console_linux: Fix race: lock Cond before Signal. #27
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It looks, like your travis install/config has some problems. |
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Thanks, looking into the travis issue |
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@gerasiov could you rebase this on master? We merge a travis fix for the failing CI. |
Possible race: Thread1: Thread2: line 178: Read() -> EAGAIN ... <reschedule> line 110: EpollWait() ... line 124: signalRead() ... ... line 191: Wait() ... line 110: EpollWait() Thread2 (epoll) sends signalRead() (via sync.Cond) but Thread1 is not waiting yet. Then it starts to wait, but no more signals will arrive (because Thread2 is sleeping in EpollWait() on edge-triggered epoll. To prevent this race one should held Lock when sending signalRead(). The same situation goes with Write loop. Bug was reported to docker: docker/for-linux#353 Signed-off-by: Alexander Gerasiov <gerasiov@yandex-team.ru>
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LGTM |
mikebrow
reviewed
Jul 5, 2018
| ec.readc.Signal() | ||
| ec.readc.L.Unlock() |
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nit.. maybe use defer for the Unlock() calls to mirror existing code pattern.
This was referenced Jul 6, 2018
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Is there a way to track when this would make it into a Docker release? |
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@djmitche it looks like 18.06 has the fix: moby/moby#35865 (comment) |
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Signed-off-by: Petros Angelatos <petrosagg@gmail.com> Connects-To: moby/moby#35865 Connects-To: containerd/console#27
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relevant changes: - containerd/console#27 console_linux: Fix race: lock Cond before Signal Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
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relevant changes: - containerd/console#27 console_linux: Fix race: lock Cond before Signal Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
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relevant changes: - containerd/console#27 console_linux: Fix race: lock Cond before Signal Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
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relevant changes: - containerd/console#27 console_linux: Fix race: lock Cond before Signal Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
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relevant changes: - containerd/console#27 console_linux: Fix race: lock Cond before Signal Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
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relevant changes: - containerd/console#27 console_linux: Fix race: lock Cond before Signal Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
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relevant changes: - containerd/console#27 console_linux: Fix race: lock Cond before Signal Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
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relevant changes: - containerd/console#27 console_linux: Fix race: lock Cond before Signal Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
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relevant changes: - containerd/console#27 console_linux: Fix race: lock Cond before Signal Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
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relevant changes: - containerd/console#27 console_linux: Fix race: lock Cond before Signal Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
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relevant changes: - containerd/console#27 console_linux: Fix race: lock Cond before Signal Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
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Possible race:
Thread2 (epoll) sends signalRead() (via sync.Cond) but Thread1 is not waiting
yet. Then is start to wait, but no more signals will arrive (because Thread2
is sleeping in EpollWait() on edge-triggered epoll.
To prevent this race one should held Lock when sending signalRead().
The same situation goes with Write loop.
Bug was reported to docker: docker/for-linux#353
Signed-off-by: Alexander Gerasiov gerasiov@yandex-team.ru