blkdebug: move post-resume handling to resume_req_by_tag

We want to move qemu_coroutine_yield() after the loop on rules,
because QLIST_FOREACH_SAFE is wrong if the rule list is modified
while the coroutine has yielded.  Therefore move the suspended
request to the heap and clean it up from the remove side.
All that is left is for blkdebug_debug_event to handle the
yielding.

Co-developed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210614082931.24925-3-eesposit@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

1 files changed, 18 insertions, 13 deletions

diff --git a/block/blkdebug.c b/block/blkdebug.c
index 5ccbfcab42..e8fdf7b056 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -775,25 +775,20 @@ static void blkdebug_close(BlockDriverState *bs)
 static void suspend_request(BlockDriverState *bs, BlkdebugRule *rule)
 {
     BDRVBlkdebugState *s = bs->opaque;
-    BlkdebugSuspendedReq r;
+    BlkdebugSuspendedReq *r;
 
-    r = (BlkdebugSuspendedReq) {
-        .co         = qemu_coroutine_self(),
-        .tag        = g_strdup(rule->options.suspend.tag),
-    };
+    r = g_new(BlkdebugSuspendedReq, 1);
+
+    r->co         = qemu_coroutine_self();
+    r->tag        = g_strdup(rule->options.suspend.tag);
 
     remove_rule(rule);
-    QLIST_INSERT_HEAD(&s->suspended_reqs, &r, next);
+    QLIST_INSERT_HEAD(&s->suspended_reqs, r, next);
 
     if (!qtest_enabled()) {
-        printf("blkdebug: Suspended request '%s'\n", r.tag);
+        printf("blkdebug: Suspended request '%s'\n", r->tag);
     }
     qemu_coroutine_yield();
-    if (!qtest_enabled()) {
-        printf("blkdebug: Resuming request '%s'\n", r.tag);
-    }
-
-    g_free(r.tag);
 }
 
 static bool process_rule(BlockDriverState *bs, struct BlkdebugRule *rule,
@@ -880,8 +875,18 @@ retry:
      */
     QLIST_FOREACH(r, &s->suspended_reqs, next) {
         if (!strcmp(r->tag, tag)) {
+            Coroutine *co = r->co;
+
+            if (!qtest_enabled()) {
+                printf("blkdebug: Resuming request '%s'\n", r->tag);
+            }
+
             QLIST_REMOVE(r, next);
-            qemu_coroutine_enter(r->co);
+            g_free(r->tag);
+            g_free(r);
+
+            qemu_coroutine_enter(co);
+
             if (all) {
                 goto retry;
             }