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kernel: duppage checking

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cinap_lenrek 2012-02-16 11:38:50 +01:00
parent 739846b452
commit 083612b34e
2 changed files with 22 additions and 15 deletions
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19
sys/src/9/port/fault.c
View File

@ -140,14 +140,20 @@ fixfault(Segment *s, ulong addr, int read, int doputmmu)
lkp = *pg;
lock(lkp);
if(lkp->ref <= 0)
panic("fault: lkp->ref %d <= 0", lkp->ref);
if(lkp->image == &swapimage)
ref = lkp->ref + swapcount(lkp->daddr);
else
ref = lkp->ref;
if(ref > 1) {
unlock(lkp);
if(ref == 1 && lkp->image){
/* save a copy of the original for the image cache */
duppage(lkp);
ref = lkp->ref;
}
unlock(lkp);
if(ref > 1){
new = newpage(0, &s, addr);
if(s == 0)
return -1;
@ -155,13 +161,6 @@ fixfault(Segment *s, ulong addr, int read, int doputmmu)
copypage(lkp, *pg);
putpage(lkp);
}
else {
/* save a copy of the original for the image cache */
if(lkp->image)
duppage(lkp);
unlock(lkp);
}
mmuphys = PPN((*pg)->pa) | PTEWRITE | PTEVALID;
(*pg)->modref = PG_MOD|PG_REF;
break;

18
sys/src/9/port/page.c
View File

@ -275,6 +275,17 @@ duppage(Page *p) /* Always call with p locked */
retries = 0;
retry:
/* don't dup shared page */
if(p->ref != 1){
print("duppage: p->ref %d != 1\n", p->ref);
return 0;
}
/* don't dup pages with no image */
if(p->image == nil || p->image->notext){
print("duppage: noimage\n");
return 0;
}
if(retries++ > dupretries){
print("duppage %d, up %p\n", retries, up);
@ -284,11 +295,6 @@ retry:
uncachepage(p);
return 1;
}
/* don't dup pages with no image */
if(p->ref == 0 || p->image == nil || p->image->notext)
return 0;
/*
* normal lock ordering is to call
@ -337,6 +343,8 @@ retry:
* once they finally lock(np).
*/
lock(np);
if(np->ref != 0) /* should never happen */
panic("duppage: np->ref %d != 0\n", np->ref);
unlock(&palloc);
/* Cache the new version */