diff options
Diffstat (limited to 'src/runtime/stack.go')
| -rw-r--r-- | src/runtime/stack.go | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/src/runtime/stack.go b/src/runtime/stack.go index 6e1f07bf73..52e54171cb 100644 --- a/src/runtime/stack.go +++ b/src/runtime/stack.go @@ -794,7 +794,16 @@ func syncadjustsudogs(gp *g, used uintptr, adjinfo *adjustinfo) uintptr { var lastc *hchan for sg := gp.waiting; sg != nil; sg = sg.waitlink { if sg.c != lastc { - lock(&sg.c.lock) + // There is a ranking cycle here between gscan bit and + // hchan locks. Normally, we only allow acquiring hchan + // locks and then getting a gscan bit. In this case, we + // already have the gscan bit. We allow acquiring hchan + // locks here as a special case, since a deadlock can't + // happen because the G involved must already be + // suspended. So, we get a special hchan lock rank here + // that is lower than gscan, but doesn't allow acquiring + // any other locks other than hchan. + lockWithRank(&sg.c.lock, lockRankHchanLeaf) } lastc = sg.c } |