bug in async select read

buganizer 1589219
channel is returning same values multiple times

R=r
OCL=23447
CL=23447

diff --git a/src/runtime/chan.c b/src/runtime/chan.c
index f6e245320fe443fdc9383480a929b60f09c96a4a..929d07f7ea3f071e3bc4fced3997415f18916b5e 100644 (file)
--- a/src/runtime/chan.c
+++ b/src/runtime/chan.c
@@ -5,6 +5,7 @@
 #include "runtime.h"
 
 static int32   debug   = 0;
+static int32   xxx     = 0;
 static Lock            chanlock;
 
 typedef        struct  Hchan   Hchan;
@@ -17,8 +18,9 @@ typedef       struct  Scase   Scase;
 struct SudoG
 {
        G*      g;              // g and selgen constitute
-       int16   offset;         // offset of case number
        int32   selgen;         // a weak pointer to g
+       int16   offset;         // offset of case number
+       int8    isfree;         // offset of case number
        SudoG*  link;
        byte    elem[8];        // synch data element (+ more)
 };
@@ -206,7 +208,6 @@ sendchan(Hchan *c, byte *ep, bool *pres)
        return;
 
 asynch:
-//prints("\nasend\n");
        while(c->qcount >= c->dataqsiz) {
                if(pres != nil) {
                        unlock(&chanlock);
@@ -229,10 +230,8 @@ asynch:
        sg = dequeue(&c->recvq, c);
        if(sg != nil) {
                gp = sg->g;
-               gp->param = sg;
                freesg(c, sg);
                unlock(&chanlock);
-//prints("wakeup\n");
                ready(gp);
        } else
                unlock(&chanlock);
@@ -312,7 +311,6 @@ asynch:
        sg = dequeue(&c->sendq, c);
        if(sg != nil) {
                gp = sg->g;
-               gp->param = sg;
                freesg(c, sg);
                unlock(&chanlock);
                ready(gp);
@@ -411,7 +409,7 @@ sys·newselect(int32 size, Select *sel)
        if(debug) {
                prints("newselect s=");
                sys·printpointer(sel);
-               prints("newselect size=");
+               prints(" size=");
                sys·printint(size);
                prints("\n");
        }
@@ -451,7 +449,7 @@ sys·selectsend(Select *sel, Hchan *c, ...)
        c->elemalg->copy(c->elemsize, cas->u.elem, ae);
 
        if(debug) {
-               prints("newselect s=");
+               prints("selectsend s=");
                sys·printpointer(sel);
                prints(" pc=");
                sys·printpointer(cas->pc);
@@ -495,7 +493,7 @@ sys·selectrecv(Select *sel, Hchan *c, ...)
        cas->u.elemp = *(byte**)((byte*)&sel + eo);
 
        if(debug) {
-               prints("newselect s=");
+               prints("selectrecv s=");
                sys·printpointer(sel);
                prints(" pc=");
                sys·printpointer(cas->pc);
@@ -510,7 +508,7 @@ sys·selectrecv(Select *sel, Hchan *c, ...)
 }
 
 
-// selectrecv(sel *byte) (selected bool);
+// selectdefaul(sel *byte) (selected bool);
 void
 sys·selectdefault(Select *sel, ...)
 {
@@ -534,7 +532,7 @@ sys·selectdefault(Select *sel, ...)
        cas->u.elemp = nil;
 
        if(debug) {
-               prints("newselect s=");
+               prints("selectdefault s=");
                sys·printpointer(sel);
                prints(" pc=");
                sys·printpointer(cas->pc);
@@ -546,7 +544,6 @@ sys·selectdefault(Select *sel, ...)
        }
 }
 
-uint32 xxx     = 0;
 
 // selectgo(sel *byte);
 void
@@ -589,6 +586,7 @@ sys·selectgo(Select *sel)
 
        lock(&chanlock);
 
+loop:
        // pass 1 - look for something already waiting
        dfl = nil;
        for(i=0; i<sel->ncase; i++) {
@@ -688,16 +686,25 @@ sys·selectgo(Select *sel)
                        o -= sel->ncase;
        }
 
+       g->param = nil;
        g->status = Gwaiting;
        unlock(&chanlock);
        sys·Gosched();
 
        lock(&chanlock);
        sg = g->param;
+       if(sg == nil)
+               goto loop;
+
        o = sg->offset;
        cas = sel->scase[o];
        c = cas->chan;
 
+       if(c->dataqsiz > 0) {
+//             prints("shouldnt happen\n");
+               goto loop;
+       }
+
        if(xxx) {
                prints("wait-return: sel=");
                sys·printpointer(sel);
@@ -712,12 +719,6 @@ sys·selectgo(Select *sel)
                prints("\n");
        }
 
-       if(c->dataqsiz > 0) {
-               if(cas->send)
-                       goto asyns;
-               goto asynr;
-       }
-
        if(!cas->send) {
                if(cas->u.elemp != nil)
                        c->elemalg->copy(c->elemsize, cas->u.elemp, sg->elem);
@@ -734,7 +735,6 @@ asynr:
        sg = dequeue(&c->sendq, c);
        if(sg != nil) {
                gp = sg->g;
-               gp->param = sg;
                freesg(c, sg);
                ready(gp);
        }
@@ -748,7 +748,6 @@ asyns:
        sg = dequeue(&c->recvq, c);
        if(sg != nil) {
                gp = sg->g;
-               gp->param = sg;
                freesg(c, sg);
                ready(gp);
        }
@@ -849,6 +848,7 @@ allocsg(Hchan *c)
        sg->selgen = g->selgen;
        sg->g = g;
        sg->offset = 0;
+       sg->isfree = 0;
 
        return sg;
 }
@@ -856,6 +856,9 @@ allocsg(Hchan *c)
 static void
 freesg(Hchan *c, SudoG *sg)
 {
+       if(sg->isfree)
+               throw("chan.freesg: already free");
+       sg->isfree = 1;
        sg->link = c->free;
        c->free = sg;
 }