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

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

Hi,

This series seems to have some coding style problems. See output below for
more information:

Type: series
Message-id: 20180201212917.18131-1-pbonzini@redhat.com
Subject: [Qemu-devel] [PATCH v4 0/5] coroutine-lock: polymorphic CoQueue

=== TEST SCRIPT BEGIN ===
#!/bin/bash

BASE=base
n=1
total=$(git log --oneline $BASE.. | wc -l)
failed=0

git config --local diff.renamelimit 0
git config --local diff.renames True

commits="$(git log --format=%H --reverse $BASE..)"
for c in $commits; do
    echo "Checking PATCH $n/$total: $(git log -n 1 --format=%s $c)..."
    if ! git show $c --format=email | ./scripts/checkpatch.pl --mailback -; then
        failed=1
        echo
    fi
    n=$((n+1))
done

exit $failed
=== TEST SCRIPT END ===

Updating 3c8cf5a9c21ff8782164d1def7f44bd888713384
Switched to a new branch 'test'
87da24d9ea curl: convert to CoQueue
a94c2af350 coroutine-lock: make qemu_co_enter_next thread-safe
57eba09708 coroutine-lock: convert CoQueue to use QemuLockable
6efa617c67 lockable: add QemuLockable
1423cb0ab4 test-coroutine: add simple CoMutex test

=== OUTPUT BEGIN ===
Checking PATCH 1/5: test-coroutine: add simple CoMutex test...
ERROR: do not initialise statics to 0 or NULL
#30: FILE: tests/test-coroutine.c:198:
+static bool locked = false;

total: 1 errors, 0 warnings, 74 lines checked

Your patch has style problems, please review.  If any of these errors
are false positives report them to the maintainer, see
CHECKPATCH in MAINTAINERS.

Checking PATCH 2/5: lockable: add QemuLockable...
WARNING: line over 80 characters
#58: FILE: include/qemu/compiler.h:144:
+#define QEMU_GENERIC2(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC1(x, __VA_ARGS__))

WARNING: line over 80 characters
#59: FILE: include/qemu/compiler.h:145:
+#define QEMU_GENERIC3(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC2(x, __VA_ARGS__))

WARNING: line over 80 characters
#60: FILE: include/qemu/compiler.h:146:
+#define QEMU_GENERIC4(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC3(x, __VA_ARGS__))

WARNING: line over 80 characters
#61: FILE: include/qemu/compiler.h:147:
+#define QEMU_GENERIC5(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC4(x, __VA_ARGS__))

WARNING: line over 80 characters
#62: FILE: include/qemu/compiler.h:148:
+#define QEMU_GENERIC6(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC5(x, __VA_ARGS__))

WARNING: line over 80 characters
#63: FILE: include/qemu/compiler.h:149:
+#define QEMU_GENERIC7(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC6(x, __VA_ARGS__))

WARNING: line over 80 characters
#64: FILE: include/qemu/compiler.h:150:
+#define QEMU_GENERIC8(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC7(x, __VA_ARGS__))

WARNING: line over 80 characters
#65: FILE: include/qemu/compiler.h:151:
+#define QEMU_GENERIC9(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC8(x, __VA_ARGS__))

WARNING: line over 80 characters
#66: FILE: include/qemu/compiler.h:152:
+#define QEMU_GENERIC10(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC9(x, __VA_ARGS__))

WARNING: line over 80 characters
#124: FILE: include/qemu/lockable.h:28:
+ * to QEMU_MAKE_LOCKABLE.  For optimized builds, we can rely on dead-code elimination

WARNING: architecture specific defines should be avoided
#127: FILE: include/qemu/lockable.h:31:
+#ifdef __OPTIMIZE__

total: 0 errors, 11 warnings, 242 lines checked

Your patch has style problems, please review.  If any of these errors
are false positives report them to the maintainer, see
CHECKPATCH in MAINTAINERS.
Checking PATCH 3/5: coroutine-lock: convert CoQueue to use QemuLockable...
Checking PATCH 4/5: coroutine-lock: make qemu_co_enter_next thread-safe...
Checking PATCH 5/5: curl: convert to CoQueue...
=== OUTPUT END ===

Test command exited with code: 1


---
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Please send your feedback to patchew-devel@freelists.org

On Fri, Feb 2, 2018 at 6:01 AM,  <no-reply@patchew.org> wrote:
> === OUTPUT BEGIN ===
> Checking PATCH 1/5: test-coroutine: add simple CoMutex test...
> ERROR: do not initialise statics to 0 or NULL
> #30: FILE: tests/test-coroutine.c:198:
> +static bool locked = false;
>
> total: 1 errors, 0 warnings, 74 lines checked

I think we should fix this one too. Otherwise,

Reviewed-by: Fam Zheng <famz@redhat.com>


>
> Your patch has style problems, please review.  If any of these errors
> are false positives report them to the maintainer, see
> CHECKPATCH in MAINTAINERS.
>
> Checking PATCH 2/5: lockable: add QemuLockable...
> WARNING: line over 80 characters
> #58: FILE: include/qemu/compiler.h:144:
> +#define QEMU_GENERIC2(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC1(x, __VA_ARGS__))
>
> WARNING: line over 80 characters
> #59: FILE: include/qemu/compiler.h:145:
> +#define QEMU_GENERIC3(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC2(x, __VA_ARGS__))
>
> WARNING: line over 80 characters
> #60: FILE: include/qemu/compiler.h:146:
> +#define QEMU_GENERIC4(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC3(x, __VA_ARGS__))
>
> WARNING: line over 80 characters
> #61: FILE: include/qemu/compiler.h:147:
> +#define QEMU_GENERIC5(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC4(x, __VA_ARGS__))
>
> WARNING: line over 80 characters
> #62: FILE: include/qemu/compiler.h:148:
> +#define QEMU_GENERIC6(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC5(x, __VA_ARGS__))
>
> WARNING: line over 80 characters
> #63: FILE: include/qemu/compiler.h:149:
> +#define QEMU_GENERIC7(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC6(x, __VA_ARGS__))
>
> WARNING: line over 80 characters
> #64: FILE: include/qemu/compiler.h:150:
> +#define QEMU_GENERIC8(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC7(x, __VA_ARGS__))
>
> WARNING: line over 80 characters
> #65: FILE: include/qemu/compiler.h:151:
> +#define QEMU_GENERIC9(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC8(x, __VA_ARGS__))
>
> WARNING: line over 80 characters
> #66: FILE: include/qemu/compiler.h:152:
> +#define QEMU_GENERIC10(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC9(x, __VA_ARGS__))
>
> WARNING: line over 80 characters
> #124: FILE: include/qemu/lockable.h:28:
> + * to QEMU_MAKE_LOCKABLE.  For optimized builds, we can rely on dead-code elimination
>
> WARNING: architecture specific defines should be avoided
> #127: FILE: include/qemu/lockable.h:31:
> +#ifdef __OPTIMIZE__
>
> total: 0 errors, 11 warnings, 242 lines checked
>
> Your patch has style problems, please review.  If any of these errors
> are false positives report them to the maintainer, see
> CHECKPATCH in MAINTAINERS.
> Checking PATCH 3/5: coroutine-lock: convert CoQueue to use QemuLockable...
> Checking PATCH 4/5: coroutine-lock: make qemu_co_enter_next thread-safe...
> Checking PATCH 5/5: curl: convert to CoQueue...
> === OUTPUT END ===
>
> Test command exited with code: 1
>
>
> ---
> Email generated automatically by Patchew [http://patchew.org/].
> Please send your feedback to patchew-devel@freelists.org