Features/CoroutineFnCleanup

Hand-written bdrv_co_* functions

1. bdrv_pread/bdrv_pwrite have different calling convention than bdrv_co_pread/bdrv_co_pwrite
   • Fix using Coccinelle
   • Switch bdrv_pread/bdrv_pwrite to generated_co_wrapper
2. Missing bdrv_co_pwrite_sync, bdrv_co_pwrite_zeroes
   • Adjust code in block/io.c and introduce generated_co_wrapper
3. Probably more will be found with custom matching tools (see below)

Annotations

1. Add coroutine_mixed_fn annotation; functions that call qemu_in_coroutine(). Includes:
   • all generated_co_wrapper functions
   • bdrv_create
   • bdrv_can_store_new_dirty_bitmap, bdrv_remove_persistent_dirty_bitmap
   • bdrv_drain_all_begin, bdrv_do_drained_begin, bdrv_do_drained_end
   • qio_channel_readv_full_all_eof, qio_channel_writev_full
   • qcow2_open, qcow2_has_zero_init
   • bdrv_qed_open
   • qmp_dispatch
   • nvme_get_free_req
   • schedule_next_request
2. Detect call from non-coroutine_fn/coroutine_mixed_fn to coroutine_fn (libclang/clang-tidy)
   • Remove coroutine_fn from callee, or add it to caller
   • Possibly add fixit to rewrite
3. Detect call from coroutine_fn to coroutine_mixed_fn (libclang/clang-tidy)
   • Use _co_ version instead.
   • Possibly add fixit to rewrite

Clang-query examples

Invoking clang-query:

1. Change definition of coroutine_fn to #define coroutine_fn __attribute__((annotate("coroutine")))
2. Invoke clang-query -p build-path block/io.c

Example of clang-query uses:

match functionDecl(allOf(unless(hasAttr("attr::Annotate")),hasDescendant(callExpr(callee(hasAttr("attr::Annotate"))).bind("callee"))))

call from non-coroutine_fn to coroutine_fn (doesn't actually check the string in the annotate attribute)

match varDecl(hasType(namedDecl(hasName("BlockDriver"))), hasInitializer(anything()))

declaration of BlockDriver struct, with initializer

match functionDecl(isExpansionInMainFile(), forEachDescendant(callExpr(callee(unless(functionDecl()))).bind("call"))).bind("root")'

indirect call

Clang references

https://devblogs.microsoft.com/cppblog/exploring-clang-tooling-part-1-extending-clang-tidy/

https://devblogs.microsoft.com/cppblog/exploring-clang-tooling-part-2-examining-the-clang-ast-with-clang-query/

https://devblogs.microsoft.com/cppblog/exploring-clang-tooling-part-3-rewriting-code-with-clang-tidy/