diff options
Diffstat (limited to 'src/runtime/proc.go')
| -rw-r--r-- | src/runtime/proc.go | 48 |
1 files changed, 28 insertions, 20 deletions
diff --git a/src/runtime/proc.go b/src/runtime/proc.go index b997a467ba..cae15bc8e2 100644 --- a/src/runtime/proc.go +++ b/src/runtime/proc.go @@ -1508,19 +1508,18 @@ func mexit(osStack bool) { } throw("m not found in allm") found: - if !osStack { - // Delay reaping m until it's done with the stack. - // - // If this is using an OS stack, the OS will free it - // so there's no need for reaping. - atomic.Store(&m.freeWait, 1) - // Put m on the free list, though it will not be reaped until - // freeWait is 0. Note that the free list must not be linked - // through alllink because some functions walk allm without - // locking, so may be using alllink. - m.freelink = sched.freem - sched.freem = m - } + // Delay reaping m until it's done with the stack. + // + // Put mp on the free list, though it will not be reaped while freeWait + // is freeMWait. mp is no longer reachable via allm, so even if it is + // on an OS stack, we must keep a reference to mp alive so that the GC + // doesn't free mp while we are still using it. + // + // Note that the free list must not be linked through alllink because + // some functions walk allm without locking, so may be using alllink. + m.freeWait.Store(freeMWait) + m.freelink = sched.freem + sched.freem = m unlock(&sched.lock) atomic.Xadd64(&ncgocall, int64(m.ncgocall)) @@ -1550,6 +1549,9 @@ found: mdestroy(m) if osStack { + // No more uses of mp, so it is safe to drop the reference. + m.freeWait.Store(freeMRef) + // Return from mstart and let the system thread // library free the g0 stack and terminate the thread. return @@ -1721,19 +1723,25 @@ func allocm(_p_ *p, fn func(), id int64) *m { lock(&sched.lock) var newList *m for freem := sched.freem; freem != nil; { - if freem.freeWait != 0 { + wait := freem.freeWait.Load() + if wait == freeMWait { next := freem.freelink freem.freelink = newList newList = freem freem = next continue } - // stackfree must be on the system stack, but allocm is - // reachable off the system stack transitively from - // startm. - systemstack(func() { - stackfree(freem.g0.stack) - }) + // Free the stack if needed. For freeMRef, there is + // nothing to do except drop freem from the sched.freem + // list. + if wait == freeMStack { + // stackfree must be on the system stack, but allocm is + // reachable off the system stack transitively from + // startm. + systemstack(func() { + stackfree(freem.g0.stack) + }) + } freem = freem.freelink } sched.freem = newList |