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author | Chanho Park <chanho61.park@samsung.com> | 2014-09-05 20:35:53 +0900 |
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committer | Chanho Park <chanho61.park@samsung.com> | 2014-09-05 20:35:53 +0900 |
commit | 16b1353a36171ae06d63fd309f4772dbfb1da113 (patch) | |
tree | cf6c297ee81aba0d9b47f23d78a889667e7bce48 /async.c | |
parent | a15119db2ff5c2fdfdeb913b297bf8aa3399132e (diff) | |
download | qemu-16b1353a36171ae06d63fd309f4772dbfb1da113.tar.gz qemu-16b1353a36171ae06d63fd309f4772dbfb1da113.tar.bz2 qemu-16b1353a36171ae06d63fd309f4772dbfb1da113.zip |
Imported Upstream version 2.1.0upstream/2.1.0
Diffstat (limited to 'async.c')
-rw-r--r-- | async.c | 33 |
1 files changed, 28 insertions, 5 deletions
@@ -26,6 +26,7 @@ #include "block/aio.h" #include "block/thread-pool.h" #include "qemu/main-loop.h" +#include "qemu/atomic.h" /***********************************************************/ /* bottom halves (can be seen as timers which expire ASAP) */ @@ -117,15 +118,21 @@ void qemu_bh_schedule_idle(QEMUBH *bh) void qemu_bh_schedule(QEMUBH *bh) { + AioContext *ctx; + if (bh->scheduled) return; + ctx = bh->ctx; bh->idle = 0; - /* Make sure that idle & any writes needed by the callback are done - * before the locations are read in the aio_bh_poll. + /* Make sure that: + * 1. idle & any writes needed by the callback are done before the + * locations are read in the aio_bh_poll. + * 2. ctx is loaded before scheduled is set and the callback has a chance + * to execute. */ - smp_wmb(); + smp_mb(); bh->scheduled = 1; - aio_notify(bh->ctx); + aio_notify(ctx); } @@ -241,9 +248,25 @@ ThreadPool *aio_get_thread_pool(AioContext *ctx) return ctx->thread_pool; } +void aio_set_dispatching(AioContext *ctx, bool dispatching) +{ + ctx->dispatching = dispatching; + if (!dispatching) { + /* Write ctx->dispatching before reading e.g. bh->scheduled. + * Optimization: this is only needed when we're entering the "unsafe" + * phase where other threads must call event_notifier_set. + */ + smp_mb(); + } +} + void aio_notify(AioContext *ctx) { - event_notifier_set(&ctx->notifier); + /* Write e.g. bh->scheduled before reading ctx->dispatching. */ + smp_mb(); + if (!ctx->dispatching) { + event_notifier_set(&ctx->notifier); + } } static void aio_timerlist_notify(void *opaque) |