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| author | Paolo Bonzini <pbonzini@redhat.com> | 2017-06-06 16:46:26 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2017-06-07 18:22:03 +0200 |
| commit | ac06724a715864942e2b5e28f92d5d5421f0a0b0 (patch) | |
| tree | 8eeb9a6aeff09669b65573b1d856426cdf87d8bd /docs/spin/win32-qemu-event.promela | |
| parent | 90bb0c04214545beb75044a2742f711335103269 (diff) | |
docs: create config/, devel/ and spin/ subdirectories
Developer documentation should be its own manual. As a start, move all
developer-oriented files to a separate directory.
Also move non-text files to their own directories: docs/config/ for
QEMU -readconfig input, and docs/spin/ for formal models to be used
with the SPIN model checker.
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'docs/spin/win32-qemu-event.promela')
| -rw-r--r-- | docs/spin/win32-qemu-event.promela | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/docs/spin/win32-qemu-event.promela b/docs/spin/win32-qemu-event.promela new file mode 100644 index 0000000000..c446a71555 --- /dev/null +++ b/docs/spin/win32-qemu-event.promela @@ -0,0 +1,98 @@ +/* + * This model describes the implementation of QemuEvent in + * util/qemu-thread-win32.c. + * + * Author: Paolo Bonzini <pbonzini@redhat.com> + * + * This file is in the public domain. If you really want a license, + * the WTFPL will do. + * + * To verify it: + * spin -a docs/event.promela + * gcc -O2 pan.c -DSAFETY + * ./a.out + */ + +bool event; +int value; + +/* Primitives for a Win32 event */ +#define RAW_RESET event = false +#define RAW_SET event = true +#define RAW_WAIT do :: event -> break; od + +#if 0 +/* Basic sanity checking: test the Win32 event primitives */ +#define RESET RAW_RESET +#define SET RAW_SET +#define WAIT RAW_WAIT +#else +/* Full model: layer a userspace-only fast path on top of the RAW_* + * primitives. SET/RESET/WAIT have exactly the same semantics as + * RAW_SET/RAW_RESET/RAW_WAIT, but try to avoid invoking them. + */ +#define EV_SET 0 +#define EV_FREE 1 +#define EV_BUSY -1 + +int state = EV_FREE; + +int xchg_result; +#define SET if :: state != EV_SET -> \ + atomic { /* xchg_result=xchg(state, EV_SET) */ \ + xchg_result = state; \ + state = EV_SET; \ + } \ + if :: xchg_result == EV_BUSY -> RAW_SET; \ + :: else -> skip; \ + fi; \ + :: else -> skip; \ + fi + +#define RESET if :: state == EV_SET -> atomic { state = state | EV_FREE; } \ + :: else -> skip; \ + fi + +int tmp1, tmp2; +#define WAIT tmp1 = state; \ + if :: tmp1 != EV_SET -> \ + if :: tmp1 == EV_FREE -> \ + RAW_RESET; \ + atomic { /* tmp2=cas(state, EV_FREE, EV_BUSY) */ \ + tmp2 = state; \ + if :: tmp2 == EV_FREE -> state = EV_BUSY; \ + :: else -> skip; \ + fi; \ + } \ + if :: tmp2 == EV_SET -> tmp1 = EV_SET; \ + :: else -> tmp1 = EV_BUSY; \ + fi; \ + :: else -> skip; \ + fi; \ + assert(tmp1 != EV_FREE); \ + if :: tmp1 == EV_BUSY -> RAW_WAIT; \ + :: else -> skip; \ + fi; \ + :: else -> skip; \ + fi +#endif + +active proctype waiter() +{ + if + :: !value -> + RESET; + if + :: !value -> WAIT; + :: else -> skip; + fi; + :: else -> skip; + fi; + assert(value); +} + +active proctype notifier() +{ + value = true; + SET; +} |