Re: [PATCH v2 3/9] nbd/server.c: add missing coroutine_fn annotations

[Vladimir Sementsov-Ogievskiy]

On 11/4/22 12:56, Emanuele Giuseppe Esposito wrote:

These functions end up calling bdrv_*() implemented as generated_co_wrapper
functions.

Same here. Sorry that I joined only on v3.

In past we had a lot of "coroutine wrappers", each IO function in block/io.c 
and many in block.c had two variants:

coroutine_fn bdrv_co_foo(...)

and a wrapper

bdrv_foo(...)

And that wrapper is not a coroutine_fn, it's for calling from any context: 
coroutine or not. Now many of these wrappers are auto-generated, you may find 
them in build/block/block-gen.c after successful make.

"generated_co_wrapper" is a sign for code generation script to generate the 
wrapper code.

In addition, they also happen to be always called in coroutine context,
meaning all callers are coroutine_fn.
This means that the g_c_w function will enter the qemu_in_coroutine()
case and eventually suspend (or in other words call qemu_coroutine_yield()).
Therefore we need to mark such functions coroutine_fn too.

Signed-off-by: Emanuele Giuseppe Esposito <eespo...@redhat.com>
---
  nbd/server.c | 21 ++++++++++++---------
  1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/nbd/server.c b/nbd/server.c
index ada16089f3..e2eec0cf46 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -2141,8 +2141,9 @@ static int nbd_extent_array_add(NBDExtentArray *ea,
      return 0;
  }

-static int blockstatus_to_extents(BlockDriverState *bs, uint64_t offset,

-                                  uint64_t bytes, NBDExtentArray *ea)
+static int coroutine_fn blockstatus_to_extents(BlockDriverState *bs,
+                                               uint64_t offset, uint64_t bytes,
+                                               NBDExtentArray *ea)
  {
      while (bytes) {
          uint32_t flags;
@@ -2168,8 +2169,9 @@ static int blockstatus_to_extents(BlockDriverState *bs, 
uint64_t offset,
      return 0;
  }

-static int blockalloc_to_extents(BlockDriverState *bs, uint64_t offset,

-                                 uint64_t bytes, NBDExtentArray *ea)
+static int coroutine_fn blockalloc_to_extents(BlockDriverState *bs,
+                                              uint64_t offset, uint64_t bytes,
+                                              NBDExtentArray *ea)
  {
      while (bytes) {
          int64_t num;
@@ -2220,11 +2222,12 @@ static int nbd_co_send_extents(NBDClient *client, 
uint64_t handle,
  }

/* Get block status from the exported device and send it to the client */

-static int nbd_co_send_block_status(NBDClient *client, uint64_t handle,
-                                    BlockDriverState *bs, uint64_t offset,
-                                    uint32_t length, bool dont_fragment,
-                                    bool last, uint32_t context_id,
-                                    Error **errp)
+static int
+coroutine_fn nbd_co_send_block_status(NBDClient *client, uint64_t handle,
+                                      BlockDriverState *bs, uint64_t offset,
+                                      uint32_t length, bool dont_fragment,
+                                      bool last, uint32_t context_id,
+                                      Error **errp)
  {
      int ret;
      unsigned int nb_extents = dont_fragment ? 1 : 
NBD_MAX_BLOCK_STATUS_EXTENTS;

--
Best regards,
Vladimir