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| author | Peter Maydell <peter.maydell@linaro.org> | 2018-03-13 10:49:02 +0000 |
|---|---|---|
| committer | Peter Maydell <peter.maydell@linaro.org> | 2018-03-13 10:49:02 +0000 |
| commit | 834eddf22ec762839b724538c7be1d1d3b2d9d3b (patch) | |
| tree | 0b0a5cc0ede08b8df8706a074579687ebcab5559 | |
| parent | 73988d529e2edfc0c83cb73c07f818fdfebd633c (diff) | |
| parent | 7376eda7c2e0451e819e81bd05fabc56a9deb946 (diff) | |
Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging
# gpg: Signature made Mon 12 Mar 2018 16:01:16 GMT
# gpg: using RSA key 9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>"
# gpg: aka "Stefan Hajnoczi <stefanha@gmail.com>"
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35 775A 9CA4 ABB3 81AB 73C8
* remotes/stefanha/tags/block-pull-request:
block: make BDRV_POLL_WHILE() re-entrancy safe
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
| -rw-r--r-- | include/block/aio-wait.h | 61 | ||||
| -rw-r--r-- | util/aio-wait.c | 2 |
2 files changed, 31 insertions, 32 deletions
diff --git a/include/block/aio-wait.h b/include/block/aio-wait.h index f7a3972200..8c90a2e66e 100644 --- a/include/block/aio-wait.h +++ b/include/block/aio-wait.h @@ -50,8 +50,8 @@ * } */ typedef struct { - /* Is the main loop waiting for a kick? Accessed with atomic ops. */ - bool need_kick; + /* Number of waiting AIO_WAIT_WHILE() callers. Accessed with atomic ops. */ + unsigned num_waiters; } AioWait; /** @@ -71,35 +71,34 @@ typedef struct { * wait on conditions between two IOThreads since that could lead to deadlock, * go via the main loop instead. */ -#define AIO_WAIT_WHILE(wait, ctx, cond) ({ \ - bool waited_ = false; \ - bool busy_ = true; \ - AioWait *wait_ = (wait); \ - AioContext *ctx_ = (ctx); \ - if (in_aio_context_home_thread(ctx_)) { \ - while ((cond) || busy_) { \ - busy_ = aio_poll(ctx_, (cond)); \ - waited_ |= !!(cond) | busy_; \ - } \ - } else { \ - assert(qemu_get_current_aio_context() == \ - qemu_get_aio_context()); \ - assert(!wait_->need_kick); \ - /* Set wait_->need_kick before evaluating cond. */ \ - atomic_mb_set(&wait_->need_kick, true); \ - while (busy_) { \ - if ((cond)) { \ - waited_ = busy_ = true; \ - aio_context_release(ctx_); \ - aio_poll(qemu_get_aio_context(), true); \ - aio_context_acquire(ctx_); \ - } else { \ - busy_ = aio_poll(ctx_, false); \ - waited_ |= busy_; \ - } \ - } \ - atomic_set(&wait_->need_kick, false); \ - } \ +#define AIO_WAIT_WHILE(wait, ctx, cond) ({ \ + bool waited_ = false; \ + bool busy_ = true; \ + AioWait *wait_ = (wait); \ + AioContext *ctx_ = (ctx); \ + if (in_aio_context_home_thread(ctx_)) { \ + while ((cond) || busy_) { \ + busy_ = aio_poll(ctx_, (cond)); \ + waited_ |= !!(cond) | busy_; \ + } \ + } else { \ + assert(qemu_get_current_aio_context() == \ + qemu_get_aio_context()); \ + /* Increment wait_->num_waiters before evaluating cond. */ \ + atomic_inc(&wait_->num_waiters); \ + while (busy_) { \ + if ((cond)) { \ + waited_ = busy_ = true; \ + aio_context_release(ctx_); \ + aio_poll(qemu_get_aio_context(), true); \ + aio_context_acquire(ctx_); \ + } else { \ + busy_ = aio_poll(ctx_, false); \ + waited_ |= busy_; \ + } \ + } \ + atomic_dec(&wait_->num_waiters); \ + } \ waited_; }) /** diff --git a/util/aio-wait.c b/util/aio-wait.c index 975afddf4c..b8a8f86dba 100644 --- a/util/aio-wait.c +++ b/util/aio-wait.c @@ -34,7 +34,7 @@ static void dummy_bh_cb(void *opaque) void aio_wait_kick(AioWait *wait) { /* The barrier (or an atomic op) is in the caller. */ - if (atomic_read(&wait->need_kick)) { + if (atomic_read(&wait->num_waiters)) { aio_bh_schedule_oneshot(qemu_get_aio_context(), dummy_bh_cb, NULL); } } |