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| author | Stefan Hajnoczi <stefanha@redhat.com> | 2018-03-07 12:46:19 +0000 |
|---|---|---|
| committer | Stefan Hajnoczi <stefanha@redhat.com> | 2018-03-12 11:07:37 +0000 |
| commit | 7376eda7c2e0451e819e81bd05fabc56a9deb946 (patch) | |
| tree | c5a89490ebd3871f68331544ad39567ca4f0e832 /util | |
| parent | e4ae62b802cec437f877f2cadc4ef059cc0eca76 (diff) | |
| download | qemu-7376eda7c2e0451e819e81bd05fabc56a9deb946.zip qemu-7376eda7c2e0451e819e81bd05fabc56a9deb946.tar.gz qemu-7376eda7c2e0451e819e81bd05fabc56a9deb946.tar.bz2 | |
block: make BDRV_POLL_WHILE() re-entrancy safe
Nested BDRV_POLL_WHILE() calls can occur. Currently
assert(!wait_->wakeup) fails in AIO_WAIT_WHILE() when this happens.
This patch converts the bool wait_->need_kick flag to an unsigned
wait_->num_waiters counter.
Nesting works correctly because outer AIO_WAIT_WHILE() callers evaluate
the condition again after the inner caller completes (invoking the inner
caller counts as aio_poll() progress).
Reported-by: "fuweiwei (C)" <fuweiwei2@huawei.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20180307124619.6218-1-stefanha@redhat.com
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'util')
| -rw-r--r-- | util/aio-wait.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/util/aio-wait.c b/util/aio-wait.c index 975afdd..b8a8f86 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); } } |