diff options
Diffstat (limited to 'src/pkg/runtime/stack.c')
| -rw-r--r-- | src/pkg/runtime/stack.c | 56 |
1 files changed, 39 insertions, 17 deletions
diff --git a/src/pkg/runtime/stack.c b/src/pkg/runtime/stack.c index 61205bd478..78d1e149e7 100644 --- a/src/pkg/runtime/stack.c +++ b/src/pkg/runtime/stack.c @@ -337,15 +337,20 @@ runtime·oldstack(void) top->gobuf.pc, top->gobuf.sp, top->gobuf.lr, (uintptr)g->m->cret, (uintptr)argsize); } - // gp->status is usually Grunning, but it could be Gsyscall if a stack overflow - // happens during a function call inside entersyscall. - oldstatus = gp->status; - gp->sched = top->gobuf; gp->sched.ret = g->m->cret; g->m->cret = 0; // drop reference - gp->status = Gwaiting; - gp->waitreason = runtime·gostringnocopy((byte*)"stack unsplit"); + // gp->status is usually Grunning, but it could be Gsyscall if a stack overflow + // happens during a function call inside entersyscall. + + oldstatus = runtime·readgstatus(gp); + oldstatus &= ~Gscan; + if(oldstatus != Grunning && oldstatus != Gsyscall) { + runtime·printf("runtime: oldstack status=%d\n", oldstatus); + runtime·throw("oldstack"); + } + runtime·casgstatus(gp, oldstatus, Gcopystack); + gp->waitreason = runtime·gostringnocopy((byte*)"stack unsplit"); if(argsize > 0) { sp -= argsize; @@ -363,8 +368,7 @@ runtime·oldstack(void) gp->stackguard0 = gp->stackguard; gp->panicwrap = top->panicwrap; runtime·stackfree(gp, old, top); - - gp->status = oldstatus; + runtime·casgstatus(gp, Gcopystack, oldstatus); // oldstatus is Grunning or Gsyscall runtime·gogo(&gp->sched); } @@ -768,6 +772,7 @@ copystack(G *gp, uintptr nframes, uintptr newsize) uintptr oldsize, used; AdjustInfo adjinfo; Stktop *oldtop, *newtop; + uint32 oldstatus; if(gp->syscallstack != 0) runtime·throw("can't handle stack copy in syscall yet"); @@ -801,7 +806,12 @@ copystack(G *gp, uintptr nframes, uintptr newsize) // copy the stack (including Stktop) to the new location runtime·memmove(newbase - used, oldbase - used, used); - + oldstatus = runtime·readgstatus(gp); + oldstatus &= ~Gscan; + if (oldstatus == Gwaiting || oldstatus == Grunnable) + runtime·casgstatus(gp, oldstatus, Gcopystack); // oldstatus is Gwaiting or Grunnable + else + runtime·throw("copystack: bad status, not Gwaiting or Grunnable"); // Swap out old stack for new one gp->stackbase = (uintptr)newtop; gp->stackguard = (uintptr)newstk + StackGuard; @@ -810,6 +820,8 @@ copystack(G *gp, uintptr nframes, uintptr newsize) gp->stack0 = (uintptr)newstk; gp->sched.sp = (uintptr)(newbase - used); + runtime·casgstatus(gp, Gcopystack, oldstatus); // oldstatus is Gwaiting or Grunnable + // free old stack runtime·stackfree(gp, oldstk, oldtop); } @@ -831,6 +843,9 @@ runtime·round2(int32 x) // m->moreframesize bytes, copy m->moreargsize bytes to the new frame, // and then act as though runtime·lessstack called the function at // m->morepc. +// +// g->atomicstatus will be Grunning, Gsyscall or Gscanrunning, Gscansyscall upon entry. +// If the GC is trying to stop this g then it will set preemptscan to true. void runtime·newstack(void) { @@ -853,11 +868,13 @@ runtime·newstack(void) runtime·throw("runtime: wrong goroutine in newstack"); } + // The goroutine must be executing in order to call newstack, so the possible states are + // Grunning and Gsyscall (and, due to GC, also Gscanrunning and Gscansyscall). + // gp->status is usually Grunning, but it could be Gsyscall if a stack overflow // happens during a function call inside entersyscall. gp = g->m->curg; - oldstatus = gp->status; - + oldstatus = runtime·readgstatus(gp) & ~Gscan; framesize = g->m->moreframesize; argsize = g->m->moreargsize; moreargp = g->m->moreargp; @@ -866,7 +883,8 @@ runtime·newstack(void) g->m->morebuf.pc = (uintptr)nil; g->m->morebuf.lr = (uintptr)nil; g->m->morebuf.sp = (uintptr)nil; - gp->status = Gwaiting; + + runtime·casgstatus(gp, oldstatus, Gwaiting); // oldstatus is not in a Gscan status gp->waitreason = runtime·gostringnocopy((byte*)"stack growth"); newstackcall = framesize==1; if(newstackcall) @@ -892,6 +910,7 @@ runtime·newstack(void) gp->sched.pc, gp->sched.sp, gp->sched.lr, gp->sched.ctxt); } if(sp < gp->stackguard - StackGuard) { + runtime·printf("runtime: gp=%p, gp->status=%d, oldstatus=%d\n ", (void*)gp, runtime·readgstatus(gp), oldstatus); runtime·printf("runtime: split stack overflow: %p < %p\n", sp, gp->stackguard - StackGuard); runtime·throw("runtime: split stack overflow"); } @@ -908,17 +927,18 @@ runtime·newstack(void) runtime·throw("runtime: g is running but p is not"); if(oldstatus == Gsyscall && g->m->locks == 0) runtime·throw("runtime: stack growth during syscall"); + // Be conservative about where we preempt. // We are interested in preempting user Go code, not runtime code. if(oldstatus != Grunning || g->m->locks || g->m->mallocing || g->m->gcing || g->m->p->status != Prunning) { // Let the goroutine keep running for now. // gp->preempt is set, so it will be preempted next time. gp->stackguard0 = gp->stackguard; - gp->status = oldstatus; + runtime·casgstatus(gp, Gwaiting, oldstatus); // oldstatus is Gsyscall or Grunning runtime·gogo(&gp->sched); // never return } // Act like goroutine called runtime.Gosched. - gp->status = oldstatus; + runtime·casgstatus(gp, Gwaiting, oldstatus); // oldstatus is Gsyscall or Grunning runtime·gosched_m(gp); // never return } @@ -933,6 +953,8 @@ runtime·newstack(void) oldbase = (byte*)gp->stackbase + sizeof(Stktop); oldsize = oldbase - oldstk; newsize = oldsize * 2; + // Note that the concurrent GC might be scanning the stack as we try to replace it. + // copystack takes care of the appropriate coordination with the stack scanner. copystack(gp, nframes, newsize); if(StackDebug >= 1) runtime·printf("stack grow done\n"); @@ -940,7 +962,7 @@ runtime·newstack(void) runtime·printf("runtime: goroutine stack exceeds %D-byte limit\n", (uint64)runtime·maxstacksize); runtime·throw("stack overflow"); } - gp->status = oldstatus; + runtime·casgstatus(gp, Gwaiting, oldstatus); // oldstatus is Gsyscall or Grunning runtime·gogo(&gp->sched); } // TODO: if stack is uncopyable because we're in C code, patch return value at @@ -1017,7 +1039,7 @@ runtime·newstack(void) runtime·gostartcall(&label, (void(*)(void))gp->sched.pc, gp->sched.ctxt); gp->sched.ctxt = nil; } - gp->status = oldstatus; + runtime·casgstatus(gp, Gwaiting, oldstatus); // oldstatus is Grunning or Gsyscall runtime·gogo(&label); *(int32*)345 = 123; // never return @@ -1055,7 +1077,7 @@ runtime·shrinkstack(G *gp) if(!runtime·copystack) return; - if(gp->status == Gdead) + if(runtime·readgstatus(gp) == Gdead) return; if(gp->stackbase == 0) runtime·throw("stackbase == 0"); |