[PATCH 04/11] block: introduce bdrv_debug_wait_break

[Vladimir Sementsov-Ogievskiy]

Add a handler to wait for the break to happen in coroutine context. It
will be used in further commit.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 include/block/block.h     |  1 +
 include/block/block_int.h |  1 +
 block.c                   | 11 +++++++++++
 block/blkdebug.c          | 16 ++++++++++++++++
 4 files changed, 29 insertions(+)

diff --git a/include/block/block.h b/include/block/block.h
index b3f6e509d4..e133adf54f 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -648,6 +648,7 @@ int bdrv_debug_breakpoint(BlockDriverState *bs, const char 
*event,
 int bdrv_debug_remove_breakpoint(BlockDriverState *bs, const char *tag);
 int bdrv_debug_resume(BlockDriverState *bs, const char *tag);
 bool bdrv_debug_is_suspended(BlockDriverState *bs, const char *tag);
+void coroutine_fn bdrv_debug_wait_break(BlockDriverState *bs, const char *tag);
 
 /**
  * bdrv_get_aio_context:
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 50af58af75..89e6904fc7 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -502,6 +502,7 @@ struct BlockDriver {
         const char *tag);
     int (*bdrv_debug_resume)(BlockDriverState *bs, const char *tag);
     bool (*bdrv_debug_is_suspended)(BlockDriverState *bs, const char *tag);
+    void (*bdrv_debug_wait_break)(BlockDriverState *bs, const char *tag);
 
     void (*bdrv_refresh_limits)(BlockDriverState *bs, Error **errp);
 
diff --git a/block.c b/block.c
index 001453105e..3ea088b9fb 100644
--- a/block.c
+++ b/block.c
@@ -5702,6 +5702,17 @@ bool bdrv_debug_is_suspended(BlockDriverState *bs, const 
char *tag)
     return false;
 }
 
+void coroutine_fn bdrv_debug_wait_break(BlockDriverState *bs, const char *tag)
+{
+    while (bs && bs->drv && !bs->drv->bdrv_debug_wait_break) {
+        bs = bdrv_primary_bs(bs);
+    }
+
+    if (bs && bs->drv && bs->drv->bdrv_debug_wait_break) {
+        bs->drv->bdrv_debug_wait_break(bs, tag);
+    }
+}
+
 /* backing_file can either be relative, or absolute, or a protocol.  If it is
  * relative, it must be relative to the chain.  So, passing in bs->filename
  * from a BDS as backing_file should not be done, as that may be relative to
diff --git a/block/blkdebug.c b/block/blkdebug.c
index 2c0b9b0ee8..10b7c38467 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -57,6 +57,7 @@ typedef struct BDRVBlkdebugState {
     QLIST_HEAD(, BlkdebugRule) rules[BLKDBG__MAX];
     QSIMPLEQ_HEAD(, BlkdebugRule) active_rules;
     QLIST_HEAD(, BlkdebugSuspendedReq) suspended_reqs;
+    CoQueue break_waiters;
 } BDRVBlkdebugState;
 
 typedef struct BlkdebugAIOCB {
@@ -467,6 +468,8 @@ static int blkdebug_open(BlockDriverState *bs, QDict 
*options, int flags,
     int ret;
     uint64_t align;
 
+    qemu_co_queue_init(&s->break_waiters);
+
     opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
     if (!qemu_opts_absorb_qdict(opts, options, errp)) {
         ret = -EINVAL;
@@ -785,6 +788,8 @@ static void suspend_request(BlockDriverState *bs, 
BlkdebugRule *rule)
     remove_rule(rule);
     QLIST_INSERT_HEAD(&s->suspended_reqs, &r, next);
 
+    qemu_co_queue_restart_all(&s->break_waiters);
+
     if (!qtest_enabled()) {
         printf("blkdebug: Suspended request '%s'\n", r.tag);
     }
@@ -922,6 +927,16 @@ static bool blkdebug_debug_is_suspended(BlockDriverState 
*bs, const char *tag)
     return false;
 }
 
+static void coroutine_fn
+blkdebug_debug_wait_break(BlockDriverState *bs, const char *tag)
+{
+    BDRVBlkdebugState *s = bs->opaque;
+
+    while (!blkdebug_debug_is_suspended(bs, tag)) {
+        qemu_co_queue_wait(&s->break_waiters, NULL);
+    }
+}
+
 static int64_t blkdebug_getlength(BlockDriverState *bs)
 {
     return bdrv_getlength(bs->file->bs);
@@ -1048,6 +1063,7 @@ static BlockDriver bdrv_blkdebug = {
                                 = blkdebug_debug_remove_breakpoint,
     .bdrv_debug_resume          = blkdebug_debug_resume,
     .bdrv_debug_is_suspended    = blkdebug_debug_is_suspended,
+    .bdrv_debug_wait_break      = blkdebug_debug_wait_break,
 
     .strong_runtime_opts        = blkdebug_strong_runtime_opts,
 };
-- 
2.29.2