diff options
Diffstat (limited to 'src/runtime/trace2runtime.go')
| -rw-r--r-- | src/runtime/trace2runtime.go | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/src/runtime/trace2runtime.go b/src/runtime/trace2runtime.go index a9c8d8a590..9638e4b924 100644 --- a/src/runtime/trace2runtime.go +++ b/src/runtime/trace2runtime.go @@ -192,7 +192,12 @@ func traceAcquireEnabled() traceLocker { // Prevent preemption. mp := acquirem() - // Acquire the trace seqlock. + // Acquire the trace seqlock. This prevents traceAdvance from moving forward + // until all Ms are observed to be outside of their seqlock critical section. + // + // Note: The seqlock is mutated here and also in traceCPUSample. If you update + // usage of the seqlock here, make sure to also look at what traceCPUSample is + // doing. seq := mp.trace.seqlock.Add(1) if debugTraceReentrancy && seq%2 != 1 { throw("bad use of trace.seqlock or tracer is reentrant") |