diff options
Diffstat (limited to 'src/runtime/stack.go')
| -rw-r--r-- | src/runtime/stack.go | 30 |
1 files changed, 11 insertions, 19 deletions
diff --git a/src/runtime/stack.go b/src/runtime/stack.go index 2c2a88e6e1..e47f12a8dc 100644 --- a/src/runtime/stack.go +++ b/src/runtime/stack.go @@ -786,10 +786,6 @@ func syncadjustsudogs(gp *g, used uintptr, adjinfo *adjustinfo) uintptr { } // Lock channels to prevent concurrent send/receive. - // It's important that we *only* do this for async - // copystack; otherwise, gp may be in the middle of - // putting itself on wait queues and this would - // self-deadlock. var lastc *hchan for sg := gp.waiting; sg != nil; sg = sg.waitlink { if sg.c != lastc { @@ -826,12 +822,7 @@ func syncadjustsudogs(gp *g, used uintptr, adjinfo *adjustinfo) uintptr { // Copies gp's stack to a new stack of a different size. // Caller must have changed gp status to Gcopystack. -// -// If sync is true, this is a self-triggered stack growth and, in -// particular, no other G may be writing to gp's stack (e.g., via a -// channel operation). If sync is false, copystack protects against -// concurrent channel operations. -func copystack(gp *g, newsize uintptr, sync bool) { +func copystack(gp *g, newsize uintptr) { if gp.syscallsp != 0 { throw("stack growth not allowed in system call") } @@ -857,15 +848,16 @@ func copystack(gp *g, newsize uintptr, sync bool) { // Adjust sudogs, synchronizing with channel ops if necessary. ncopy := used - if sync { + if !gp.activeStackChans { adjustsudogs(gp, &adjinfo) } else { - // sudogs can point in to the stack. During concurrent - // shrinking, these areas may be written to. Find the - // highest such pointer so we can handle everything - // there and below carefully. (This shouldn't be far - // from the bottom of the stack, so there's little - // cost in handling everything below it carefully.) + // sudogs may be pointing in to the stack and gp has + // released channel locks, so other goroutines could + // be writing to gp's stack. Find the highest such + // pointer so we can handle everything there and below + // carefully. (This shouldn't be far from the bottom + // of the stack, so there's little cost in handling + // everything below it carefully.) adjinfo.sghi = findsghi(gp, old) // Synchronize with channel ops and copy the part of @@ -1040,7 +1032,7 @@ func newstack() { // The concurrent GC will not scan the stack while we are doing the copy since // the gp is in a Gcopystack status. - copystack(gp, newsize, true) + copystack(gp, newsize) if stackDebug >= 1 { print("stack grow done\n") } @@ -1120,7 +1112,7 @@ func shrinkstack(gp *g) { print("shrinking stack ", oldsize, "->", newsize, "\n") } - copystack(gp, newsize, false) + copystack(gp, newsize) } // freeStackSpans frees unused stack spans at the end of GC. |