock_cb(void *opaque)
+{
+    /* Kick owner thread in case they are blocked in aio_poll() */
+    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);
+    rfifolock_init(&ctx->lock, aio_rfifolock_cb, ctx);
+    event_notifier_init(&ctx->notifier, false);
+    aio_set_event_notifier(ctx, &ctx->notifier, 
+                           (EventNotifierHandler *)
+                           event_notifier_test_and_clear);
+    timerlistgroup_init(&ctx->tlg, aio_timerlist_notify, ctx);
+
+    return ctx;
+}
+
+void aio_context_ref(AioContext *ctx)
+{
+    g_source_ref(&ctx->source);
+}
+
+void aio_context_unref(AioContext *ctx)
+{
+    g_source_unref(&ctx->source);
+}
+
+void aio_context_acquire(AioContext *ctx)
+{
+    rfifolock_lock(&ctx->lock);
+}
+
+void aio_context_release(AioContext *ctx)
+{
+    rfifolock_unlock(&ctx->lock);
+}