From a1674f3ee30bf46d22fcac115529ce830f8c9ac9 Mon Sep 17 00:00:00 2001 From: Ian Lance Taylor Date: Tue, 16 May 2023 16:03:38 -0700 Subject: runtime: publish netpoll info after incrementing fdseq I think there is a theoretical possibility of a mistake before this CL. pollCache.free would increment fdseq, but would not update atomicInfo. The epoll code could compare to fdseq before the increment, but suspend before calling setEventErr. The pollCache could get reallocated, and pollOpen could clear eventErr. Then the setEventErr could continue and set it again. Then pollOpen could call publishInfo. Avoid this rather remote possibility by calling publishInfo after incrementing fdseq. That ensures that delayed setEventErr will not modify the eventErr flag. Fixes #60133 Change-Id: I69e336535312544690821c9fd53f3023ff15b80c Reviewed-on: https://go-review.googlesource.com/c/go/+/495297 Run-TryBot: Ian Lance Taylor TryBot-Result: Gopher Robot Reviewed-by: Ian Lance Taylor Run-TryBot: Ian Lance Taylor Reviewed-by: Bryan Mills Auto-Submit: Ian Lance Taylor --- src/runtime/netpoll.go | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/src/runtime/netpoll.go b/src/runtime/netpoll.go index b1b3766e11..a2b0be2261 100644 --- a/src/runtime/netpoll.go +++ b/src/runtime/netpoll.go @@ -287,12 +287,20 @@ func poll_runtime_pollClose(pd *pollDesc) { } func (c *pollCache) free(pd *pollDesc) { + // pd can't be shared here, but lock anyhow because + // that's what publishInfo documents. + lock(&pd.lock) + // Increment the fdseq field, so that any currently // running netpoll calls will not mark pd as ready. fdseq := pd.fdseq.Load() fdseq = (fdseq + 1) & (1<