Re: [Qemu-block] [PATCH v5 0/5] coroutine-lock: polymorphic CoQueue

[Fam Zheng]

On Sat, 02/03 10:39, Paolo Bonzini wrote:
> There are cases in which a queued coroutine must be restarted from
> non-coroutine context (with qemu_co_enter_next).  In this cases,
> qemu_co_enter_next also needs to be thread-safe, but it cannot use a
> CoMutex and so cannot qemu_co_queue_wait.  This happens in curl (which
> right now is rolling its own list of Coroutines) and will happen in
> Fam's NVMe driver as well.
> 
> This series extracts the idea of a polymorphic lockable object
> from my "scoped lock guard" proposal, and applies it to CoQueue.
> The implementation of QemuLockable is similar to C11 _Generic, but
> redone using the preprocessor and GCC builtins for compatibility.
> 
> In general, while a bit on the esoteric side, the functionality used
> to emulate _Generic is fairly old in GCC, and the builtins are already
> used by include/qemu/atomic.h; the series was tested with Fedora 27 (boot
> Damn Small Linux via http) and CentOS 6 (compiled only).
> 
> Paolo
> 
> v4->v5: fix checkpatch complaints

Queued, thanks.

Fam

Re: [Qemu-block] [PATCH v5 0/5] coroutine-lock: polymorphic CoQueue

[Stefan Hajnoczi]

On Sat, Feb 03, 2018 at 10:39:30AM -0500, Paolo Bonzini wrote:
> There are cases in which a queued coroutine must be restarted from
> non-coroutine context (with qemu_co_enter_next).  In this cases,
> qemu_co_enter_next also needs to be thread-safe, but it cannot use a
> CoMutex and so cannot qemu_co_queue_wait.  This happens in curl (which
> right now is rolling its own list of Coroutines) and will happen in
> Fam's NVMe driver as well.
> 
> This series extracts the idea of a polymorphic lockable object
> from my "scoped lock guard" proposal, and applies it to CoQueue.
> The implementation of QemuLockable is similar to C11 _Generic, but
> redone using the preprocessor and GCC builtins for compatibility.
> 
> In general, while a bit on the esoteric side, the functionality used
> to emulate _Generic is fairly old in GCC, and the builtins are already
> used by include/qemu/atomic.h; the series was tested with Fedora 27 (boot
> Damn Small Linux via http) and CentOS 6 (compiled only).
> 
> Paolo
> 
> v4->v5: fix checkpatch complaints
> 
> v3->v4: fix -O0 compilation [Fam]
> typos and copyright dates [Eric, Fam]
> improve CoQueue comments [Stefan]
> 
> Paolo Bonzini (5):
>   test-coroutine: add simple CoMutex test
>   lockable: add QemuLockable
>   coroutine-lock: convert CoQueue to use QemuLockable
>   coroutine-lock: make qemu_co_enter_next thread-safe
>   curl: convert to CoQueue
> 
>  block/curl.c| 20 ++
>  fsdev/qemu-fsdev-throttle.c |  4 +-
>  include/qemu/compiler.h | 40 +++
>  include/qemu/coroutine.h| 29 +-
>  include/qemu/lockable.h | 96 
> +
>  include/qemu/thread.h   |  5 +--
>  include/qemu/typedefs.h |  4 ++
>  tests/test-coroutine.c  | 75 ++-
>  util/qemu-coroutine-lock.c  | 22 +++
>  9 files changed, 256 insertions(+), 39 deletions(-)
>  create mode 100644 include/qemu/lockable.h
> 
> -- 
> 2.14.3
> 

Reviewed-by: Stefan Hajnoczi 


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[Qemu-block] [PATCH v5 0/5] coroutine-lock: polymorphic CoQueue

[Paolo Bonzini]

There are cases in which a queued coroutine must be restarted from
non-coroutine context (with qemu_co_enter_next).  In this cases,
qemu_co_enter_next also needs to be thread-safe, but it cannot use a
CoMutex and so cannot qemu_co_queue_wait.  This happens in curl (which
right now is rolling its own list of Coroutines) and will happen in
Fam's NVMe driver as well.

This series extracts the idea of a polymorphic lockable object
from my "scoped lock guard" proposal, and applies it to CoQueue.
The implementation of QemuLockable is similar to C11 _Generic, but
redone using the preprocessor and GCC builtins for compatibility.

In general, while a bit on the esoteric side, the functionality used
to emulate _Generic is fairly old in GCC, and the builtins are already
used by include/qemu/atomic.h; the series was tested with Fedora 27 (boot
Damn Small Linux via http) and CentOS 6 (compiled only).

Paolo

v4->v5: fix checkpatch complaints

v3->v4: fix -O0 compilation [Fam]
typos and copyright dates [Eric, Fam]
improve CoQueue comments [Stefan]

Paolo Bonzini (5):
  test-coroutine: add simple CoMutex test
  lockable: add QemuLockable
  coroutine-lock: convert CoQueue to use QemuLockable
  coroutine-lock: make qemu_co_enter_next thread-safe
  curl: convert to CoQueue

 block/curl.c| 20 ++
 fsdev/qemu-fsdev-throttle.c |  4 +-
 include/qemu/compiler.h | 40 +++
 include/qemu/coroutine.h| 29 +-
 include/qemu/lockable.h | 96 +
 include/qemu/thread.h   |  5 +--
 include/qemu/typedefs.h |  4 ++
 tests/test-coroutine.c  | 75 ++-
 util/qemu-coroutine-lock.c  | 22 +++
 9 files changed, 256 insertions(+), 39 deletions(-)
 create mode 100644 include/qemu/lockable.h

-- 
2.14.3