diff options
| -rw-r--r-- | kalloc.c | 41 |
1 files changed, 17 insertions, 24 deletions
@@ -47,9 +47,9 @@ kinit(void) void kfree(char *v, int len) { - struct run **rr, *p, *pend; + struct run *r, *rend, **rp, *p, *pend; - if(len % PAGE) + if(len <= 0 || len % PAGE) panic("kfree"); // Fill with junk to catch dangling refs. @@ -58,36 +58,29 @@ kfree(char *v, int len) acquire(&kalloc_lock); p = (struct run*)v; pend = (struct run*)(v + len); - rr = &freelist; - while(*rr){ - struct run *rend = (struct run*) ((char*)(*rr) + (*rr)->len); - if(p >= *rr && p < rend) + for(rp=&freelist; (r=*rp) != 0 && r <= pend; rp=&r->next){ + rend = (struct run*)((char*)r + r->len); + if(r <= p && p < rend) panic("freeing free page"); - if(pend == *rr){ - p->len = len + (*rr)->len; - p->next = (*rr)->next; - *rr = p; - goto out; - } - if(pend < *rr){ - p->len = len; - p->next = *rr; - *rr = p; + if(pend == r){ // p next to r: replace r with p + p->len = len + r->len; + p->next = r->next; + *rp = p; goto out; } - if(p == rend){ - (*rr)->len += len; - if((*rr)->next && (*rr)->next == pend){ - (*rr)->len += (*rr)->next->len; - (*rr)->next = (*rr)->next->next; + if(rend == p){ // r next to p: replace p with r + r->len += len; + if(r->next && r->next == pend){ // r now next to r->next? + r->len += r->next->len; + r->next = r->next->next; } goto out; } - rr = &((*rr)->next); } + // Insert p before r in list. p->len = len; - p->next = 0; - *rr = p; + p->next = r; + *rp = p; out: release(&kalloc_lock); |