[Qemu-devel] RFC: [PATCH 0/5] Explicitly annotating coroutine_fn functions

[Charlie Shepherd <charlie@ctshepherd.com>]

This patch series is a follow up to a previous RFC about converting functions
that dynamically yield execution depending on whether they are in executing in
a coroutine context or not to be explicitly statically annotated. This change
is necessary for the GSoC CPC project, but was also agreed in an IRC
conversation on #qemu to be benefical overall if it can be upstream before the
end of the project. This is an update to see if the approach I'm taking to
implementing this conversion is correct.

In order to statically check the tree to ensure the annotations are correct,
I've been using CPC to compile the QEMU tree. This does a source to source
translation to convert coroutine code to continuation-passing style (the
purpose of the GSoC project), but as a side benefit statically checks
annotations (any functions annotated with coroutine_fn are transformed into
CPS, so have a different "calling style" to the standard C convention).

In order to compile the tree with CPC:
 $ git clone git://github.com/kerneis/cpc.git
 $ cd cpc
 $ make
 $ ./configure
 $ make
 $ cd ..
 $ export CPC=$(pwd)/cpc/bin/cpc
 $ cd qemu
 $ mkdir -p bin/cpc
 $ cd bin/cpc
 $ ../../configure --enable-debug --disable-werror  --target-list=x86_64-softmmu     --cc="$CPC"     --extra-cflags="--noMakeStaticGlobal --useLogicalOperators --useCaseRange --save-temps -U__SSE2__ -w -Dcoroutine_fn='__attribute__((__cps__))' --docpsInference  --warnall "
 $ make


Charlie Shepherd (5):
  Add an explanation of when a function should be marked
  qemu_coroutine_self should not be marked coroutine_fn
  Convert BlockDriver to explicit coroutine annotations
  Convert block functions to coroutine versions
  Convert block layer callers' annotations

 block.c                       | 247 ++++++++++++++++++++++--------------------
 block/blkdebug.c              |  10 +-
 block/blkverify.c             |   4 +-
 block/bochs.c                 |  12 +-
 block/cloop.c                 |  10 +-
 block/cow.c                   |  20 ++--
 block/curl.c                  |  12 +-
 block/dmg.c                   |  14 +--
 block/mirror.c                |   4 +-
 block/nbd.c                   |  28 ++---
 block/parallels.c             |   6 +-
 block/qcow.c                  |  14 +--
 block/qcow2-cluster.c         |   8 +-
 block/qcow2.c                 |  66 ++++++++---
 block/qcow2.h                 |   6 +-
 block/qed.c                   |   8 +-
 block/raw-posix.c             |  34 +++---
 block/raw.c                   |   8 +-
 block/sheepdog.c              |  24 ++--
 block/snapshot.c              |  32 +++++-
 block/ssh.c                   |  14 +--
 block/vdi.c                   |  16 +--
 block/vhdx.c                  |   4 +-
 block/vmdk.c                  |  46 ++++----
 block/vpc.c                   |  16 +--
 block/vvfat.c                 |  32 +++---
 blockjob.c                    |   2 +-
 coroutine-ucontext.c          |   2 +-
 include/block/block.h         |  37 ++++---
 include/block/block_int.h     |  10 +-
 include/block/blockjob.h      |   2 +-
 include/block/coroutine.h     |   9 +-
 include/block/coroutine_int.h |   2 +-
 nbd.c                         |   4 +-
 qemu-coroutine-lock.c         |   4 +-
 qemu-img.c                    |  54 +++++++--
 qemu-io-cmds.c                |  12 +-
 37 files changed, 477 insertions(+), 356 deletions(-)

-- 
1.8.3.2