SUNRPC: Fix a potential race in rpc_wake_up_task()
Use RCU to ensure that we can safely call rpc_finish_wakeup after we've
called __rpc_do_wake_up_task. If not, there is a theoretical race, in which
the rpc_task finishes executing, and gets freed first.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 883dd4a..29d8820 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -102,13 +102,19 @@
return p;
}
-void nfs_commit_free(struct nfs_write_data *p)
+void nfs_commit_rcu_free(struct rcu_head *head)
{
+ struct nfs_write_data *p = container_of(head, struct nfs_write_data, task.u.tk_rcu);
if (p && (p->pagevec != &p->page_array[0]))
kfree(p->pagevec);
mempool_free(p, nfs_commit_mempool);
}
+void nfs_commit_free(struct nfs_write_data *wdata)
+{
+ call_rcu_bh(&wdata->task.u.tk_rcu, nfs_commit_rcu_free);
+}
+
struct nfs_write_data *nfs_writedata_alloc(size_t len)
{
unsigned int pagecount = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
@@ -131,13 +137,19 @@
return p;
}
-static void nfs_writedata_free(struct nfs_write_data *p)
+static void nfs_writedata_rcu_free(struct rcu_head *head)
{
+ struct nfs_write_data *p = container_of(head, struct nfs_write_data, task.u.tk_rcu);
if (p && (p->pagevec != &p->page_array[0]))
kfree(p->pagevec);
mempool_free(p, nfs_wdata_mempool);
}
+static void nfs_writedata_free(struct nfs_write_data *wdata)
+{
+ call_rcu_bh(&wdata->task.u.tk_rcu, nfs_writedata_rcu_free);
+}
+
void nfs_writedata_release(void *wdata)
{
nfs_writedata_free(wdata);
@@ -258,7 +270,7 @@
io_error:
nfs_end_data_update(inode);
end_page_writeback(page);
- nfs_writedata_free(wdata);
+ nfs_writedata_release(wdata);
return written ? written : result;
}
@@ -1043,7 +1055,7 @@
while (!list_empty(&list)) {
data = list_entry(list.next, struct nfs_write_data, pages);
list_del(&data->pages);
- nfs_writedata_free(data);
+ nfs_writedata_release(data);
}
nfs_mark_request_dirty(req);
nfs_clear_page_writeback(req);