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TS-4487: check the change of lock after return from wbe callback #754

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Merged
shinrich merged 1 commit into from
Jul 3, 2016
Merged

TS-4487: check the change of lock after return from wbe callback #754

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23 changes: 14 additions & 9 deletions iocore/net/UnixNetVConnection.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -556,13 +556,17 @@ write_to_net_io(NetHandler *nh, UnixNetVConnection *vc, EThread *thread)
if (s->vio.ntodo() <= 0) {
write_signal_done(VC_EVENT_WRITE_COMPLETE, nh, vc);
return;
} else if (signalled && (wbe_event != vc->write_buffer_empty_event)) {
}
int e = 0;
if (!signalled) {
e = VC_EVENT_WRITE_READY;
} else if (wbe_event != vc->write_buffer_empty_event) {
// @a signalled means we won't send an event, and the event values differing means we
// had a write buffer trap and cleared it, so we need to send it now.
if (write_signal_and_update(wbe_event, vc) != EVENT_CONT)
return;
} else if (!signalled) {
if (write_signal_and_update(VC_EVENT_WRITE_READY, vc) != EVENT_CONT) {
e = wbe_event;
}
if (e) {
if (write_signal_and_update(e, vc) != EVENT_CONT) {
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@shinrich shinrich Jun 29, 2016

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Took me a bit to understand the point of this tidying up. But looking back at the bug description, this rearrangement stops the early return which would miss the lock change detection. So that makes sense.

return;
}

Expand All @@ -573,17 +577,18 @@ write_to_net_io(NetHandler *nh, UnixNetVConnection *vc, EThread *thread)
}
}

if (!buf.reader()->read_avail()) {
if ((needs & EVENTIO_READ) == EVENTIO_READ) {
read_reschedule(nh, vc);
}

if (!(buf.reader()->is_read_avail_more_than(0))) {
write_disable(nh, vc);
return;
}

if ((needs & EVENTIO_WRITE) == EVENTIO_WRITE) {
write_reschedule(nh, vc);
}
if ((needs & EVENTIO_READ) == EVENTIO_READ) {
read_reschedule(nh, vc);
}
return;
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@shinrich shinrich Jun 29, 2016

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Moving up the read enable check looks good.

}
}
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