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| author | Max Reitz <mreitz@redhat.com> | 2019-07-22 15:30:53 +0200 |
|---|---|---|
| committer | Max Reitz <mreitz@redhat.com> | 2019-07-22 18:41:35 +0200 |
| commit | 65181d63817b33b10ecb1c418eb96c99e7cf8842 (patch) | |
| tree | 8c5619e74ceeab10b9dc6826dba86c622f4b29fd /include | |
| parent | 258867d1dc32c300690cc32bfcf3e648ae12c4c9 (diff) | |
| download | qemu-65181d63817b33b10ecb1c418eb96c99e7cf8842.zip | |
block: Dec. drained_end_counter before bdrv_wakeup
Decrementing drained_end_counter after bdrv_dec_in_flight() (which in
turn invokes bdrv_wakeup() and thus aio_wait_kick()) is not very clever.
We should decrement it beforehand, so that any waiting aio_poll() that
is woken by bdrv_dec_in_flight() sees the decremented
drained_end_counter.
Because the time window between decrementing drained_end_counter and
aio_wait_kick() is very small, I cannot supply a reliable regression
test. However, running e.g. the /bdrv-drain/blockjob/iothread/drain_all
test in test-bdrv-drain has a small chance of hanging without this
patch (about 1/200 or so; it gets to nearly 100 % if you add e.g. an
fputc(' ', stderr); after the bdrv_dec_in_flight()).
Fixes: e037c09c78520cbdb6da7cfc6ad0256d5870b814
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190722133054.21781-2-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Diffstat (limited to 'include')
0 files changed, 0 insertions, 0 deletions