Fix SIGCHLD race in signal handler setup#5210
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lifubang merged 1 commit intoopencontainers:mainfrom Apr 2, 2026
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kolyshkin
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signals.go
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| } | ||
| handler := make(chan *signalHandler) | ||
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| // ensure that we have a large buffer size so that we do not miss any |
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a very minor nit:
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| // ensure that we have a large buffer size so that we do not miss any | |
| // Ensure that we have a large buffer size so that we do not miss any |
kolyshkin
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Apr 1, 2026
signals.go
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| // setup. | ||
| // But `SIGCHLD` is very important, so we need to handle it immediately. |
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| // setup. | |
| // But `SIGCHLD` is very important, so we need to handle it immediately. | |
| - // setup. | |
| + // setup, except for SIGCHLD which is very important (see #5208). |
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I want to include this into 1.5.0rc2, @opencontainers/runc-maintainers ptal |
AkihiroSuda
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Apr 1, 2026
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@lifubang feel free to merge as is or modify the comments, either way is fine with me. Once merged, please open an 1.5 backport, I want to release rc2 asap |
When signal installation was moved to a goroutine for performance, containers that exited quickly could complete before SIGCHLD was registered, causing runc to hang waiting for the signal. This fix ensures SIGCHLD is registered immediately in the main thread before other signals are handled in the goroutine, maintaining performance while guaranteeing no missed SIGCHLD notifications for fast-exiting containers. Reported-by: Ayato Tokubi <atokubi@redhat.com> Signed-off-by: lifubang <lifubang@acmcoder.com>
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This is an alternative to #5206.
Fix: #5208
When signal installation was moved to a goroutine for performance(#4654), containers that exited quickly could complete before SIGCHLD was registered, causing runc to hang waiting for the signal.
This fix ensures SIGCHLD is registered immediately in the main thread before other signals are handled in the goroutine, maintaining performance while guaranteeing no missed SIGCHLD notifications for fast-exiting containers.
Reported-by: Ayato Tokubi atokubi@redhat.com