SUNRPC: Don't hold the transport lock across socket copy operations
Instead add a mechanism to ensure that the request doesn't disappear
from underneath us while copying from the socket. We do this by
preventing xprt_release() from freeing the XDR buffers until the
flag RPC_TASK_MSG_RECV has been cleared from the request.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index 4654a99..3eb9ec1 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -844,6 +844,48 @@
}
EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
+/**
+ * xprt_pin_rqst - Pin a request on the transport receive list
+ * @req: Request to pin
+ *
+ * Caller must ensure this is atomic with the call to xprt_lookup_rqst()
+ * so should be holding the xprt transport lock.
+ */
+void xprt_pin_rqst(struct rpc_rqst *req)
+{
+ set_bit(RPC_TASK_MSG_RECV, &req->rq_task->tk_runstate);
+}
+
+/**
+ * xprt_unpin_rqst - Unpin a request on the transport receive list
+ * @req: Request to pin
+ *
+ * Caller should be holding the xprt transport lock.
+ */
+void xprt_unpin_rqst(struct rpc_rqst *req)
+{
+ struct rpc_task *task = req->rq_task;
+
+ clear_bit(RPC_TASK_MSG_RECV, &task->tk_runstate);
+ if (test_bit(RPC_TASK_MSG_RECV_WAIT, &task->tk_runstate))
+ wake_up_bit(&task->tk_runstate, RPC_TASK_MSG_RECV);
+}
+
+static void xprt_wait_on_pinned_rqst(struct rpc_rqst *req)
+__must_hold(&req->rq_xprt->transport_lock)
+{
+ struct rpc_task *task = req->rq_task;
+
+ if (task && test_bit(RPC_TASK_MSG_RECV, &task->tk_runstate)) {
+ spin_unlock_bh(&req->rq_xprt->transport_lock);
+ set_bit(RPC_TASK_MSG_RECV_WAIT, &task->tk_runstate);
+ wait_on_bit(&task->tk_runstate, RPC_TASK_MSG_RECV,
+ TASK_UNINTERRUPTIBLE);
+ clear_bit(RPC_TASK_MSG_RECV_WAIT, &task->tk_runstate);
+ spin_lock_bh(&req->rq_xprt->transport_lock);
+ }
+}
+
static void xprt_update_rtt(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
@@ -1295,6 +1337,7 @@
list_del(&req->rq_list);
xprt->last_used = jiffies;
xprt_schedule_autodisconnect(xprt);
+ xprt_wait_on_pinned_rqst(req);
spin_unlock_bh(&xprt->transport_lock);
if (req->rq_buffer)
xprt->ops->buf_free(task);