Skip to content

X
xv6-public
提交 c0436a69 创建 作者: Nickolai Zeldovich's avatar Nickolai Zeldovich
浏览文件
操作

lock-free linked lists are susceptible to ABA races,

which actually show up on real hardware.. hmm.
上级 020f4b22
隐藏空白字符变更
内嵌 并排
正在显示 包含 14 行增加 和 7 行删除
kernel/exec.cc
浏览文件 @ c0436a69
...@@ -84,7 +84,6 @@ static void dostack(uptr a0, u64 a1) ...@@ -84,7 +84,6 @@ static void dostack(uptr a0, u64 a1)
goto bad; goto bad;
if(args->vmap->insert(vmn, USERTOP-(USTACKPAGES*PGSIZE), 1) < 0) if(args->vmap->insert(vmn, USERTOP-(USTACKPAGES*PGSIZE), 1) < 0)
goto bad; goto bad;
vmn = 0;
// Push argument strings, prepare rest of stack in ustack. // Push argument strings, prepare rest of stack in ustack.
sp = USERTOP; sp = USERTOP;
...@@ -135,7 +134,6 @@ static void doheap(uptr a0, u64 a1) ...@@ -135,7 +134,6 @@ static void doheap(uptr a0, u64 a1)
goto bad; goto bad;
if(args->vmap->insert(vmn, BRK, 1) < 0) if(args->vmap->insert(vmn, BRK, 1) < 0)
goto bad; goto bad;
vmn = 0;
prof_end(doheap_prof); prof_end(doheap_prof);
return; return;
...@@ -149,7 +147,6 @@ exec(char *path, char **argv) ...@@ -149,7 +147,6 @@ exec(char *path, char **argv)
{ {
struct inode *ip = NULL; struct inode *ip = NULL;
struct vmap *vmp = NULL; struct vmap *vmp = NULL;
struct vmnode *vmn = NULL;
struct elfhdr elf; struct elfhdr elf;
struct proghdr ph; struct proghdr ph;
u64 off; u64 off;
...@@ -227,8 +224,6 @@ exec(char *path, char **argv) ...@@ -227,8 +224,6 @@ exec(char *path, char **argv)
cprintf("exec failed\n"); cprintf("exec failed\n");
if(vmp) if(vmp)
vmp->decref(); vmp->decref();
if(vmn)
delete vmn;
gc_end_epoch(); gc_end_epoch();
return 0; return 0;
......
kernel/gc.cc
浏览文件 @ c0436a69
...@@ -58,6 +58,7 @@ gc_free_tofreelist(atomic<rcu_freed*> *head, u64 epoch) ...@@ -58,6 +58,7 @@ gc_free_tofreelist(atomic<rcu_freed*> *head, u64 epoch)
for (; r; r = nr) { for (; r; r = nr) {
if (r->_rcu_epoch > epoch) { if (r->_rcu_epoch > epoch) {
cprintf("gc_free_tofreelist: r->epoch %ld > epoch %ld\n", r->_rcu_epoch, epoch); cprintf("gc_free_tofreelist: r->epoch %ld > epoch %ld\n", r->_rcu_epoch, epoch);
cprintf("gc_free_tofreelist: name %s\n", r->_rcu_type);
assert(0); assert(0);
} }
nr = r->_rcu_next; nr = r->_rcu_next;
......
kernel/kalloc.cc
浏览文件 @ c0436a69
...@@ -170,9 +170,13 @@ kalloc_pool(struct kmem *km) ...@@ -170,9 +170,13 @@ kalloc_pool(struct kmem *km)
m = &km[cn]; m = &km[cn];
r = m->freelist; r = m->freelist;
while (r && !cmpxch_update(&m->freelist, &r, r->next)) run *nxt = r->next;
while (r && !cmpxch_update(&m->freelist, &r, nxt))
; /* spin */ ; /* spin */
if (r && r->next != nxt)
panic("kalloc_pool: aba race %p %p %p\n", r, r->next, nxt);
if (r) { if (r) {
m->nfree--; m->nfree--;
break; break;
......
kernel/kmalloc.cc
浏览文件 @ c0436a69
...@@ -88,11 +88,18 @@ kmalloc(u64 nbytes) ...@@ -88,11 +88,18 @@ kmalloc(u64 nbytes)
return 0; return 0;
} }
} else { } else {
if (cmpxch(&freelists[c].buckets[b], h, h->next)) header *nxt = h->next;
if (cmpxch(&freelists[c].buckets[b], h, nxt)) {
if (h->next != nxt)
panic("kmalloc: aba race");
break; break;
}
} }
} }
if (ALLOC_MEMSET)
memset(h, 4, (1<<b));
mtlabel(mtrace_label_heap, (void*) h, nbytes, "kmalloc'ed", sizeof("kmalloc'ed")); mtlabel(mtrace_label_heap, (void*) h, nbytes, "kmalloc'ed", sizeof("kmalloc'ed"));
return h; return h;
} }
......
您添加了 0 人 到此讨论。请谨慎行事。
请先完成此评论的编辑！
请 注册 或者 后发表评论